diff --git a/lib/config.js b/lib/config.js
index e4da296de8f88..54462ee712b78 100644
--- a/lib/config.js
+++ b/lib/config.js
@@ -1,4 +1,3 @@
-const npm = require('./npm.js')
 const { defaults, types } = require('./utils/config.js')
 const usageUtil = require('./utils/usage.js')
 const output = require('./utils/output.js')
@@ -13,165 +12,156 @@ const { spawn } = require('child_process')
 const { EOL } = require('os')
 const ini = require('ini')
 
-const usage = usageUtil(
-  'config',
-  'npm config set <key>=<value> [<key>=<value> ...]' +
-  '\nnpm config get [<key> [<key> ...]]' +
-  '\nnpm config delete <key> [<key> ...]' +
-  '\nnpm config list [--json]' +
-  '\nnpm config edit' +
-  '\nnpm set <key>=<value> [<key>=<value> ...]' +
-  '\nnpm get [<key> [<key> ...]]'
-)
-
-const cmd = (args, cb) => config(args).then(() => cb()).catch(cb)
-
-const completion = async (opts) => {
-  const argv = opts.conf.argv.remain
-  if (argv[1] !== 'config')
-    argv.unshift('config')
-
-  if (argv.length === 2) {
-    const cmds = ['get', 'set', 'delete', 'ls', 'rm', 'edit']
-    if (opts.partialWord !== 'l')
-      cmds.push('list')
-
-    return cmds
+class Config {
+  constructor (npm) {
+    this.npm = npm
   }
 
-  const action = argv[2]
-  switch (action) {
-    case 'set':
-      // todo: complete with valid values, if possible.
-      if (argv.length > 3)
-        return []
-
-      // fallthrough
-      /* eslint no-fallthrough:0 */
-    case 'get':
-    case 'delete':
-    case 'rm':
-      return Object.keys(types)
-    case 'edit':
-    case 'list':
-    case 'ls':
-    default:
-      return []
+  get usage () {
+    return usageUtil(
+      'config',
+      'npm config set <key>=<value> [<key>=<value> ...]' +
+      '\nnpm config get [<key> [<key> ...]]' +
+      '\nnpm config delete <key> [<key> ...]' +
+      '\nnpm config list [--json]' +
+      '\nnpm config edit' +
+      '\nnpm set <key>=<value> [<key>=<value> ...]' +
+      '\nnpm get [<key> [<key> ...]]'
+    )
   }
-}
 
-const UsageError = () =>
-  Object.assign(new Error(usage), { code: 'EUSAGE' })
+  async completion (opts) {
+    const argv = opts.conf.argv.remain
+    if (argv[1] !== 'config')
+      argv.unshift('config')
 
-const config = async ([action, ...args]) => {
-  npm.log.disableProgress()
-  try {
+    if (argv.length === 2) {
+      const cmds = ['get', 'set', 'delete', 'ls', 'rm', 'edit']
+      if (opts.partialWord !== 'l')
+        cmds.push('list')
+
+      return cmds
+    }
+
+    const action = argv[2]
     switch (action) {
       case 'set':
-        await set(args)
-        break
+        // todo: complete with valid values, if possible.
+        if (argv.length > 3)
+          return []
+
+        // fallthrough
+        /* eslint no-fallthrough:0 */
       case 'get':
-        await get(args)
-        break
       case 'delete':
       case 'rm':
-      case 'del':
-        await del(args)
-        break
+        return Object.keys(types)
+      case 'edit':
       case 'list':
       case 'ls':
-        await (npm.flatOptions.json ? listJson() : list())
-        break
-      case 'edit':
-        await edit()
-        break
       default:
-        throw UsageError()
+        return []
     }
-  } finally {
-    npm.log.enableProgress()
   }
-}
 
-// take an array of `[key, value, k2=v2, k3, v3, ...]` and turn into
-// { key: value, k2: v2, k3: v3 }
-const keyValues = args => {
-  const kv = {}
-  for (let i = 0; i < args.length; i++) {
-    const arg = args[i].split('=')
-    const key = arg.shift()
-    const val = arg.length ? arg.join('=')
-      : i < args.length - 1 ? args[++i]
-      : ''
-    kv[key.trim()] = val.trim()
+  exec (args, cb) {
+    this.config(args).then(() => cb()).catch(cb)
   }
-  return kv
-}
-
-const set = async (args) => {
-  if (!args.length)
-    throw UsageError()
 
-  const where = npm.flatOptions.global ? 'global' : 'user'
-  for (const [key, val] of Object.entries(keyValues(args))) {
-    npm.log.info('config', 'set %j %j', key, val)
-    npm.config.set(key, val || '', where)
-    if (!npm.config.validate(where))
-      npm.log.warn('config', 'omitting invalid config values')
+  async config ([action, ...args]) {
+    this.npm.log.disableProgress()
+    try {
+      switch (action) {
+        case 'set':
+          await this.set(args)
+          break
+        case 'get':
+          await this.get(args)
+          break
+        case 'delete':
+        case 'rm':
+        case 'del':
+          await this.del(args)
+          break
+        case 'list':
+        case 'ls':
+          await (this.npm.flatOptions.json ? this.listJson() : this.list())
+          break
+        case 'edit':
+          await this.edit()
+          break
+        default:
+          throw this.usageError()
+      }
+    } finally {
+      this.npm.log.enableProgress()
+    }
   }
 
-  await npm.config.save(where)
-}
+  async set (args) {
+    if (!args.length)
+      throw this.usageError()
+
+    const where = this.npm.flatOptions.global ? 'global' : 'user'
+    for (const [key, val] of Object.entries(keyValues(args))) {
+      this.npm.log.info('config', 'set %j %j', key, val)
+      this.npm.config.set(key, val || '', where)
+      if (!this.npm.config.validate(where))
+        this.npm.log.warn('config', 'omitting invalid config values')
+    }
+
+    await this.npm.config.save(where)
+  }
 
-const get = async keys => {
-  if (!keys.length)
-    return list()
+  async get (keys) {
+    if (!keys.length)
+      return this.list()
 
-  const out = []
-  for (const key of keys) {
-    if (!publicVar(key))
-      throw `The ${key} option is protected, and cannot be retrieved in this way`
+    const out = []
+    for (const key of keys) {
+      if (!publicVar(key))
+        throw `The ${key} option is protected, and cannot be retrieved in this way`
 
-    const pref = keys.length > 1 ? `${key}=` : ''
-    out.push(pref + npm.config.get(key))
+      const pref = keys.length > 1 ? `${key}=` : ''
+      out.push(pref + this.npm.config.get(key))
+    }
+    output(out.join('\n'))
   }
-  output(out.join('\n'))
-}
 
-const del = async keys => {
-  if (!keys.length)
-    throw UsageError()
+  async del (keys) {
+    if (!keys.length)
+      throw this.usageError()
 
-  const where = npm.flatOptions.global ? 'global' : 'user'
-  for (const key of keys)
-    npm.config.delete(key, where)
-  await npm.config.save(where)
-}
+    const where = this.npm.flatOptions.global ? 'global' : 'user'
+    for (const key of keys)
+      this.npm.config.delete(key, where)
+    await this.npm.config.save(where)
+  }
 
