refactor!: replace anyhow with thiserror

BREAKING CHANGE: Library functions no longer expose `anyhow::Result`,
instead exposing `std::error::Error` via thiserror.

Author: EricCrosson

Cargo.lock

@@ -36,15 +36,14 @@ name = "typescript_tools"
 path = "src/lib.rs"
 
 [dependencies]
-anyhow = "=1.0.70"
 askama = "=0.12.0"
 clap = { version = "=4.2.1", features = ["cargo", "derive"] }
 globwalk = "=0.8.1"
-indoc = "=2.0.1"
 pariter = "=0.5.1"
 pathdiff = "=0.2.1"
 serde = { version = "=1.0.159", features = ["derive"] }
 serde_json = { version = "=1.0.95", features = ["preserve_order"] }
+thiserror = "=1.0.40"
 
 [dev-dependencies]
 semantic-release-rust = "1.0.0-alpha.8"

Cargo.toml

@@ -4,9 +4,10 @@ use std::{
     path::{Path, PathBuf},
 };
 
-use anyhow::Result;
 use serde::Serialize;
 
+use crate::error::Error;
+
 // REFACTOR: most of this impl is the same across all types
 /// Configuration file for some component of the monorepo.
 pub trait ConfigurationFile: Sized {
@@ -17,7 +18,7 @@ pub trait ConfigurationFile: Sized {
 
     /// Create an instance of this configuration file by reading
     /// the specified file from this directory on disk.
-    fn from_directory(monorepo_root: &Path, directory: &Path) -> Result<Self>;
+    fn from_directory(monorepo_root: &Path, directory: &Path) -> Result<Self, Error>;
 
     /// Relative path to directory containing this configuration file,
     /// from monorepo root.
@@ -31,11 +32,26 @@ pub trait ConfigurationFile: Sized {
     fn write(
         monorepo_root: &Path,
         configuration_file: impl ConfigurationFile,
-    ) -> std::io::Result<()> {
-        let file = File::create(monorepo_root.join(configuration_file.path()))?;
+    ) -> Result<(), Error> {
+        let filename = monorepo_root.join(configuration_file.path());
+        let file = File::create(filename.clone()).map_err(|source| Error::WriteFile {
+            filename: filename.clone(),
+            source,
+        })?;
         let mut writer = BufWriter::new(file);
-        serde_json::to_writer_pretty(&mut writer, configuration_file.contents())?;
-        writer.write_all(b"\n")?;
-        writer.flush()
+        serde_json::to_writer_pretty(&mut writer, configuration_file.contents()).map_err(
+            |source| Error::SerializeJSON {
+                filename: filename.clone(),
+                source,
+            },
+        )?;
+        writer
+            .write_all(b"\n")
+            .and_then(|_| writer.flush())
+            .map_err(|source| Error::WriteFile {
+                filename: filename.clone(),
+                source,
+            })?;
+        Ok(())
     }
 }

src/configuration_file.rs

@@ -0,0 +1,40 @@
+use std::path::PathBuf;
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("Unable to read file {filename:?}: {source}")]
+    ReadFile {
+        filename: PathBuf,
+        source: std::io::Error,
+    },
+
+    #[error("Unable to parse JSON from file {filename:?}: {source}")]
+    ParseJSON {
+        filename: PathBuf,
+        source: serde_json::Error,
+    },
+
+    #[error("Unable to serialize JSON into {filename:?}: {source}")]
+    SerializeJSON {
+        filename: PathBuf,
+        source: serde_json::Error,
+    },
+
+    #[error("Unable to write file {filename:?}: {source}")]
+    WriteFile {
+        filename: PathBuf,
+        source: std::io::Error,
+    },
+
+    #[error("Project references are out-of-date")]
+    ProjectReferencesOutOfDate,
+
+    #[error("Unexpected dependency versions for internal packages")]
+    UnexpectedInternalDependencyVersion,
+
+    #[error("Unable to write to buffer")]
+    BufferWrite(#[source] std::io::Error),
+
+    #[error("Unable to convert value into JSON")]
+    ToJSON(#[source] serde_json::Error),
+}

src/error.rs

@@ -1,19 +1,23 @@
-use anyhow::Context;
 use std::fs;
 use std::path::Path;
 
-use anyhow::Result;
-
 use serde::Deserialize;
 
