feat(cmd): do some heuristic guesswork on default command names (#23)

Fixes: #12

Author: zkat

README.md

@@ -16,6 +16,8 @@ Executes `<command>` either from a local `node_modules/.bin`, or from a central
 
 By default, `npx` will check whether `<command>` exists in `$PATH`, or in the local project binaries, and execute that. If `<command>` is not found, it will be installed prior to execution.
 
+Unless a `--package` option is specified, `npx` will try to guess the name of the binary to invoke depending on the specifier provided. All package specifiers understood by `npm` may be used with `npx`, including git specifiers, remote tarballs, local directories, or scoped packages.
+
 An optional `@version` may be appended to specify the package version required, which defaults to `latest` only if `<command>` is not in the path. If the command is already present and no explicit version specifier was requested, the existing command will be used.
 
 If a version specifier is included, or if `--package` is used, npx will ignore the version of the package in the current path, if it exists. This can also be forced with the `--ignore-existing` flag.
@@ -42,7 +44,7 @@ If a version specifier is included, or if `--package` is used, npx will ignore t
 
 ```
 $ npm i -D webpack
-$ npx webpack -- ...
+$ npx webpack ...
 ```
 
 ### One-off invocation without local installation
@@ -54,6 +56,15 @@ $ cat package.json
 ...webpack not in "devDependencies"...
 ```
 
+### Invoking a command from a github repository
+
+```
+$ npx github:piuccio/cowsay
+...or...
+$ npx git+ssh://my.hosted.git:cowsay.git#semver:^1
+...etc...
+```
+
 ### Execute a full shell command using one npx call
 
 ```

parse-args.js

@@ -1,6 +1,7 @@
 'use strict'
 
 const npa = require('npm-package-arg')
+const path = require('path')
 const yargs = require('yargs')
 
 const usage = `$0 [--package|-p <package>] [--cache <path>] [--userconfig <path>] [-c <string>] [--shell <string>] [--shell-auto-fallback [<shell>]] [--ignore-existing] [--version|-v] [--] <command>[@version] [command-arg]...`
@@ -71,7 +72,7 @@ function parseArgs () {
     const parsedCmd = npa(process.argv[cmdIndex])
     parsed.command = parsed.package
     ? process.argv[cmdIndex]
-    : parsedCmd.name
+    : guessCmdName(parsedCmd)
     parsed.cmdOpts = process.argv.slice(cmdIndex + 1)
     parsed.packageRequested = !!parsed.package
     parsed.cmdHadVersion = parsedCmd.name !== parsedCmd.raw
@@ -85,7 +86,7 @@ function parseArgs () {
       const parsedCmd = npa(splitCmd[0])
       parsed.command = parsed.package
       ? splitCmd[0]
-      : parsedCmd.name
+      : guessCmdName(parsedCmd)
       parsed.cmdOpts = splitCmd.slice(1)
       parsed.packageRequested = !!parsed.package
       parsed.cmdHadVersion = parsedCmd.name !== parsedCmd.raw
@@ -96,11 +97,39 @@ function parseArgs () {
       const parsedCmd = npa(splitCmd[0])
       parsed.command = parsed.package
       ? splitCmd[0]
-      : parsedCmd.name
+      : guessCmdName(parsedCmd)
       parsed.cmdOpts = splitCmd.slice(1)
       parsed.packageRequested = !!parsed.package
       parsed.cmdHadVersion = parsedCmd.name !== parsedCmd.raw
     }
     return parsed
   }
 }
+
+module.exports._guessCmdName = guessCmdName
+function guessCmdName (spec) {
+  if (typeof spec === 'string') { spec = npa(spec) }
+  if (spec.scope) {
+    return spec.name.slice(spec.scope.length + 1)
+  } else if (spec.registry) {
+    return spec.name
+  } else if (spec.hosted && spec.hosted.project) {
+    return spec.hosted.project
+  } else if (spec.type === 'git') {
+    const match = spec.fetchSpec.match(/([a-z0-9-]+)(?:\.git)?$/i)
+    if (match && match[1]) {
+      return match[1]
+    }
+  } else if (spec.type === 'directory') {
+    return path.basename(spec.fetchSpec)
+  } else if (spec.type === 'file' || spec.type === 'remote') {
+    let ext = path.extname(spec.fetchSpec)
+    if (ext === '.gz') {
+      ext = path.extname(path.basename(spec.fetchSpec, ext)) + ext
+    }
+    return path.basename(spec.fetchSpec, ext).replace(/-\d+\.\d+\.\d+(?:-[a-z0-9.\-+]+)?$/i, '')
+  }
+
+  console.error(`Unable to guess a binary name from ${spec.raw}. Please use --package.`)
+  return null
+}

test/guess-command-name.js

@@ -0,0 +1,59 @@
+'use strict'
+
+const test = require('tap').test
+
+const guessCmdName = require('../parse-args.js')._guessCmdName
+
+test('guesses unscoped registry binaries', t => {
+  t.equal(guessCmdName('foo'), 'foo')
+  t.done()
+})
+
+test('guesses scoped registry binaries', t => {
+  t.equal(guessCmdName('@user/foo'), 'foo')
+  t.done()
+})
+
+test('guesses hosted git binaries', t => {
+  t.equal(guessCmdName('user/foo'), 'foo')
+  t.equal(guessCmdName('git+ssh://git@github.com:user/foo.git#semver:^1'), 'foo')
+  t.done()
+})
+
+test('guesses git binaries', t => {
+  t.equal(guessCmdName('git+ssh://myhost.com:user/foo.git#semver:^1'), 'foo')
+  t.equal(guessCmdName('git://myhost.com:foo'), 'foo')
+  t.done()
+})
+
+test('guesses local directory binaries', t => {
+  t.equal(guessCmdName('./foo'), 'foo')
+  t.equal(guessCmdName('./dir/foo'), 'foo')
+  t.equal(guessCmdName('../../../dir/foo'), 'foo')
+  t.equal(guessCmdName('C:\\Program Files\\node\\foo'), 'foo')
+  t.done()
+})
+
+test('guesses remote tarballs', t => {
+  t.equal(guessCmdName('https://registry.npmjs.org/foo/-/foo-1.2.3.tgz'), 'foo')
+  t.equal(guessCmdName('http://registry.npmjs.org/foo/-/foo-1.2.3-prerelease.5+buildnum.tgz'), 'foo')
+  t.equal(guessCmdName('https://github.com/tarball/blah/foo.tar.gz'), 'foo')
+  t.done()
+})
+
+test('guesses local tarballs', t => {
+  t.equal(guessCmdName('./foo-1.2.3.tgz'), 'foo')
+  t.equal(guessCmdName('./dir/foo.tar.gz'), 'foo')
+  t.equal(guessCmdName('C:\\Program Files\\dir/foo-bar.tar.gz'), 'foo-bar')
+  t.done()
+})
+
+test('warns when something could not be guessed', t => {
+  const oldErr = console.error
+  console.error = str => {
+    t.match(str, /Unable to guess a binary name/)
+  }
+  guessCmdName({})
+  console.error = oldErr
+  t.done()
+})