✨ feat: support reading commit message from a file

src/args.rs

@@ -24,6 +24,14 @@ pub struct Opt {
     )]
     pub init: Option<InitOption>,
 
+    #[arg(
+        long = "file",
+        value_name = "FILE",
+        help = "Read commit message from file",
+        conflicts_with = "commit_message"
+    )]
+    pub commit_file: Option<String>,
+
     /// Outputs enabled rules' description as bash comments for the prepare-commit-msg hook.
     #[arg(long, num_args = 0, hide = true)]
     pub prepare_commit_message: bool,

src/errors.rs

@@ -5,6 +5,9 @@ pub enum SumiError {
     #[error("{details}")]
     GeneralError { details: String },
 
+    #[error("Failed to read commit message from file '{path}': {error}")]
+    CommitFileError { path: String, error: String },
+
     #[error("{lines_with_errors} out of {total_lines} {line_or_lines} failed linting. See the errors above")]
     SplitLinesErrors {
         lines_with_errors: usize,

src/lib.rs

@@ -47,7 +47,7 @@ pub fn run() -> Result<(), SumiError> {
         return Err(SumiError::NoRulesEnabled);
     }
 
-    let commit_message = get_commit_from_arg_or_stdin(args.commit_message)?;
+    let commit_message = get_commit_from_arg_or_stdin(args.commit_message, args.commit_file)?;
 
     let lint_result = if config.split_lines {
         run_lint_on_each_line(&commit_message, &config)
@@ -85,14 +85,25 @@ fn init_logger_from_config(config: &Config) {
         .init();
 }
 
-fn get_commit_from_arg_or_stdin(commit: Option<String>) -> Result<String, SumiError> {
-    if let Some(commit) = commit {
-        Ok(commit)
-    } else {
-        get_commit_from_stdin()
+fn get_commit_from_arg_or_stdin(
+    commit: Option<String>,
+    commit_file: Option<String>,
+) -> Result<String, SumiError> {
+    match (commit, commit_file) {
+        (Some(message), _) => Ok(message),
+        (None, Some(path)) => get_commit_from_file(&path),
+        (None, None) => get_commit_from_stdin(),
     }
 }
 
+fn get_commit_from_file(path: &str) -> Result<String, SumiError> {
+    std::fs::read_to_string(path)
+        .map(|content| content.trim().to_string())
+        .map_err(|e| SumiError::GeneralError {
+            details: format!("Could not read commit message from '{}': {}", path, e),
+        })
+}
+
 fn get_commit_from_stdin() -> Result<String, SumiError> {
     let mut buffer = String::new();
     io::stdin().read_to_string(&mut buffer)?;

tests/lint/mod.rs

@@ -3,6 +3,7 @@ mod test_commit_changes;
 mod test_config;
 mod test_conventional_commits;
 mod test_display;
+mod test_file_input;
 mod test_gitmoji;
 mod test_single_rule;
 

tests/lint/test_file_input.rs

@@ -0,0 +1,84 @@
+use crate::run_isolated_git_sumi;
+use predicates::str::contains;
+use tempfile::tempdir;
+
+#[test]
+fn success_read_from_file() {
+    let dir = tempdir().unwrap();
+    let file_path = dir.path().join("commit-msg.txt");
+    std::fs::write(&file_path, "feat: add new feature").unwrap();
+    let mut cmd = run_isolated_git_sumi("");
+    cmd.arg("--file")
+        .arg(file_path)
+        .arg("-C")
+        .assert()
+        .success();
+}
+
+#[test]
+fn error_nonexistent_file() {
+    let mut cmd = run_isolated_git_sumi("");
+    cmd.arg("--file")
+        .arg("nonexistent-file.txt")
+        .arg("-C")
+        .assert()
+        .failure()
+        .stderr(contains(
+            "Could not read commit message from 'nonexistent-file.txt'",
+        ));
+}
+
+#[test]
+fn error_empty_file() {
+    let dir = tempdir().unwrap();
+    let file_path = dir.path().join("empty.txt");
+    std::fs::write(&file_path, "").unwrap();
+    let mut cmd = run_isolated_git_sumi("");
+    cmd.arg("--file")
+        .arg(file_path)
+        .arg("-C")
+        .assert()
+        .failure()
+        .stderr(contains("Header must not be empty"));
+}
+
+#[test]
+fn error_conflict_file_and_message() {
+    let dir = tempdir().unwrap();
+    let file_path = dir.path().join("commit.txt");
+    std::fs::write(&file_path, "feat: test").unwrap();
+
+    let mut cmd = run_isolated_git_sumi("");
+    cmd.arg("--file")
+        .arg(file_path)
+        .arg("direct message")
+        .assert()
+        .failure()
+        .stderr(contains("cannot be used with"));
+}
+
+#[test]
+fn success_file_with_comments() {
+    let dir = tempdir().unwrap();
+    let file_path = dir.path().join("commit-with-comments.txt");
+    std::fs::write(&file_path, "feat: add feature\n# This is a comment\n").unwrap();
+    let mut cmd = run_isolated_git_sumi("");
+    cmd.arg("--file")
+        .arg(file_path)
+        .arg("-C")
+        .assert()
+        .success();
+}
+
+#[test]
+fn success_file_with_multiline() {
+    let dir = tempdir().unwrap();
+    let file_path = dir.path().join("multiline.txt");
+    std::fs::write(&file_path, "feat: add feature\n\nDetailed description").unwrap();
+    let mut cmd = run_isolated_git_sumi("");
+    cmd.arg("--file")
+        .arg(file_path)
+        .arg("-C")
+        .assert()
+        .success();
+}

website/docs/usage.md

@@ -38,6 +38,8 @@ git-sumi [OPTIONS] [--] [COMMIT_MESSAGE]
         Path to a TOML configuration file [env: GIT_SUMI_CONFIG=]
 -f, --format <FORMAT>
         Sets display format: cli, json, table, toml [env: GIT_SUMI_FORMAT=]
+    --file <FILE>
+        Read commit message from file
 ```
 
 ### Rules