-pub(crate) fn read_json_from_file<T>(filename: &Path) -> Result<T>
+use crate::error::Error;
+
+pub(crate) fn read_json_from_file<T>(filename: &Path) -> Result<T, Error>
 where
     for<'de> T: Deserialize<'de>,
 {
     // Reading a file into a string before invoking Serde is faster than
     // invoking Serde from a BufReader, see
     // https://github.com/serde-rs/json/issues/160
-    let string = fs::read_to_string(filename)?;
-    serde_json::from_str(&string)
-        .with_context(|| format!("Unable to parse JSON from file {:?}", filename))
+    let string = fs::read_to_string(filename).map_err(|source| Error::ReadFile {
+        filename: filename.to_owned(),
+        source,
+    })?;
+    serde_json::from_str(&string).map_err(|source| Error::ParseJSON {
+        filename: filename.to_owned(),
+        source,
+    })
 }

src/io.rs

@@ -4,6 +4,7 @@ mod io;
 mod typescript_config;
 
 pub mod configuration_file;
+pub mod error;
 pub mod link;
 pub mod lint;
 pub mod make_depend;

src/lib.rs

@@ -1,11 +1,10 @@
 use std::collections::HashMap;
 use std::path::PathBuf;
 
-use anyhow::{bail, Result};
-
 use pathdiff::diff_paths;
 
 use crate::configuration_file::ConfigurationFile;
+use crate::error::Error;
 use crate::monorepo_manifest::MonorepoManifest;
 use crate::opts;
 use crate::package_manifest::PackageManifest;
@@ -47,7 +46,10 @@ fn create_project_references(mut children: Vec<String>) -> Vec<TypescriptProject
 
 // Create a tsconfig.json file in each parent directory to an internal package.
 // This permits us to compile the monorepo from the top down.
-fn link_children_packages(opts: &opts::Link, lerna_manifest: &MonorepoManifest) -> Result<bool> {
+fn link_children_packages(
+    opts: &opts::Link,
+    lerna_manifest: &MonorepoManifest,
+) -> Result<bool, Error> {
     let mut is_exit_success = true;
 
     lerna_manifest
@@ -56,7 +58,7 @@ fn link_children_packages(opts: &opts::Link, lerna_manifest: &MonorepoManifest)
         .fold(HashMap::new(), key_children_by_parent)
         .into_iter()
         // DISCUSS: trying all of this in parallel
-        .try_for_each(|(directory, children)| -> Result<()> {
+        .try_for_each(|(directory, children)| -> Result<(), Error> {
             let desired_project_references = create_project_references(children);
             let mut tsconfig =
                 TypescriptParentProjectReference::from_directory(&opts.root, &directory)?;
@@ -67,7 +69,11 @@ fn link_children_packages(opts: &opts::Link, lerna_manifest: &MonorepoManifest)
             }
             if opts.check_only {
                 is_exit_success = false;
-                let serialized = serde_json::to_string_pretty(&desired_project_references)?;
+                let serialized = serde_json::to_string_pretty(&desired_project_references)
+                    .map_err(|source| Error::SerializeJSON {
+                        filename: tsconfig.path(),
+                        source,
+                    })?;
                 println!(
                     "File has out-of-date project references: {:?}, expecting:",
                     tsconfig.path()
@@ -85,7 +91,10 @@ fn link_children_packages(opts: &opts::Link, lerna_manifest: &MonorepoManifest)
     Ok(is_exit_success)
 }
 
-fn link_package_dependencies(opts: &opts::Link, lerna_manifest: &MonorepoManifest) -> Result<bool> {
+fn link_package_dependencies(
+    opts: &opts::Link,
+    lerna_manifest: &MonorepoManifest,
+) -> Result<bool, Error> {
     // NOTE: this line calls LernaManifest::get_internal_package_manifests (the sloweset function) twice
     let package_manifest_by_package_name = lerna_manifest.package_manifests_by_package_name()?;
 
@@ -137,23 +146,29 @@ fn link_package_dependencies(opts: &opts::Link, lerna_manifest: &MonorepoManifes
             // Update the current tsconfig with the desired references
             tsconfig.contents.insert(
                 String::from("references"),
-                serde_json::to_value(desired_project_references)?,
+                serde_json::to_value(desired_project_references).map_err(Error::ToJSON)?,
             );
 