-const edit = async () => {
-  const { editor: e, global } = npm.flatOptions
-  const where = global ? 'global' : 'user'
-  const file = npm.config.data.get(where).source
-
-  // save first, just to make sure it's synced up
-  // this also removes all the comments from the last time we edited it.
-  await npm.config.save(where)
-
-  const data = (
-    await readFile(file, 'utf8').catch(() => '')
-  ).replace(/\r\n/g, '\n')
-  const defData = Object.entries(defaults).reduce((str, [key, val]) => {
-    const obj = { [key]: val }
-    const i = ini.stringify(obj)
-      .replace(/\r\n/g, '\n') // normalizes output from ini.stringify
-      .replace(/\n$/m, '')
-      .replace(/^/g, '; ')
-      .replace(/\n/g, '\n; ')
-      .split('\n')
-    return str + '\n' + i
-  }, '')
-
-  const tmpData = `;;;;
+  async edit () {
+    const { editor: e, global } = this.npm.flatOptions
+    const where = global ? 'global' : 'user'
+    const file = this.npm.config.data.get(where).source
+
+    // save first, just to make sure it's synced up
+    // this also removes all the comments from the last time we edited it.
+    await this.npm.config.save(where)
+
+    const data = (
+      await readFile(file, 'utf8').catch(() => '')
+    ).replace(/\r\n/g, '\n')
+    const defData = Object.entries(defaults).reduce((str, [key, val]) => {
+      const obj = { [key]: val }
+      const i = ini.stringify(obj)
+        .replace(/\r\n/g, '\n') // normalizes output from ini.stringify
+        .replace(/\n$/m, '')
+        .replace(/^/g, '; ')
+        .replace(/\n/g, '\n; ')
+        .split('\n')
+      return str + '\n' + i
+    }, '')
+
+    const tmpData = `;;;;
 ; npm ${where}config file: ${file}
 ; this is a simple ini-formatted file
 ; lines that start with semi-colons are comments
@@ -190,64 +180,84 @@ ${data.split('\n').sort((a, b) => a.localeCompare(b)).join('\n').trim()}
 
 ${defData}
 `.split('\n').join(EOL)
-  await mkdirp(dirname(file))
-  await writeFile(file, tmpData, 'utf8')
-  await new Promise((resolve, reject) => {
-    const [bin, ...args] = e.split(/\s+/)
-    const editor = spawn(bin, [...args, file], { stdio: 'inherit' })
-    editor.on('exit', (code) => {
-      if (code)
-        return reject(new Error(`editor process exited with code: ${code}`))
-      return resolve()
+    await mkdirp(dirname(file))
+    await writeFile(file, tmpData, 'utf8')
+    await new Promise((resolve, reject) => {
+      const [bin, ...args] = e.split(/\s+/)
+      const editor = spawn(bin, [...args, file], { stdio: 'inherit' })
+      editor.on('exit', (code) => {
+        if (code)
+          return reject(new Error(`editor process exited with code: ${code}`))
+        return resolve()
+      })
     })
-  })
-}
-
-const publicVar = k => !/^(\/\/[^:]+:)?_/.test(k)
+  }
 
-const list = async () => {
-  const msg = []
-  const { long } = npm.flatOptions
-  for (const [where, { data, source }] of npm.config.data.entries()) {
-    if (where === 'default' && !long)
-      continue
+  async list () {
+    const msg = []
+    const { long } = this.npm.flatOptions
+    for (const [where, { data, source }] of this.npm.config.data.entries()) {
+      if (where === 'default' && !long)
+        continue
+
+      const keys = Object.keys(data).sort((a, b) => a.localeCompare(b))
+      if (!keys.length)
+        continue
+
+      msg.push(`; "${where}" config from ${source}`, '')
+      for (const k of keys) {
+        const v = publicVar(k) ? JSON.stringify(data[k]) : '(protected)'
+        const src = this.npm.config.find(k)
+        const overridden = src !== where
+        msg.push((overridden ? '; ' : '') +
+          `${k} = ${v} ${overridden ? `; overridden by ${src}` : ''}`)
+      }
+      msg.push('')
+    }
 
-    const keys = Object.keys(data).sort((a, b) => a.localeCompare(b))
-    if (!keys.length)
-      continue
-
-    msg.push(`; "${where}" config from ${source}`, '')
-    for (const k of keys) {
-      const v = publicVar(k) ? JSON.stringify(data[k]) : '(protected)'
-      const src = npm.config.find(k)
-      const overridden = src !== where
-      msg.push((overridden ? '; ' : '') +
-        `${k} = ${v} ${overridden ? `; overridden by ${src}` : ''}`)
+    if (!long) {
+      msg.push(
+        `; node bin location = ${process.execPath}`,
+        `; cwd = ${process.cwd()}`,
+        `; HOME = ${process.env.HOME}`,
+        '; Run `npm config ls -l` to show all defaults.'
+      )
     }
-    msg.push('')
+
+    output(msg.join('\n').trim())
   }
 
-  if (!long) {
-    msg.push(
-      `; node bin location = ${process.execPath}`,
-      `; cwd = ${process.cwd()}`,
-      `; HOME = ${process.env.HOME}`,
-      '; Run `npm config ls -l` to show all defaults.'
-    )
+  async listJson () {
+    const publicConf = {}
+    for (const key in this.npm.config.list[0]) {
+      if (!publicVar(key))
+        continue
+
+      publicConf[key] = this.npm.config.get(key)
+    }
+    output(JSON.stringify(publicConf, null, 2))
   }
 
-  output(msg.join('\n').trim())
+  usageError () {
+    return Object.assign(new Error(this.usage), { code: 'EUSAGE' })
+  }
 }
 
-const listJson = async () => {
-  const publicConf = {}
-  for (const key in npm.config.list[0]) {
-    if (!publicVar(key))
-      continue
-
-    publicConf[key] = npm.config.get(key)
+// take an array of `[key, value, k2=v2, k3, v3, ...]` and turn into
+// { key: value, k2: v2, k3: v3 }
+const keyValues = args => {
+  const kv = {}
+  for (let i = 0; i < args.length; i++) {
+    const arg = args[i].split('=')
+    const key = arg.shift()
+    const val = arg.length ? arg.join('=')
+      : i < args.length - 1 ? args[++i]
+      : ''
+    kv[key.trim()] = val.trim()
   }
-  output(JSON.stringify(publicConf, null, 2))
+  return kv
 }
 
-module.exports = Object.assign(cmd, { usage, completion })
+const publicVar = k => !/^(\/\/[^:]+:)?_/.test(k)
+
+module.exports = Config
diff --git a/lib/dedupe.js b/lib/dedupe.js
index 2211fcac8b481..f4abf48926b86 100644
--- a/lib/dedupe.js
+++ b/lib/dedupe.js
@@ -1,29 +1,38 @@
 // dedupe duplicated packages, or find them in the tree
-const npm = require('./npm.js')
 const Arborist = require('@npmcli/arborist')
 const usageUtil = require('./utils/usage.js')
 const reifyFinish = require('./utils/reify-finish.js')
 
-const usage = usageUtil('dedupe', 'npm dedupe')
+class Dedupe {
+  constructor (npm) {
+    this.npm = npm
+  }
 
-const cmd = (args, cb) => dedupe(args).then(() => cb()).catch(cb)
+  get usage () {
+    return usageUtil('dedupe', 'npm dedupe')
+  }
 
-const dedupe = async (args) => {
-  if (npm.flatOptions.global) {
-    const er = new Error('`npm dedupe` does not work in global mode.')
-    er.code = 'EDEDUPEGLOBAL'
-    throw er
+  exec (args, cb) {
+    this.dedupe(args).then(() => cb()).catch(cb)
   }
 
-  const dryRun = (args && args.dryRun) || npm.flatOptions.dryRun
-  const where = npm.prefix
-  const arb = new Arborist({
-    ...npm.flatOptions,
-    path: where,
-    dryRun,
-  })
-  await arb.dedupe(npm.flatOptions)
-  await reifyFinish(arb)
+  async dedupe (args) {
+    if (this.npm.flatOptions.global) {
+      const er = new Error('`npm dedupe` does not work in global mode.')
+      er.code = 'EDEDUPEGLOBAL'
+      throw er
+    }
+
+    const dryRun = (args && args.dryRun) || this.npm.flatOptions.dryRun
+    const where = this.npm.prefix
+    const arb = new Arborist({
+      ...this.npm.flatOptions,
+      path: where,
+      dryRun,
+    })
+    await arb.dedupe(this.npm.flatOptions)
+    await reifyFinish(arb)
+  }
 }
 
