jj_cz/commit/types/

message.rs

use super::{Body, BreakingChange, CommitType, Description, Footer, References, Scope};
use thiserror::Error;

/// Errors that can occur when creating a ConventionalCommit
#[derive(Debug, Clone, PartialEq, Eq, Error)]
pub enum CommitMessageError {
    /// The complete first line exceeds the maximum allowed length
    #[error("first line too long: {actual} characters (max {max})")]
    FirstLineTooLong { actual: usize, max: usize },

    /// The formatted message is not parseable as a conventional commit
    ///
    /// This should never occur in normal use - it indicates a bug in the
    /// formatting logic.
    #[error("output failed git-conventional validation: {reason}")]
    InvalidConventionalFormat { reason: String },
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ConventionalCommit {
    commit_type: CommitType,
    scope: Scope,
    description: Description,
    breaking_change: BreakingChange,
    body: Body,
    references: References,
}

impl ConventionalCommit {
    /// Maximum allowed length for the complete first line (type + scope + description)
    pub const FIRST_LINE_MAX_LENGTH: usize = 72;

    /// Create a new conventional commit message
    ///
    /// # Arguments
    /// All arguments are pre-validated types, but the combined first line
    /// length is validated here (max 72 characters).
    ///
    /// # Errors
    /// Returns `CommitMessageError::FirstLineTooLong` if the formatted first
    /// line exceeds 72 characters.
    pub fn new(
        commit_type: CommitType,
        scope: Scope,
        description: Description,
        breaking_change: BreakingChange,
        body: Body,
        references: References,
    ) -> Result<Self, CommitMessageError> {
        let commit = Self {
            commit_type,
            scope,
            description,
            breaking_change,
            body,
            references,
        };
        let len = commit.first_line_len();
        if len > Self::FIRST_LINE_MAX_LENGTH {
            return Err(CommitMessageError::FirstLineTooLong {
                actual: len,
                max: Self::FIRST_LINE_MAX_LENGTH,
            });
        }
        let formatted = commit.format();
        git_conventional::Commit::parse(&formatted).map_err(|e| {
            CommitMessageError::InvalidConventionalFormat {
                reason: e.to_string(),
            }
        })?;
        Ok(commit)
    }

    /// Calculate the length of the formatted first line
    ///
    /// Formula:
    /// - `len(type)` + `len(scope)` + `len(breaking_change)` + 2 + `len(description)`
    ///   (the 2 accounts for colon and space: ": ")
    pub fn first_line_len(&self) -> usize {
        self.commit_type.len()
            + self.scope.header_segment_len()
            + if self.breaking_change.is_absent() { 0 } else { 1 }
            + 2 // ": "
            + self.description.len()
    }

    /// Format the complete commit message
    ///
    /// Returns `type(scope): description` if scope is non-empty, or
    /// `type: description` if scope is empty
    pub fn format(&self) -> String {
        Self::format_preview(
            self.commit_type,
            &self.scope,
            &self.description,
            &self.breaking_change,
            &self.body,
            &self.references,
        )
    }

    /// Format a preview of the commit message without creating a validated instance
    ///
    /// This is useful for showing what the message would look like before validation
    /// Returns `type(scope): description` if scope is non-empty, or
    /// `type: description` if scope is empty
    pub fn format_preview(
        commit_type: CommitType,
        scope: &Scope,
        description: &Description,
        breaking_change: &BreakingChange,
        body: &Body,
        references: &References,
    ) -> String {
        let scope = scope.header_segment();
        let breaking_change_header = breaking_change.header_segment();
        let breaking_change_footer = breaking_change.as_footer();
        let refs_footer = references.as_footer();
        format!(
            r#"{commit_type}{scope}{breaking_change_header}: {description}
{}
{breaking_change_footer}{refs_footer}"#,
            body.format()
        )
        .trim()
        .to_string()
    }
}

impl std::fmt::Display for ConventionalCommit {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.format())
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// Helper to create a valid Scope for testing
    fn test_scope(value: &str) -> Scope {
        Scope::parse(value).expect("test scope should be valid")
    }

    /// Helper to create a valid Description for testing
    fn test_description(value: &str) -> Description {
        Description::parse(value).expect("test description should be valid")
    }

    /// Helper to create a valid ConventionalCommit for testing
    fn test_commit(
        commit_type: CommitType,
        scope: Scope,
        description: Description,
        breaking_change: BreakingChange,
    ) -> ConventionalCommit {
        ConventionalCommit::new(
            commit_type,
            scope,
            description,
            breaking_change,
            Body::default(),
            References::default(),
        )
        .expect("test commit should have valid line length")
    }

