fmt: check formatting with --check (#1001)

Cargo.lock

@@ -231,6 +231,7 @@ dependencies = [
  "log",
  "pretty_assertions",
  "regex",
+ "similar",
  "snafu",
  "strum",
  "strum_macros",
@@ -463,6 +464,12 @@ version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "61b3909d758bb75c79f23d4736fac9433868679d3ad2ea7a61e3c25cfda9a088"
 
+[[package]]
+name = "similar"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2e24979f63a11545f5f2c60141afe249d4f19f84581ea2138065e400941d83d3"
+
 [[package]]
 name = "snafu"
 version = "0.6.10"

Cargo.toml

@@ -28,6 +28,7 @@ lexiclean = "0.0.1"
 libc = "0.2.0"
 log = "0.4.4"
 regex = "1.5.4"
+similar = "2.1.0"
 snafu = "0.6.0"
 strum_macros = "0.22.0"
 target = "2.0.0"

completions/just.bash

@@ -20,7 +20,7 @@ _just() {
 
     case "${cmd}" in
         just)
-            opts=" -q -u -v -e -l -h -V -f -d -c -s  --dry-run --highlight --no-dotenv --no-highlight --quiet --shell-command --clear-shell-args --unsorted --unstable --verbose --changelog --choose --dump --edit --evaluate --fmt --init --list --summary --variables --help --version --chooser --color --list-heading --list-prefix --justfile --set --shell --shell-arg --working-directory --command --completions --show --dotenv-filename --dotenv-path  <ARGUMENTS>... "
+            opts=" -q -u -v -e -l -h -V -f -d -c -s  --check --dry-run --highlight --no-dotenv --no-highlight --quiet --shell-command --clear-shell-args --unsorted --unstable --verbose --changelog --choose --dump --edit --evaluate --fmt --init --list --summary --variables --help --version --chooser --color --list-heading --list-prefix --justfile --set --shell --shell-arg --working-directory --command --completions --show --dotenv-filename --dotenv-path  <ARGUMENTS>... "
                 if [[ ${cur} == -* ]] ; then
                     COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                     return 0

completions/just.elvish

@@ -32,6 +32,7 @@ edit:completion:arg-completer[just] = [@words]{
             cand --show 'Show information about <RECIPE>'
             cand --dotenv-filename 'Search for environment file named <DOTENV-FILENAME> instead of `.env`'
             cand --dotenv-path 'Load environment file at <DOTENV-PATH> instead of searching for one'
+            cand --check 'Run `--fmt` in ''check'' mode. Exits with 0 if justfile is formatted correctly. Exits with 1 and prints a diff if formatting is required.'
             cand --dry-run 'Print what just would do without doing it'
             cand --highlight 'Highlight echoed recipe lines in bold'
             cand --no-dotenv 'Don''t load `.env` file'

completions/just.fish

@@ -23,6 +23,7 @@ complete -c just -n "__fish_use_subcommand" -l completions -d 'Print shell compl
 complete -c just -n "__fish_use_subcommand" -s s -l show -d 'Show information about <RECIPE>'
 complete -c just -n "__fish_use_subcommand" -l dotenv-filename -d 'Search for environment file named <DOTENV-FILENAME> instead of `.env`'
 complete -c just -n "__fish_use_subcommand" -l dotenv-path -d 'Load environment file at <DOTENV-PATH> instead of searching for one'
+complete -c just -n "__fish_use_subcommand" -l check -d 'Run `--fmt` in \'check\' mode. Exits with 0 if justfile is formatted correctly. Exits with 1 and prints a diff if formatting is required.'
 complete -c just -n "__fish_use_subcommand" -l dry-run -d 'Print what just would do without doing it'
 complete -c just -n "__fish_use_subcommand" -l highlight -d 'Highlight echoed recipe lines in bold'
 complete -c just -n "__fish_use_subcommand" -l no-dotenv -d 'Don\'t load `.env` file'

completions/just.powershell

@@ -37,6 +37,7 @@ Register-ArgumentCompleter -Native -CommandName 'just' -ScriptBlock {
             [CompletionResult]::new('--show', 'show', [CompletionResultType]::ParameterName, 'Show information about <RECIPE>')
             [CompletionResult]::new('--dotenv-filename', 'dotenv-filename', [CompletionResultType]::ParameterName, 'Search for environment file named <DOTENV-FILENAME> instead of `.env`')
             [CompletionResult]::new('--dotenv-path', 'dotenv-path', [CompletionResultType]::ParameterName, 'Load environment file at <DOTENV-PATH> instead of searching for one')
+            [CompletionResult]::new('--check', 'check', [CompletionResultType]::ParameterName, 'Run `--fmt` in ''check'' mode. Exits with 0 if justfile is formatted correctly. Exits with 1 and prints a diff if formatting is required.')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'Print what just would do without doing it')
             [CompletionResult]::new('--highlight', 'highlight', [CompletionResultType]::ParameterName, 'Highlight echoed recipe lines in bold')
             [CompletionResult]::new('--no-dotenv', 'no-dotenv', [CompletionResultType]::ParameterName, 'Don''t load `.env` file')

completions/just.zsh

@@ -33,6 +33,7 @@ _just() {
 '--show=[Show information about <RECIPE>]: :_just_commands' \
 '(--dotenv-path)--dotenv-filename=[Search for environment file named <DOTENV-FILENAME> instead of `.env`]' \
 '--dotenv-path=[Load environment file at <DOTENV-PATH> instead of searching for one]' \
+'--check[Run `--fmt` in '\''check'\'' mode. Exits with 0 if justfile is formatted correctly. Exits with 1 and prints a diff if formatting is required.]' \
 '(-q --quiet)--dry-run[Print what just would do without doing it]' \
 '--highlight[Highlight echoed recipe lines in bold]' \
 '--no-dotenv[Don'\''t load `.env` file]' \