-module.exports = Object.assign(cmd, { usage })
+module.exports = Dedupe
diff --git a/lib/deprecate.js b/lib/deprecate.js
index 42d099b544e31..6de9cefe3f2d0 100644
--- a/lib/deprecate.js
+++ b/lib/deprecate.js
@@ -1,4 +1,3 @@
-const npm = require('./npm.js')
 const fetch = require('npm-registry-fetch')
 const otplease = require('./utils/otplease.js')
 const npa = require('npm-package-arg')
@@ -7,67 +6,77 @@ const getIdentity = require('./utils/get-identity.js')
 const libaccess = require('libnpmaccess')
 const usageUtil = require('./utils/usage.js')
 
-const UsageError = () =>
-  Object.assign(new Error(`\nUsage: ${usage}`), {
-    code: 'EUSAGE',
-  })
+class Deprecate {
+  constructor (npm) {
+    this.npm = npm
+  }
 
-const usage = usageUtil(
-  'deprecate',
-  'npm deprecate <pkg>[@<version>] <message>'
-)
+  get usage () {
+    return usageUtil(
+      'deprecate',
+      'npm deprecate <pkg>[@<version>] <message>'
+    )
+  }
 
-const completion = async (opts) => {
-  if (opts.conf.argv.remain.length > 1)
-    return []
+  async completion (opts) {
+    if (opts.conf.argv.remain.length > 1)
+      return []
 
-  const username = await getIdentity(npm.flatOptions)
-  const packages = await libaccess.lsPackages(username, npm.flatOptions)
-  return Object.keys(packages)
-    .filter((name) =>
-      packages[name] === 'write' &&
-      (opts.conf.argv.remain.length === 0 ||
-        name.startsWith(opts.conf.argv.remain[0])))
-}
-
-const cmd = (args, cb) =>
-  deprecate(args)
-    .then(() => cb())
-    .catch(err => cb(err.code === 'EUSAGE' ? err.message : err))
+    const username = await getIdentity(this.npm.flatOptions)
+    const packages = await libaccess.lsPackages(username, this.npm.flatOptions)
+    return Object.keys(packages)
+      .filter((name) =>
+        packages[name] === 'write' &&
+        (opts.conf.argv.remain.length === 0 ||
+          name.startsWith(opts.conf.argv.remain[0])))
+  }
 
-const deprecate = async ([pkg, msg]) => {
-  if (!pkg || !msg)
-    throw UsageError()
+  exec (args, cb) {
+    this.deprecate(args)
+      .then(() => cb())
+      .catch(err => cb(err.code === 'EUSAGE' ? err.message : err))
+  }
 
-  // fetch the data and make sure it exists.
-  const p = npa(pkg)
-  // npa makes the default spec "latest", but for deprecation
-  // "*" is the appropriate default.
-  const spec = p.rawSpec === '' ? '*' : p.fetchSpec
+  async deprecate ([pkg, msg]) {
+    if (!pkg || !msg)
+      throw this.usageError()
 
-  if (semver.validRange(spec, true) === null)
-    throw new Error(`invalid version range: ${spec}`)
+    // fetch the data and make sure it exists.
+    const p = npa(pkg)
+    // npa makes the default spec "latest", but for deprecation
+    // "*" is the appropriate default.
+    const spec = p.rawSpec === '' ? '*' : p.fetchSpec
 
-  const uri = '/' + p.escapedName
-  const packument = await fetch.json(uri, {
-    ...npm.flatOptions,
-    spec: p,
-    query: { write: true },
-  })
+    if (semver.validRange(spec, true) === null)
+      throw new Error(`invalid version range: ${spec}`)
 
-  Object.keys(packument.versions)
-    .filter(v => semver.satisfies(v, spec, { includePrerelease: true }))
-    .forEach(v => {
-      packument.versions[v].deprecated = msg
+    const uri = '/' + p.escapedName
+    const packument = await fetch.json(uri, {
+      ...this.npm.flatOptions,
+      spec: p,
+      query: { write: true },
     })
 
-  return otplease(npm.flatOptions, opts => fetch(uri, {
-    ...opts,
-    spec: p,
-    method: 'PUT',
-    body: packument,
-    ignoreBody: true,
-  }))
+    Object.keys(packument.versions)
+      .filter(v => semver.satisfies(v, spec, { includePrerelease: true }))
+      .forEach(v => {
+        packument.versions[v].deprecated = msg
+      })
+
+    return otplease(this.npm.flatOptions, opts => fetch(uri, {
+      ...opts,
+      spec: p,
+      method: 'PUT',
+      body: packument,
+      ignoreBody: true,
+    }))
+  }
+
+  usageError () {
+    return Object.assign(new Error(`\nUsage: ${this.usage}`), {
+      code: 'EUSAGE',
+    })
+  }
 }
 
-module.exports = Object.assign(cmd, { completion, usage })
+module.exports = Deprecate
diff --git a/lib/diff.js b/lib/diff.js
index 9ef5a78a20ce9..ea0340a4909d2 100644
--- a/lib/diff.js
+++ b/lib/diff.js
@@ -8,258 +8,270 @@ const npmlog = require('npmlog')
 const pacote = require('pacote')
 const pickManifest = require('npm-pick-manifest')
 
-const npm = require('./npm.js')
 const usageUtil = require('./utils/usage.js')
 const output = require('./utils/output.js')
 const readLocalPkg = require('./utils/read-local-package.js')
 
-const usage = usageUtil(
-  'diff',
-  'npm diff [...<paths>]' +
-  '\nnpm diff --diff=<pkg-name> [...<paths>]' +
-  '\nnpm diff --diff=<version-a> [--diff=<version-b>] [...<paths>]' +
-  '\nnpm diff --diff=<spec-a> [--diff=<spec-b>] [...<paths>]' +
-  '\nnpm diff [--diff-ignore-all-space] [--diff-name-only] [...<paths>] [...<paths>]'
-)
-
-const cmd = (args, cb) => diff(args).then(() => cb()).catch(cb)
-
-const where = () => {
-  const globalTop = resolve(npm.globalDir, '..')
-  const { global } = npm.flatOptions
-  return global ? globalTop : npm.prefix
-}
+class Diff {
+  constructor (npm) {
+    this.npm = npm
+  }
 
-const diff = async (args) => {
-  const specs = npm.flatOptions.diff.filter(d => d)
-  if (specs.length > 2) {
-    throw new TypeError(
-      'Can\'t use more than two --diff arguments.\n\n' +
-      `Usage:\n${usage}`
+  get usage () {
+    return usageUtil(
+      'diff',
+      'npm diff [...<paths>]' +
+      '\nnpm diff --diff=<pkg-name> [...<paths>]' +
+      '\nnpm diff --diff=<version-a> [--diff=<version-b>] [...<paths>]' +
+      '\nnpm diff --diff=<spec-a> [--diff=<spec-b>] [...<paths>]' +
+      '\nnpm diff [--diff-ignore-all-space] [--diff-name-only] [...<paths>] [...<paths>]'
     )
   }
 
-  const [a, b] = await retrieveSpecs(specs)
-  npmlog.info('diff', { src: a, dst: b })
-
-  const res = await libdiff([a, b], { ...npm.flatOptions, diffFiles: args })
-  return output(res)
-}
-
-const retrieveSpecs = ([a, b]) => {
-  // no arguments, defaults to comparing cwd
-  // to its latest published registry version
-  if (!a)
-    return defaultSpec()
+  get where () {
+    const globalTop = resolve(this.npm.globalDir, '..')
+    const { global } = this.npm.flatOptions
+    return global ? globalTop : this.npm.prefix
+  }
 