    /// Test that ConventionalCommit::new() creates a valid commit with all fields
    #[test]
    fn new_creates_commit_with_all_fields() {
        let commit = test_commit(
            CommitType::Feat,
            test_scope("cli"),
            test_description("add new feature"),
            BreakingChange::No,
        );
        assert_eq!(commit.commit_type, CommitType::Feat);
        assert_eq!(commit.scope.as_str(), "cli");
        assert_eq!(commit.description.as_str(), "add new feature");
    }

    /// Test that ConventionalCommit::new() works with empty scope
    #[test]
    fn new_creates_commit_with_empty_scope() {
        let commit = test_commit(
            CommitType::Fix,
            Scope::empty(),
            test_description("fix critical bug"),
            BreakingChange::No,
        );
        assert_eq!(commit.commit_type, CommitType::Fix);
        assert!(commit.scope.is_empty());
        assert_eq!(commit.description.as_str(), "fix critical bug");
    }

    /// Test that format() produces "type(scope): description" when scope is non-empty
    #[test]
    fn format_with_scope_produces_correct_output() {
        let commit = test_commit(
            CommitType::Feat,
            test_scope("auth"),
            test_description("add login"),
            BreakingChange::No,
        );
        assert_eq!(commit.format(), "feat(auth): add login");
    }

    /// Test format with different scope values
    #[test]
    fn format_with_various_scopes() {
        // Hyphenated scope
        let commit1 = test_commit(
            CommitType::Fix,
            test_scope("user-auth"),
            test_description("fix token refresh"),
            BreakingChange::No,
        );
        assert_eq!(commit1.format(), "fix(user-auth): fix token refresh");

        // Underscored scope
        let commit2 = test_commit(
            CommitType::Docs,
            test_scope("api_docs"),
            test_description("update README"),
            BreakingChange::No,
        );
        assert_eq!(commit2.format(), "docs(api_docs): update README");

        // Scope with slash (Jira-style)
        let commit3 = test_commit(
            CommitType::Chore,
            test_scope("PROJ-123/cleanup"),
            test_description("remove unused code"),
            BreakingChange::No,
        );
        assert_eq!(
            commit3.format(),
            "chore(PROJ-123/cleanup): remove unused code"
        );
    }

    /// Test that format() produces "type: description" when scope is empty
    #[test]
    fn format_without_scope_produces_correct_output() {
        let commit = test_commit(
            CommitType::Feat,
            Scope::empty(),
            test_description("add login"),
            BreakingChange::No,
        );
        assert_eq!(commit.format(), "feat: add login");
    }

    /// Test format without scope for various descriptions
    #[test]
    fn format_without_scope_various_descriptions() {
        let commit1 = test_commit(
            CommitType::Fix,
            Scope::empty(),
            test_description("fix critical bug"),
            BreakingChange::No,
        );
        assert_eq!(commit1.format(), "fix: fix critical bug");

        let commit2 = test_commit(
            CommitType::Docs,
            Scope::empty(),
            test_description("update installation guide"),
            BreakingChange::No,
        );
        assert_eq!(commit2.format(), "docs: update installation guide");
    }

    /// Test that all 11 commit types format correctly with scope
    #[test]
    fn all_commit_types_format_correctly_with_scope() {
        let scope = test_scope("cli");
        let desc = test_description("test change");

        let expected_formats = [
            (CommitType::Feat, "feat(cli): test change"),
            (CommitType::Fix, "fix(cli): test change"),
            (CommitType::Docs, "docs(cli): test change"),
            (CommitType::Style, "style(cli): test change"),
            (CommitType::Refactor, "refactor(cli): test change"),
            (CommitType::Perf, "perf(cli): test change"),
            (CommitType::Test, "test(cli): test change"),
            (CommitType::Build, "build(cli): test change"),
            (CommitType::Ci, "ci(cli): test change"),
            (CommitType::Chore, "chore(cli): test change"),
            (CommitType::Revert, "revert(cli): test change"),
        ];

        for (commit_type, expected) in expected_formats {
            let commit = test_commit(commit_type, scope.clone(), desc.clone(), BreakingChange::No);
            assert_eq!(
                commit.format(),
                expected,
                "Format should be correct for {:?}",
                commit_type
            );
        }
    }