             Ok(Some(tsconfig))
         })
-        .collect::<Result<Vec<Option<TypescriptConfig>>>>()?;
+        .collect::<Result<Vec<Option<TypescriptConfig>>, Error>>()?;
 
     // take action on the computed diffs
     let mut is_exit_success = true;
 
     tsconfig_diffs
         .into_iter()
         .flatten()
-        .map(|tsconfig| -> Result<()> {
+        .map(|tsconfig| -> Result<(), Error> {
             if opts.check_only {
                 is_exit_success = false;
-                let serialized = serde_json::to_string_pretty(&tsconfig.contents)?;
+                let serialized =
+                    serde_json::to_string_pretty(&tsconfig.contents).map_err(|source| {
+                        Error::SerializeJSON {
+                            filename: tsconfig.path(),
+                            source,
+                        }
+                    })?;
                 println!(
                     "File has out-of-date project references: {:?}, expecting:",
                     tsconfig.path()
@@ -170,7 +185,7 @@ fn link_package_dependencies(opts: &opts::Link, lerna_manifest: &MonorepoManifes
     Ok(is_exit_success)
 }
 
-pub fn link_typescript_project_references(opts: opts::Link) -> Result<()> {
+pub fn link_typescript_project_references(opts: opts::Link) -> Result<(), Error> {
     let lerna_manifest =
         MonorepoManifest::from_directory(&opts.root).expect("Unable to read monorepo manifest");
 
@@ -181,7 +196,7 @@ pub fn link_typescript_project_references(opts: opts::Link) -> Result<()> {
         .expect("Unable to link internal package dependencies");
 
     if opts.check_only && !(is_children_link_success && is_dependencies_link_success) {
-        bail!("Found out-of-date project references")
+        return Err(Error::ProjectReferencesOutOfDate);
     }
 
     // TODO(7): create `tsconfig.settings.json` files

src/link.rs

@@ -1,13 +1,11 @@
 use std::collections::HashMap;
 
-use anyhow::{ensure, Result};
-
-use crate::opts;
-
 use crate::configuration_file::ConfigurationFile;
+use crate::error::Error;
 use crate::monorepo_manifest::MonorepoManifest;
+use crate::opts;
 
-pub fn handle_subcommand(opts: opts::Lint) -> Result<()> {
+pub fn handle_subcommand(opts: opts::Lint) -> Result<(), Error> {
     match opts.subcommand {
         opts::ClapLintSubCommand::DependencyVersion(args) => lint_dependency_version(&args),
     }
@@ -27,7 +25,7 @@ fn most_common_dependency_version(
         .map(|(k, _v)| k.to_owned())
 }
 
-fn lint_dependency_version(opts: &opts::DependencyVersion) -> Result<()> {
+fn lint_dependency_version(opts: &opts::DependencyVersion) -> Result<(), Error> {
     let opts::DependencyVersion { root, dependencies } = opts;
 
     let lerna_manifest = MonorepoManifest::from_directory(root)?;
@@ -88,6 +86,8 @@ fn lint_dependency_version(opts: &opts::DependencyVersion) -> Result<()> {
         is_exit_success = false;
     }
 
-    ensure!(is_exit_success, "Found unexpected dependency versions");
+    if !is_exit_success {
+        return Err(Error::UnexpectedInternalDependencyVersion);
+    }
     Ok(())
 }

src/lint.rs

@@ -1,19 +1,17 @@
 #![forbid(unsafe_code)]
 
-use anyhow::Result;
-
 use clap::Parser;
 
 use typescript_tools::{link, lint, make_depend, opts, pin, query};
 
-fn main() -> Result<()> {
+fn main() -> Result<(), Box<dyn std::error::Error>> {
     let opts = opts::Opts::parse();
 
-    match opts.subcommand {
+    Ok(match opts.subcommand {
         opts::ClapSubCommand::Link(args) => link::link_typescript_project_references(args),
         opts::ClapSubCommand::Pin(args) => pin::pin_version_numbers_in_internal_packages(args),
         opts::ClapSubCommand::MakeDepend(args) => make_depend::make_dependency_makefile(args),
         opts::ClapSubCommand::Query(args) => query::handle_subcommand(args),
         opts::ClapSubCommand::Lint(args) => lint::handle_subcommand(args),
-    }
+    }?)
 }