-  // single argument, used to compare wanted versions of an
-  // installed dependency or to compare the cwd to a published version
-  if (!b)
-    return transformSingleSpec(a)
+  exec (args, cb) {
+    this.diff(args).then(() => cb()).catch(cb)
+  }
 
-  return convertVersionsToSpecs([a, b])
-    .then(findVersionsByPackageName)
-}
+  async diff (args) {
+    const specs = this.npm.flatOptions.diff.filter(d => d)
+    if (specs.length > 2) {
+      throw new TypeError(
+        'Can\'t use more than two --diff arguments.\n\n' +
+        `Usage:\n${this.usage}`
+      )
+    }
 
-const defaultSpec = async () => {
-  let noPackageJson
-  let pkgName
-  try {
-    pkgName = await readLocalPkg()
-  } catch (e) {
-    npmlog.verbose('diff', 'could not read project dir package.json')
-    noPackageJson = true
-  }
+    const [a, b] = await this.retrieveSpecs(specs)
+    npmlog.info('diff', { src: a, dst: b })
 
-  if (!pkgName || noPackageJson) {
-    throw new Error(
-      'Needs multiple arguments to compare or run from a project dir.\n\n' +
-      `Usage:\n${usage}`
+    const res = await libdiff(
+      [a, b],
+      { ...this.npm.flatOptions, diffFiles: args }
     )
+    return output(res)
   }
 
-  return [
-    `${pkgName}@${npm.flatOptions.defaultTag}`,
-    `file:${npm.prefix}`,
-  ]
-}
+  async retrieveSpecs ([a, b]) {
+    // no arguments, defaults to comparing cwd
+    // to its latest published registry version
+    if (!a)
+      return this.defaultSpec()
 
-const transformSingleSpec = async (a) => {
-  let noPackageJson
-  let pkgName
-  try {
-    pkgName = await readLocalPkg()
-  } catch (e) {
-    npmlog.verbose('diff', 'could not read project dir package.json')
-    noPackageJson = true
-  }
-  const missingPackageJson = new Error(
-    'Needs multiple arguments to compare or run from a project dir.\n\n' +
-    `Usage:\n${usage}`
-  )
+    // single argument, used to compare wanted versions of an
+    // installed dependency or to compare the cwd to a published version
+    if (!b)
+      return this.transformSingleSpec(a)
 
-  const specSelf = () => {
-    if (noPackageJson)
-      throw missingPackageJson
-
-    return `file:${npm.prefix}`
+    const specs = await this.convertVersionsToSpecs([a, b])
+    return this.findVersionsByPackageName(specs)
   }
 
-  // using a valid semver range, that means it should just diff
-  // the cwd against a published version to the registry using the
-  // same project name and the provided semver range
-  if (semver.validRange(a)) {
-    if (!pkgName)
-      throw missingPackageJson
+  async defaultSpec () {
+    let noPackageJson
+    let pkgName
+    try {
+      pkgName = await readLocalPkg(this.npm)
+    } catch (e) {
+      npmlog.verbose('diff', 'could not read project dir package.json')
+      noPackageJson = true
+    }
+
+    if (!pkgName || noPackageJson) {
+      throw new Error(
+        'Needs multiple arguments to compare or run from a project dir.\n\n' +
+        `Usage:\n${this.usage}`
+      )
+    }
 
     return [
-      `${pkgName}@${a}`,
-      specSelf(),
+      `${pkgName}@${this.npm.flatOptions.defaultTag}`,
+      `file:${this.npm.prefix}`,
     ]
   }
 
-  // when using a single package name as arg and it's part of the current
-  // install tree, then retrieve the current installed version and compare
-  // it against the same value `npm outdated` would suggest you to update to
-  const spec = npa(a)
-  if (spec.registry) {
-    let actualTree
-    let node
+  async transformSingleSpec (a) {
+    let noPackageJson
+    let pkgName
     try {
-      const opts = {
-        ...npm.flatOptions,
-        path: where(),
-      }
-      const arb = new Arborist(opts)
-      actualTree = await arb.loadActual(opts)
-      node = actualTree &&
-        actualTree.inventory.query('name', spec.name)
-          .values().next().value
+      pkgName = await readLocalPkg(this.npm)
     } catch (e) {
-      npmlog.verbose('diff', 'failed to load actual install tree')
+      npmlog.verbose('diff', 'could not read project dir package.json')
+      noPackageJson = true
+    }
+    const missingPackageJson = new Error(
+      'Needs multiple arguments to compare or run from a project dir.\n\n' +
+      `Usage:\n${this.usage}`
+    )
+
+    const specSelf = () => {
+      if (noPackageJson)
+        throw missingPackageJson
+
+      return `file:${this.npm.prefix}`
     }
 
-    if (!node || !node.name || !node.package || !node.package.version) {
+    // using a valid semver range, that means it should just diff
+    // the cwd against a published version to the registry using the
+    // same project name and the provided semver range
+    if (semver.validRange(a)) {
+      if (!pkgName)
+        throw missingPackageJson
+
       return [
-        `${spec.name}@${spec.fetchSpec}`,
+        `${pkgName}@${a}`,
         specSelf(),
       ]
     }
 
-    const tryRootNodeSpec = () =>
-      (actualTree && actualTree.edgesOut.get(spec.name) || {}).spec
-
-    const tryAnySpec = () => {
-      for (const edge of node.edgesIn)
-        return edge.spec
-    }
+    // when using a single package name as arg and it's part of the current
+    // install tree, then retrieve the current installed version and compare
+    // it against the same value `npm outdated` would suggest you to update to
+    const spec = npa(a)
+    if (spec.registry) {
+      let actualTree
+      let node
+      try {
+        const opts = {
+          ...this.npm.flatOptions,
+          path: this.where,
+        }
+        const arb = new Arborist(opts)
+        actualTree = await arb.loadActual(opts)
+        node = actualTree &&
+          actualTree.inventory.query('name', spec.name)
+            .values().next().value
+      } catch (e) {
+        npmlog.verbose('diff', 'failed to load actual install tree')
+      }
 
-    const aSpec = `file:${node.realpath}`
-
-    // finds what version of the package to compare against, if a exact
-    // version or tag was passed than it should use that, otherwise
-    // work from the top of the arborist tree to find the original semver
-    // range declared in the package that depends on the package.
-    let bSpec
-    if (spec.rawSpec)
-      bSpec = spec.rawSpec
-    else {
-      const bTargetVersion =
-        tryRootNodeSpec()
-        || tryAnySpec()
-
-      // figure out what to compare against,
-      // follows same logic to npm outdated "Wanted" results
-      const packument = await pacote.packument(spec, {
-        ...npm.flatOptions,
-        preferOnline: true,
-      })
-      bSpec = pickManifest(
-        packument,
-        bTargetVersion,
-        { ...npm.flatOptions }
-      ).version
-    }
+      if (!node || !node.name || !node.package || !node.package.version) {
+        return [
+          `${spec.name}@${spec.fetchSpec}`,
+          specSelf(),
+        ]
+      }
 
-    return [
-      `${spec.name}@${aSpec}`,
-      `${spec.name}@${bSpec}`,
-    ]
-  } else if (spec.type === 'directory') {
-    return [
-      `file:${spec.fetchSpec}`,
-      specSelf(),
-    ]
-  } else {
-    throw new Error(
-      'Spec type not supported.\n\n' +
-      `Usage:\n${usage}`
-    )
-  }
-}
+      const tryRootNodeSpec = () =>
+        (actualTree && actualTree.edgesOut.get(spec.name) || {}).spec
 
-const convertVersionsToSpecs = async ([a, b]) => {
-  const semverA = semver.validRange(a)
-  const semverB = semver.validRange(b)
+      const tryAnySpec = () => {
+        for (const edge of node.edgesIn)
+          return edge.spec
+      }
 