    /// Test that all 11 commit types format correctly without scope
    #[test]
    fn all_commit_types_format_correctly_without_scope() {
        let desc = test_description("test change");

        let expected_formats = [
            (CommitType::Feat, "feat: test change"),
            (CommitType::Fix, "fix: test change"),
            (CommitType::Docs, "docs: test change"),
            (CommitType::Style, "style: test change"),
            (CommitType::Refactor, "refactor: test change"),
            (CommitType::Perf, "perf: test change"),
            (CommitType::Test, "test: test change"),
            (CommitType::Build, "build: test change"),
            (CommitType::Ci, "ci: test change"),
            (CommitType::Chore, "chore: test change"),
            (CommitType::Revert, "revert: test change"),
        ];

        for (commit_type, expected) in expected_formats {
            let commit = test_commit(
                commit_type,
                Scope::empty(),
                desc.clone(),
                BreakingChange::No,
            );
            assert_eq!(
                commit.format(),
                expected,
                "Format should be correct for {:?}",
                commit_type
            );
        }
    }

    /// Test that Display implementation delegates to format()
    #[test]
    fn display_delegates_to_format() {
        let commit = test_commit(
            CommitType::Feat,
            test_scope("auth"),
            test_description("add login"),
            BreakingChange::No,
        );
        let display_output = format!("{}", commit);
        let format_output = commit.format();
        assert_eq!(display_output, format_output);
    }

    /// Test Display with scope
    #[test]
    fn display_with_scope() {
        let commit = test_commit(
            CommitType::Fix,
            test_scope("api"),
            test_description("handle null response"),
            BreakingChange::No,
        );
        assert_eq!(format!("{}", commit), "fix(api): handle null response");
    }

    /// Test Display without scope
    #[test]
    fn display_without_scope() {
        let commit = test_commit(
            CommitType::Docs,
            Scope::empty(),
            test_description("improve README"),
            BreakingChange::No,
        );
        assert_eq!(format!("{}", commit), "docs: improve README");
    }

    /// Test Display delegates to format for all commit types
    #[test]
    fn display_equals_format_for_all_types() {
        for commit_type in CommitType::all() {
            // With scope
            let commit_with_scope = test_commit(
                *commit_type,
                test_scope("test"),
                test_description("change"),
                BreakingChange::No,
            );
            assert_eq!(
                format!("{}", commit_with_scope),
                commit_with_scope.format(),
                "Display should equal format() for {:?} with scope",
                commit_type
            );

            // Without scope
            let commit_without_scope = test_commit(
                *commit_type,
                Scope::empty(),
                test_description("change"),
                BreakingChange::No,
            );
            assert_eq!(
                format!("{}", commit_without_scope),
                commit_without_scope.format(),
                "Display should equal format() for {:?} without scope",
                commit_type
            );
        }
    }

    /// Test Clone trait
    #[test]
    fn conventional_commit_is_cloneable() {
        let original = test_commit(
            CommitType::Feat,
            test_scope("cli"),
            test_description("add feature"),
            BreakingChange::No,
        );
        let cloned = original.clone();
        assert_eq!(original, cloned);
    }

    /// Test PartialEq trait - equal commits
    #[test]
    fn conventional_commit_equality() {
        let commit1 = test_commit(
            CommitType::Feat,
            test_scope("cli"),
            test_description("add feature"),
            BreakingChange::No,
        );
        let commit2 = test_commit(
            CommitType::Feat,
            test_scope("cli"),
            test_description("add feature"),
            BreakingChange::No,
        );
        assert_eq!(commit1, commit2);
    }

    /// Test PartialEq trait - different commit types
    #[test]
    fn conventional_commit_inequality_different_type() {
        let commit1 = test_commit(
            CommitType::Feat,
            test_scope("cli"),
            test_description("change"),
            BreakingChange::No,
        );
        let commit2 = test_commit(
            CommitType::Fix,
            test_scope("cli"),
            test_description("change"),
            BreakingChange::No,
        );
        assert_ne!(commit1, commit2);
    }

    /// Test PartialEq trait - different scopes
    #[test]
    fn conventional_commit_inequality_different_scope() {
        let commit1 = test_commit(
            CommitType::Feat,
            test_scope("cli"),
            test_description("change"),
            BreakingChange::No,
        );
        let commit2 = test_commit(
            CommitType::Feat,
            test_scope("api"),
            test_description("change"),
            BreakingChange::No,
        );
        assert_ne!(commit1, commit2);
    }