src/config.rs

@@ -15,6 +15,7 @@ pub(crate) const DEFAULT_SHELL_ARG: &str = "-cu";
 #[derive(Debug, PartialEq)]
 pub(crate) struct Config {
   pub(crate) color: Color,
+  pub(crate) check: bool,
   pub(crate) dry_run: bool,
   pub(crate) highlight: bool,
   pub(crate) invocation_directory: PathBuf,
@@ -81,6 +82,7 @@ mod cmd {
 
 mod arg {
   pub(crate) const ARGUMENTS: &str = "ARGUMENTS";
+  pub(crate) const CHECK: &str = "CHECK";
   pub(crate) const CHOOSER: &str = "CHOOSER";
   pub(crate) const CLEAR_SHELL_ARGS: &str = "CLEAR-SHELL-ARGS";
   pub(crate) const COLOR: &str = "COLOR";
@@ -116,6 +118,12 @@ impl Config {
       .version_message("Print version information")
       .setting(AppSettings::ColoredHelp)
       .setting(AppSettings::TrailingVarArg)
+      .arg(
+        Arg::with_name(arg::CHECK)
+          .long("check")
+          .requires(cmd::FORMAT)
+          .help("Run `--fmt` in 'check' mode. Exits with 0 if justfile is formatted correctly. Exits with 1 and prints a diff if formatting is required."),
+      )
       .arg(
         Arg::with_name(arg::CHOOSER)
           .long("chooser")
@@ -532,6 +540,7 @@ impl Config {
       || matches.occurrences_of(arg::SHELL_ARG) > 0;
 
     Ok(Self {
+      check: matches.is_present(arg::CHECK),
       dry_run: matches.is_present(arg::DRY_RUN),
       highlight: !matches.is_present(arg::NO_HIGHLIGHT),
       shell: matches.value_of(arg::SHELL).unwrap().to_owned(),
@@ -594,6 +603,9 @@ USAGE:
 
 FLAGS:
         --changelog           Print changelog
+        --check               Run `--fmt` in 'check' mode. Exits with 0 if
+                              justfile is formatted correctly. Exits with 1 and
+                              prints a diff if formatting is required.
         --choose              Select one or more recipes to run using a binary.
                               If `--chooser` is not passed the chooser defaults
                               to the value of $JUST_CHOOSER, falling back to

src/error.rs

@@ -75,6 +75,7 @@ pub(crate) enum Error<'src> {
     variable: String,
     suggestion: Option<Suggestion<'src>>,
   },
+  FormatCheckFoundDiff,
   FunctionCall {
     function: Name<'src>,
     message: String,
@@ -458,6 +459,9 @@ impl<'src> ColorDisplay for Error<'src> {
           write!(f, "\n{}", suggestion)?;
         }
       }
+      FormatCheckFoundDiff => {
+        write!(f, "Formatted justfile differs from original.")?;
+      }
       FunctionCall { function, message } => {
         write!(
           f,

src/subcommand.rs

@@ -77,7 +77,7 @@ impl Subcommand {
         justfile.run(config, &search, overrides, &[])?
       }
       Dump => Self::dump(ast),
-      Format => Self::format(config, ast, &search)?,
+      Format => Self::format(config, ast, &src, &search)?,
       List => Self::list(config, justfile),
       Run {
         arguments,
@@ -255,11 +255,22 @@ impl Subcommand {
     Ok(())
   }
 
-  fn format(config: &Config, ast: Ast, search: &Search) -> Result<(), Error<'static>> {
+  fn format(config: &Config, ast: Ast, src: &str, search: &Search) -> Result<(), Error<'static>> {
     config.require_unstable("The `--fmt` command is currently unstable.")?;
 
-    if let Err(io_error) =
+    let src_formatted = ast.to_string();
-      File::create(&search.justfile).and_then(|mut file| write!(file, "{}", ast))
+    if config.check {
+      if src == src_formatted {
+        Ok(())
+      } else {
+        print!(
+          "{}",
+          similar::udiff::unified_diff(similar::Algorithm::Patience, &src, &src_formatted, 2, None)
+        );
+        Err(Error::FormatCheckFoundDiff)
+      }
+    } else if let Err(io_error) =
+      File::create(&search.justfile).and_then(|mut file| file.write_all(&src_formatted.as_bytes()))
     {
       Err(Error::WriteJustfile {
         justfile: search.justfile.clone(),

tests/fmt.rs

@@ -11,6 +11,51 @@ test! {
   status: EXIT_FAILURE,
 }
 
+test! {
+  name: check_without_fmt,
+  justfile: "",
+  args: ("--check"),
+  stderr_regex: "error: The following required arguments were not provided:
+    --fmt
+(.|\\n)+",
+  status: EXIT_FAILURE,
+}
+
+test! {
+  name: dry_run_ok,
+  justfile: r#"
+# comment   with   spaces
+
+export x := `backtick
+with
+lines`
+
+recipe: deps
+    echo "$x"
+
+deps:
+    echo {{ x }}
+    echo '$x'
+"#,
+  args: ("--unstable", "--fmt", "--check"),
+  status: EXIT_SUCCESS,
+}
+
+test! {
+  name: dry_run_found_diff,
+  justfile: "x:=``\n",
+  args: ("--unstable", "--fmt", "--check"),
+  stdout: "
+  @@ -1 +1 @@
+  -x:=``
+  +x := ``
+  ",
+  stderr: "
+    error: Formatted justfile differs from original.
+  ",
+  status: EXIT_FAILURE,
+}
+
 #[test]
 fn unstable_passed() {
   let tmp = tempdir();