-  // both specs are semver versions, assume current project dir name
-  if (semverA && semverB) {
-    let pkgName
-    try {
-      pkgName = await readLocalPkg()
-    } catch (e) {
-      npmlog.verbose('diff', 'could not read project dir package.json')
-    }
+      const aSpec = `file:${node.realpath}`
+
+      // finds what version of the package to compare against, if a exact
+      // version or tag was passed than it should use that, otherwise
+      // work from the top of the arborist tree to find the original semver
+      // range declared in the package that depends on the package.
+      let bSpec
+      if (spec.rawSpec)
+        bSpec = spec.rawSpec
+      else {
+        const bTargetVersion =
+          tryRootNodeSpec()
+          || tryAnySpec()
+
+        // figure out what to compare against,
+        // follows same logic to npm outdated "Wanted" results
+        const packument = await pacote.packument(spec, {
+          ...this.npm.flatOptions,
+          preferOnline: true,
+        })
+        bSpec = pickManifest(
+          packument,
+          bTargetVersion,
+          { ...this.npm.flatOptions }
+        ).version
+      }
 
-    if (!pkgName) {
+      return [
+        `${spec.name}@${aSpec}`,
+        `${spec.name}@${bSpec}`,
+      ]
+    } else if (spec.type === 'directory') {
+      return [
+        `file:${spec.fetchSpec}`,
+        specSelf(),
+      ]
+    } else {
       throw new Error(
-        'Needs to be run from a project dir in order to diff two versions.\n\n' +
-        `Usage:\n${usage}`
+        'Spec type not supported.\n\n' +
+        `Usage:\n${this.usage}`
       )
     }
-    return [`${pkgName}@${a}`, `${pkgName}@${b}`]
   }
 
-  // otherwise uses the name from the other arg to
-  // figure out the spec.name of what to compare
-  if (!semverA && semverB)
-    return [a, `${npa(a).name}@${b}`]
+  async convertVersionsToSpecs ([a, b]) {
+    const semverA = semver.validRange(a)
+    const semverB = semver.validRange(b)
+
+    // both specs are semver versions, assume current project dir name
+    if (semverA && semverB) {
+      let pkgName
+      try {
+        pkgName = await readLocalPkg(this.npm)
+      } catch (e) {
+        npmlog.verbose('diff', 'could not read project dir package.json')
+      }
+
+      if (!pkgName) {
+        throw new Error(
+          'Needs to be run from a project dir in order to diff two versions.\n\n' +
+          `Usage:\n${this.usage}`
+        )
+      }
+      return [`${pkgName}@${a}`, `${pkgName}@${b}`]
+    }
 
-  if (semverA && !semverB)
-    return [`${npa(b).name}@${a}`, b]
+    // otherwise uses the name from the other arg to
+    // figure out the spec.name of what to compare
+    if (!semverA && semverB)
+      return [a, `${npa(a).name}@${b}`]
 
-  // no valid semver ranges used
-  return [a, b]
-}
+    if (semverA && !semverB)
+      return [`${npa(b).name}@${a}`, b]
 
-const findVersionsByPackageName = async (specs) => {
-  let actualTree
-  try {
-    const opts = {
-      ...npm.flatOptions,
-      path: where(),
-    }
-    const arb = new Arborist(opts)
-    actualTree = await arb.loadActual(opts)
-  } catch (e) {
-    npmlog.verbose('diff', 'failed to load actual install tree')
+    // no valid semver ranges used
+    return [a, b]
   }
 
-  return specs.map(i => {
-    const spec = npa(i)
-    if (spec.rawSpec)
-      return i
+  async findVersionsByPackageName (specs) {
+    let actualTree
+    try {
+      const opts = {
+        ...this.npm.flatOptions,
+        path: this.where,
+      }
+      const arb = new Arborist(opts)
+      actualTree = await arb.loadActual(opts)
+    } catch (e) {
+      npmlog.verbose('diff', 'failed to load actual install tree')
+    }
+
+    return specs.map(i => {
+      const spec = npa(i)
+      if (spec.rawSpec)
+        return i
 
-    const node = actualTree
-      && actualTree.inventory.query('name', spec.name)
-        .values().next().value
+      const node = actualTree
+        && actualTree.inventory.query('name', spec.name)
+          .values().next().value
 
-    const res = !node || !node.package || !node.package.version
-      ? spec.fetchSpec
-      : `file:${node.realpath}`
+      const res = !node || !node.package || !node.package.version
+        ? spec.fetchSpec
+        : `file:${node.realpath}`
 
-    return `${spec.name}@${res}`
-  })
+      return `${spec.name}@${res}`
+    })
+  }
 }
 
-module.exports = Object.assign(cmd, { usage })
+module.exports = Diff
diff --git a/lib/utils/read-local-package.js b/lib/utils/read-local-package.js
index 7ab130c1f31b0..c31bca994704c 100644
--- a/lib/utils/read-local-package.js
+++ b/lib/utils/read-local-package.js
@@ -1,8 +1,6 @@
 const { resolve } = require('path')
 const readJson = require('read-package-json-fast')
-const npm = require('../npm.js')
-
-async function readLocalPackageName (cb) {
+async function readLocalPackageName (npm) {
   if (npm.flatOptions.global)
     return
 
diff --git a/test/lib/config.js b/test/lib/config.js
index edaa6486cdc95..c2420aefb4a00 100644
--- a/test/lib/config.js
+++ b/test/lib/config.js
@@ -68,17 +68,17 @@ const usageUtil = () => 'usage instructions'
 
 const mocks = {
   '../../lib/utils/config.js': { defaults, types },
-  '../../lib/npm.js': npm,
   '../../lib/utils/output.js': msg => {
     result = msg
   },
   '../../lib/utils/usage.js': usageUtil,
 }
 
-const config = requireInject('../../lib/config.js', mocks)
+const Config = requireInject('../../lib/config.js', mocks)
+const config = new Config(npm)
 
 t.test('config no args', t => {
-  config([], (err) => {
+  config.exec([], (err) => {
     t.match(err, /usage instructions/, 'should not error out on empty locations')
     t.end()
   })
@@ -94,7 +94,7 @@ t.test('config list', t => {
     delete npm.config.find
   })
 
-  config(['list'], (err) => {
+  config.exec(['list'], (err) => {
     t.ifError(err, 'npm config list')
     t.matchSnapshot(result, 'should list configs')
   })
@@ -120,7 +120,7 @@ t.test('config list overrides', t => {
     delete npm.config.find
   })
 
-  config(['list'], (err) => {
+  config.exec(['list'], (err) => {
     t.ifError(err, 'npm config list')
     t.matchSnapshot(result, 'should list overridden configs')
   })
@@ -138,7 +138,7 @@ t.test('config list --long', t => {
     result = ''
   })
 
-  config(['list'], (err) => {
+  config.exec(['list'], (err) => {
     t.ifError(err, 'npm config list --long')
     t.matchSnapshot(result, 'should list all configs')
   })
@@ -163,7 +163,7 @@ t.test('config list --json', t => {
     result = ''
   })
 
-  config(['list'], (err) => {
+  config.exec(['list'], (err) => {
     t.ifError(err, 'npm config list --json')
     t.deepEqual(
       JSON.parse(result),
@@ -179,7 +179,7 @@ t.test('config list --json', t => {
 })
 
 t.test('config delete no args', t => {
-  config(['delete'], (err) => {
+  config.exec(['delete'], (err) => {
     t.equal(
       err.message,
       'usage instructions',
@@ -202,7 +202,7 @@ t.test('config delete key', t => {
     t.equal(where, 'user', 'should save user config post-delete')
   }
 
-  config(['delete', 'foo'], (err) => {
+  config.exec(['delete', 'foo'], (err) => {
     t.ifError(err, 'npm config delete key')
   })
 
@@ -229,7 +229,7 @@ t.test('config delete multiple key', t => {
     t.equal(where, 'user', 'should save user config post-delete')
   }
 
-  config(['delete', 'foo', 'bar'], (err) => {
+  config.exec(['delete', 'foo', 'bar'], (err) => {
     t.ifError(err, 'npm config delete keys')
   })
 
@@ -252,7 +252,7 @@ t.test('config delete key --global', t => {
   }
 
   flatOptions.global = true
-  config(['delete', 'foo'], (err) => {
+  config.exec(['delete', 'foo'], (err) => {
     t.ifError(err, 'npm config delete key --global')
   })
 
@@ -264,7 +264,7 @@ t.test('config delete key --global', t => {
 })
 
 t.test('config set no args', t => {
-  config(['set'], (err) => {
+  config.exec(['set'], (err) => {
     t.equal(
       err.message,
       'usage instructions',
@@ -287,7 +287,7 @@ t.test('config set key', t => {
     t.equal(where, 'user', 'should save user config')
   }
 
-  config(['set', 'foo', 'bar'], (err) => {
+  config.exec(['set', 'foo', 'bar'], (err) => {
     t.ifError(err, 'npm config set key')
   })
 
@@ -310,7 +310,7 @@ t.test('config set key=val', t => {
     t.equal(where, 'user', 'should save user config')
   }
 
-  config(['set', 'foo=bar'], (err) => {
+  config.exec(['set', 'foo=bar'], (err) => {
     t.ifError(err, 'npm config set key')
   })
 
@@ -341,7 +341,7 @@ t.test('config set multiple keys', t => {
     t.equal(where, 'user', 'should save user config')
   }
 
-  config(['set', ...args], (err) => {
+  config.exec(['set', ...args], (err) => {
     t.ifError(err, 'npm config set key')
   })
 
@@ -364,7 +364,7 @@ t.test('config set key to empty value', t => {
     t.equal(where, 'user', 'should save user config')
   }
 
-  config(['set', 'foo'], (err) => {
+  config.exec(['set', 'foo'], (err) => {
     t.ifError(err, 'npm config set key to empty value')
   })
 
@@ -392,7 +392,7 @@ t.test('config set invalid key', t => {
     delete npm.log.warn
   })
 
-  config(['set', 'foo', 'bar'], (err) => {
+  config.exec(['set', 'foo', 'bar'], (err) => {
     t.ifError(err, 'npm config set invalid key')
   })
 })
@@ -411,7 +411,7 @@ t.test('config set key --global', t => {
   }
 
   flatOptions.global = true
-  config(['set', 'foo', 'bar'], (err) => {
+  config.exec(['set', 'foo', 'bar'], (err) => {
     t.ifError(err, 'npm config set key --global')
   })
 
@@ -432,7 +432,7 @@ t.test('config get no args', t => {
     delete npm.config.find
   })
 
-  config(['get'], (err) => {
+  config.exec(['get'], (err) => {
     t.ifError(err, 'npm config get no args')
     t.matchSnapshot(result, 'should list configs on config get no args')
   })
@@ -451,7 +451,7 @@ t.test('config get key', t => {
     throw new Error('should not save')
   }
 
-  config(['get', 'foo'], (err) => {
+  config.exec(['get', 'foo'], (err) => {
     t.ifError(err, 'npm config get key')
   })
 
@@ -479,7 +479,7 @@ t.test('config get multiple keys', t => {
     throw new Error('should not save')
   }
 
-  config(['get', 'foo', 'bar'], (err) => {
+  config.exec(['get', 'foo', 'bar'], (err) => {
     t.ifError(err, 'npm config get multiple keys')
     t.equal(result, 'foo=asdf\nbar=asdf')
   })
@@ -492,7 +492,7 @@ t.test('config get multiple keys', t => {
 })
 
 t.test('config get private key', t => {
-  config(['get', '//private-reg.npmjs.org/:_authThoken'], (err) => {
+  config.exec(['get', '//private-reg.npmjs.org/:_authThoken'], (err) => {
     t.match(
       err,
       /The \/\/private-reg.npmjs.org\/:_authThoken option is protected, and cannot be retrieved in this way/,
@@ -538,16 +538,19 @@ sign-git-commit=true`
       },
     },
   }
-  const config = requireInject('../../lib/config.js', editMocks)
-  config(['edit'], (err) => {
+  const Config = requireInject('../../lib/config.js', editMocks)
+  const config = new Config(npm)
+
+  config.exec(['edit'], (err) => {
     t.ifError(err, 'npm config edit')
 
     // test no config file result
     editMocks.fs.readFile = (p, e, cb) => {
       cb(new Error('ERR'))
     }
-    const config = requireInject('../../lib/config.js', editMocks)
-    config(['edit'], (err) => {
+    const Config = requireInject('../../lib/config.js', editMocks)
+    const config = new Config(npm)
+    config.exec(['edit'], (err) => {
       t.ifError(err, 'npm config edit')
     })
   })
@@ -594,8 +597,9 @@ t.test('config edit --global', t => {
       },
     },
   }
-  const config = requireInject('../../lib/config.js', editMocks)
-  config(['edit'], (err) => {
+  const Config = requireInject('../../lib/config.js', editMocks)
+  const config = new Config(npm)
+  config.exec(['edit'], (err) => {
     t.match(err, /exited with code: 137/, 'propagated exit code from editor')
   })
 
diff --git a/test/lib/dedupe.js b/test/lib/dedupe.js
index b14185525bbea..27cd583dd2c9a 100644
--- a/test/lib/dedupe.js
+++ b/test/lib/dedupe.js
@@ -2,28 +2,17 @@ const { test } = require('tap')
 const requireInject = require('require-inject')
 
 test('should throw in global mode', (t) => {
-  const dedupe = requireInject('../../lib/dedupe.js', {
-    '../../lib/npm.js': {
-      flatOptions: {
-        global: true,
-      },
-    },
-  })
+  const Dedupe = requireInject('../../lib/dedupe.js')
+  const dedupe = new Dedupe({ flatOptions: { global: true } })
 
-  dedupe([], er => {
+  dedupe.exec([], er => {
     t.match(er, { code: 'EDEDUPEGLOBAL' }, 'throws EDEDUPEGLOBAL')
     t.end()
   })
 })
 
 test('should remove dupes using Arborist', (t) => {
-  const dedupe = requireInject('../../lib/dedupe.js', {
-    '../../lib/npm.js': {
-      prefix: 'foo',
-      flatOptions: {
-        dryRun: 'false',
-      },
-    },
+  const Dedupe = requireInject('../../lib/dedupe.js', {
     '@npmcli/arborist': function (args) {
       t.ok(args, 'gets options object')
       t.ok(args.path, 'gets path option')
@@ -36,7 +25,13 @@ test('should remove dupes using Arborist', (t) => {
       t.ok(arb, 'gets arborist tree')
     },
   })
-  dedupe({ dryRun: true }, er => {
+  const dedupe = new Dedupe({
+    prefix: 'foo',
+    flatOptions: {
+      dryRun: 'false',
+    },
+  })
+  dedupe.exec({ dryRun: true }, er => {
     if (er)
       throw er
     t.ok(true, 'callback is called')
@@ -45,20 +40,20 @@ test('should remove dupes using Arborist', (t) => {
 })
 
 test('should remove dupes using Arborist - no arguments', (t) => {
-  const dedupe = requireInject('../../lib/dedupe.js', {
-    '../../lib/npm.js': {
-      prefix: 'foo',
-      flatOptions: {
-        dryRun: 'true',
-      },
-    },
+  const Dedupe = requireInject('../../lib/dedupe.js', {
     '@npmcli/arborist': function (args) {
       t.ok(args.dryRun, 'gets dryRun from flatOptions')
       this.dedupe = () => {}
     },
     '../../lib/utils/reify-output.js': () => {},
   })
-  dedupe(null, () => {
+  const dedupe = new Dedupe({
+    prefix: 'foo',
+    flatOptions: {
+      dryRun: 'true',
+    },
+  })
+  dedupe.exec(null, () => {
     t.end()
   })
 })
diff --git a/test/lib/deprecate.js b/test/lib/deprecate.js
index fd563de1209dd..03100166a012c 100644
--- a/test/lib/deprecate.js
+++ b/test/lib/deprecate.js
@@ -18,10 +18,7 @@ npmFetch.json = async (uri, opts) => {
   }
 }
 
-const deprecate = requireInject('../../lib/deprecate.js', {
-  '../../lib/npm.js': {
-    flatOptions: { registry: 'https://registry.npmjs.org' },
-  },
+const Deprecate = requireInject('../../lib/deprecate.js', {
   '../../lib/utils/get-identity.js': async () => getIdentityImpl(),
   '../../lib/utils/otplease.js': async (opts, fn) => fn(opts),
   libnpmaccess: {
@@ -30,16 +27,19 @@ const deprecate = requireInject('../../lib/deprecate.js', {
   'npm-registry-fetch': npmFetch,
 })
 
+const deprecate = new Deprecate({
+  flatOptions: { registry: 'https://registry.npmjs.org' },
+})
+
 test('completion', async t => {
   const defaultIdentityImpl = getIdentityImpl
   t.teardown(() => {
     getIdentityImpl = defaultIdentityImpl
   })
 
-  const { completion } = deprecate
-
   const testComp = async (argv, expect) => {
-    const res = await completion({ conf: { argv: { remain: argv } } })
+    const res =
+      await deprecate.completion({ conf: { argv: { remain: argv } } })
     t.strictSame(res, expect, `completion: ${argv}`)
   }
 
@@ -59,21 +59,21 @@ test('completion', async t => {
 })
 
 test('no args', t => {
-  deprecate([], (err) => {
+  deprecate.exec([], (err) => {
     t.match(err, /Usage: npm deprecate/, 'logs usage')
     t.end()
   })
 })
 
 test('only one arg', t => {
-  deprecate(['foo'], (err) => {
+  deprecate.exec(['foo'], (err) => {
     t.match(err, /Usage: npm deprecate/, 'logs usage')
     t.end()
   })
 })
 
 test('invalid semver range', t => {
-  deprecate(['foo@notaversion', 'this will fail'], (err) => {
+  deprecate.exec(['foo@notaversion', 'this will fail'], (err) => {
     t.match(err, /invalid version range/, 'logs semver error')
     t.end()
   })
@@ -84,7 +84,7 @@ test('deprecates given range', t => {
     npmFetchBody = null
   })
 
-  deprecate(['foo@1.0.0', 'this version is deprecated'], (err) => {
+  deprecate.exec(['foo@1.0.0', 'this version is deprecated'], (err) => {
     if (err)
       throw err
 
@@ -110,7 +110,7 @@ test('deprecates all versions when no range is specified', t => {
     npmFetchBody = null
   })
 
-  deprecate(['foo', 'this version is deprecated'], (err) => {
+  deprecate.exec(['foo', 'this version is deprecated'], (err) => {
     if (err)
       throw err
 
diff --git a/test/lib/diff.js b/test/lib/diff.js
index 926c54fdf1848..5e60f125cec3d 100644
--- a/test/lib/diff.js
+++ b/test/lib/diff.js
@@ -28,7 +28,6 @@ const mocks = {
   npmlog: { info: noop, verbose: noop },
   libnpmdiff: (...args) => libnpmdiff(...args),
   'npm-registry-fetch': async () => ({}),
-  '../../lib/npm.js': npm,
   '../../lib/utils/output.js': noop,
   '../../lib/utils/read-local-package.js': async () => rlp(),
   '../../lib/utils/usage.js': () => 'usage instructions',
@@ -42,7 +41,8 @@ t.afterEach(cb => {
   cb()
 })
 
-const diff = requireInject('../../lib/diff.js', mocks)
+const Diff = requireInject('../../lib/diff.js', mocks)
+const diff = new Diff(npm)
 
 t.test('no args', t => {
   t.test('in a project dir', t => {
@@ -56,7 +56,7 @@ t.test('no args', t => {
     }
 
     npm.flatOptions.prefix = path
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -65,7 +65,7 @@ t.test('no args', t => {
   t.test('no args, missing package.json name in cwd', t => {
     rlp = () => undefined
 
-    diff([], err => {
+    diff.exec([], err => {
       t.match(
         err,
         /Needs multiple arguments to compare or run from a project dir./,
@@ -80,7 +80,7 @@ t.test('no args', t => {
       throw new Error('ERR')
     }
 
-    diff([], err => {
+    diff.exec([], err => {
       t.match(
         err,
         /Needs multiple arguments to compare or run from a project dir./,
@@ -106,7 +106,7 @@ t.test('single arg', t => {
 
     npm.flatOptions.diff = ['foo@1.0.0']
     npm.flatOptions.prefix = path
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -120,7 +120,7 @@ t.test('single arg', t => {
 
     npm.flatOptions.diff = ['foo@1.0.0']
     npm.flatOptions.prefix = path
-    diff([], err => {
+    diff.exec([], err => {
       t.match(
         err,
         /Needs multiple arguments to compare or run from a project dir./,
@@ -142,7 +142,7 @@ t.test('single arg', t => {
 
     npm.flatOptions.diff = ['foo@~1.0.0']
     npm.flatOptions.prefix = path
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -160,7 +160,7 @@ t.test('single arg', t => {
 
     npm.flatOptions.diff = ['2.1.4']
     npm.flatOptions.prefix = path
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -172,7 +172,7 @@ t.test('single arg', t => {
     }
 
     npm.flatOptions.diff = ['2.1.4']
-    diff([], err => {
+    diff.exec([], err => {
       t.match(
         err,
         /Needs multiple arguments to compare or run from a project dir./,
@@ -200,7 +200,7 @@ t.test('single arg', t => {
 
     npm.flatOptions.diff = ['2.1.4']
     npm.flatOptions.prefix = path
-    diff(['./foo.js', './bar.js'], err => {
+    diff.exec(['./foo.js', './bar.js'], err => {
       if (err)
         throw err
     })
@@ -224,7 +224,7 @@ t.test('single arg', t => {
     npm.flatOptions.diff = ['bar@1.0.0']
     npm.flatOptions.prefix = path
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -250,7 +250,7 @@ t.test('single arg', t => {
 
     npm.flatOptions.diff = ['simple-output']
     npm.flatOptions.prefix = path
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -264,7 +264,7 @@ t.test('single arg', t => {
 
     npm.flatOptions.diff = ['bar']
     npm.flatOptions.prefix = path
-    diff([], err => {
+    diff.exec([], err => {
       t.match(
         err,
         /Needs multiple arguments to compare or run from a project dir./,
@@ -297,7 +297,7 @@ t.test('single arg', t => {
     npm.flatOptions.diff = ['bar']
     npm.flatOptions.prefix = path
 
-    const diff = requireInject('../../lib/diff.js', {
+    const Diff = requireInject('../../lib/diff.js', {
       ...mocks,
       pacote: {
         packument: (spec) => {
@@ -313,8 +313,9 @@ t.test('single arg', t => {
         t.equal(b, 'bar@1.8.10', 'should have possible semver range spec')
       },
     })
+    const diff = new Diff(npm)
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -359,7 +360,7 @@ t.test('single arg', t => {
     npm.flatOptions.prefix = resolve(path, 'project')
     npm.globalDir = resolve(path, 'globalDir/lib/node_modules')
 
-    const diff = requireInject('../../lib/diff.js', {
+    const Diff = requireInject('../../lib/diff.js', {
       ...mocks,
       pacote: {
         packument: (spec) => {
@@ -375,8 +376,9 @@ t.test('single arg', t => {
         t.equal(b, 'lorem@2.1.0', 'should have possible semver range spec')
       },
     })
+    const diff = new Diff(npm)
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -410,7 +412,7 @@ t.test('single arg', t => {
     npm.flatOptions.diff = ['bar@2.0.0']
     npm.flatOptions.prefix = path
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -445,7 +447,7 @@ t.test('single arg', t => {
       }),
     })
 
-    const diff = requireInject('../../lib/diff.js', {
+    const Diff = requireInject('../../lib/diff.js', {
       ...mocks,
       '../../lib/utils/read-local-package.js': async () => 'my-project',
       pacote: {
@@ -462,11 +464,12 @@ t.test('single arg', t => {
         t.equal(b, 'lorem@2.2.2', 'should have expected target spec')
       },
     })
+    const diff = new Diff(npm)
 
     npm.flatOptions.diff = ['lorem']
     npm.flatOptions.prefix = path
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -481,7 +484,7 @@ t.test('single arg', t => {
       }),
     })
 
-    const diff = requireInject('../../lib/diff.js', {
+    const Diff = requireInject('../../lib/diff.js', {
       ...mocks,
       '../../lib/utils/read-local-package.js': async () => 'my-project',
       '@npmcli/arborist': class {
@@ -494,11 +497,12 @@ t.test('single arg', t => {
         t.equal(b, `file:${path}`, 'should target current cwd')
       },
     })
+    const diff = new Diff(npm)
 
     npm.flatOptions.diff = ['lorem']
     npm.flatOptions.prefix = path
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -517,7 +521,7 @@ t.test('single arg', t => {
     npm.flatOptions.diff = ['bar']
     npm.flatOptions.prefix = path
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -535,7 +539,7 @@ t.test('single arg', t => {
 
     npm.flatOptions.diff = ['my-project']
     npm.flatOptions.prefix = path
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -553,7 +557,7 @@ t.test('single arg', t => {
 
     npm.flatOptions.diff = ['/path/to/other-dir']
     npm.flatOptions.prefix = path
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -564,7 +568,7 @@ t.test('single arg', t => {
 
     npm.flatOptions.diff = ['git+https://github.com/user/foo']
 
-    diff([], err => {
+    diff.exec([], err => {
       t.match(
         err,
         /Spec type not supported./,
@@ -588,7 +592,7 @@ t.test('first arg is a qualified spec', t => {
     }
 
     npm.flatOptions.diff = ['bar@1.0.0', 'bar@^2.0.0']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -622,7 +626,7 @@ t.test('first arg is a qualified spec', t => {
 
     npm.flatOptions.prefix = path
     npm.flatOptions.diff = ['bar@2.0.0', 'bar']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -638,7 +642,7 @@ t.test('first arg is a qualified spec', t => {
       t.equal(b, 'bar@2.0.0', 'should use name from first arg')
     }
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -653,7 +657,7 @@ t.test('first arg is a qualified spec', t => {
     }
 
     npm.flatOptions.diff = ['bar@1.0.0', 'bar-fork']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -691,7 +695,7 @@ t.test('first arg is a known dependency name', t => {
 
     npm.flatOptions.prefix = path
     npm.flatOptions.diff = ['bar', 'bar@2.0.0']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -731,7 +735,7 @@ t.test('first arg is a known dependency name', t => {
 
     npm.flatOptions.prefix = path
     npm.flatOptions.diff = ['bar', 'bar-fork']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -765,7 +769,7 @@ t.test('first arg is a known dependency name', t => {
 
     npm.flatOptions.prefix = path
     npm.flatOptions.diff = ['bar', '2.0.0']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -799,7 +803,7 @@ t.test('first arg is a known dependency name', t => {
 
     npm.flatOptions.prefix = path
     npm.flatOptions.diff = ['bar', 'bar-fork']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -819,7 +823,7 @@ t.test('first arg is a valid semver range', t => {
       t.equal(b, 'bar@2.0.0', 'should use expected spec')
     }
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -853,7 +857,7 @@ t.test('first arg is a valid semver range', t => {
 
     npm.flatOptions.prefix = path
     npm.flatOptions.diff = ['1.0.0', 'bar']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -869,7 +873,7 @@ t.test('first arg is a valid semver range', t => {
     }
 
     npm.flatOptions.diff = ['1.0.0', '2.0.0']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -883,7 +887,7 @@ t.test('first arg is a valid semver range', t => {
 
     npm.flatOptions.diff = ['1.0.0', '2.0.0']
     npm.flatOptions.prefix = path
-    diff([], err => {
+    diff.exec([], err => {
       t.match(
         err,
         /Needs to be run from a project dir in order to diff two versions./,
@@ -903,7 +907,7 @@ t.test('first arg is a valid semver range', t => {
     }
 
     npm.flatOptions.diff = ['1.0.0', 'bar']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -918,7 +922,7 @@ t.test('first arg is a valid semver range', t => {
       }),
     })
 
-    const diff = requireInject('../../lib/diff.js', {
+    const Diff = requireInject('../../lib/diff.js', {
       ...mocks,
       '../../lib/utils/read-local-package.js': async () => 'my-project',
       '@npmcli/arborist': class {
@@ -931,11 +935,12 @@ t.test('first arg is a valid semver range', t => {
         t.equal(b, 'lorem@2.0.0', 'should target expected spec')
       },
     })
+    const diff = new Diff(npm)
 
     npm.flatOptions.diff = ['1.0.0', 'lorem@2.0.0']
     npm.flatOptions.prefix = path
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -955,7 +960,7 @@ t.test('first arg is an unknown dependency name', t => {
     }
 
     npm.flatOptions.diff = ['bar', 'bar@2.0.0']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -989,7 +994,7 @@ t.test('first arg is an unknown dependency name', t => {
 
     npm.flatOptions.prefix = path
     npm.flatOptions.diff = ['bar-fork', 'bar']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -1004,7 +1009,7 @@ t.test('first arg is an unknown dependency name', t => {
     }
 
     npm.flatOptions.diff = ['bar', '^1.0.0']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -1019,7 +1024,7 @@ t.test('first arg is an unknown dependency name', t => {
     }
 
     npm.flatOptions.diff = ['bar', 'bar-fork']
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -1040,7 +1045,7 @@ t.test('first arg is an unknown dependency name', t => {
     npm.flatOptions.diff = ['bar', 'bar-fork']
     npm.flatOptions.prefix = path
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -1062,7 +1067,7 @@ t.test('various options', t => {
       }, 'should forward nameOnly=true option')
     }
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -1085,7 +1090,7 @@ t.test('various options', t => {
       }, 'should forward diffFiles values')
     }
 
-    diff(['./foo.js', './bar.js'], err => {
+    diff.exec(['./foo.js', './bar.js'], err => {
       if (err)
         throw err
     })
@@ -1109,7 +1114,7 @@ t.test('various options', t => {
     }
 
     npm.flatOptions.prefix = path
-    diff(['./foo.js', './bar.js'], err => {
+    diff.exec(['./foo.js', './bar.js'], err => {
       if (err)
         throw err
     })
@@ -1137,7 +1142,7 @@ t.test('various options', t => {
       }, 'should forward diff options')
     }
 
-    diff([], err => {
+    diff.exec([], err => {
       if (err)
         throw err
     })
@@ -1148,7 +1153,7 @@ t.test('various options', t => {
 
 t.test('too many args', t => {
   npm.flatOptions.diff = ['a', 'b', 'c']
-  diff([], err => {
+  diff.exec([], err => {
     t.match(
       err,
       /Can't use more than two --diff arguments./,