    /// Test PartialEq trait - different descriptions
    #[test]
    fn conventional_commit_inequality_different_description() {
        let commit1 = test_commit(
            CommitType::Feat,
            test_scope("cli"),
            test_description("add feature"),
            BreakingChange::No,
        );
        let commit2 = test_commit(
            CommitType::Feat,
            test_scope("cli"),
            test_description("fix bug"),
            BreakingChange::No,
        );
        assert_ne!(commit1, commit2);
    }

    /// Test Debug trait
    #[test]
    fn conventional_commit_has_debug() {
        let commit = test_commit(
            CommitType::Feat,
            test_scope("cli"),
            test_description("add feature"),
            BreakingChange::No,
        );
        let debug_output = format!("{:?}", commit);
        assert!(debug_output.contains("ConventionalCommit"));
        assert!(debug_output.contains("Feat"));
    }

    /// Test real-world commit message example: feature with scope
    #[test]
    fn real_world_feature_with_scope() {
        let commit = test_commit(
            CommitType::Feat,
            test_scope("auth"),
            test_description("implement OAuth2 login flow"),
            BreakingChange::No,
        );
        assert_eq!(commit.format(), "feat(auth): implement OAuth2 login flow");
    }

    /// Test real-world commit message example: bug fix without scope
    #[test]
    fn real_world_bugfix_without_scope() {
        let commit = test_commit(
            CommitType::Fix,
            Scope::empty(),
            test_description("prevent crash on empty input"),
            BreakingChange::No,
        );
        assert_eq!(commit.format(), "fix: prevent crash on empty input");
    }

    /// Test real-world commit message example: documentation
    #[test]
    fn real_world_docs() {
        let commit = test_commit(
            CommitType::Docs,
            test_scope("README"),
            test_description("add installation instructions"),
            BreakingChange::No,
        );
        assert_eq!(
            commit.format(),
            "docs(README): add installation instructions"
        );
    }

    /// Test real-world commit message example: refactoring
    #[test]
    fn real_world_refactor() {
        let commit = test_commit(
            CommitType::Refactor,
            test_scope("core"),
            test_description("extract validation logic"),
            BreakingChange::No,
        );
        assert_eq!(commit.format(), "refactor(core): extract validation logic");
    }

    /// Test real-world commit message example: CI change
    #[test]
    fn real_world_ci() {
        let commit = test_commit(
            CommitType::Ci,
            test_scope("github"),
            test_description("add release workflow"),
            BreakingChange::No,
        );
        assert_eq!(commit.format(), "ci(github): add release workflow");
    }

    /// Test commit message with maximum description length (50 chars)
    #[test]
    fn format_with_max_length_description() {
        let long_desc = "a".repeat(50);
        let commit = test_commit(
            CommitType::Feat,
            Scope::empty(),
            Description::parse(&long_desc).unwrap(),
            BreakingChange::No,
        );
        // Format should be "feat: " + 50 chars = 56 total chars
        let formatted = commit.format();
        assert!(formatted.starts_with("feat: "));
        assert_eq!(formatted.len(), 56); // "feat: " (6) + 50 = 56
    }

    /// Test commit message with scope containing all valid special chars
    #[test]
    fn format_with_complex_scope() {
        let commit = test_commit(
            CommitType::Feat,
            test_scope("my-scope_v2/feature"),
            test_description("add support"),
            BreakingChange::No,
        );
        assert_eq!(commit.format(), "feat(my-scope_v2/feature): add support");
    }

    /// Test FIRST_LINE_MAX_LENGTH constant is 72
    #[test]
    fn first_line_max_length_constant_is_72() {
        assert_eq!(ConventionalCommit::FIRST_LINE_MAX_LENGTH, 72);
    }

    /// Test first_line_len() calculates correctly without scope
    #[test]
    fn first_line_len_without_scope() {
        let commit = test_commit(
            CommitType::Feat,
            Scope::empty(),
            test_description("add login"),
            BreakingChange::No,
        );
        // "feat: add login" = 4 + 2 + 9 = 15
        assert_eq!(commit.first_line_len(), 15);
    }

    /// Test first_line_len() calculates correctly with scope
    #[test]
    fn first_line_len_with_scope() {
        let commit = test_commit(
            CommitType::Feat,
            test_scope("auth"),
            test_description("add login"),
            BreakingChange::No,
        );
        // "feat(auth): add login" = 4 + 4 + 4 + 9 = 21
        assert_eq!(commit.first_line_len(), 21);
    }

    /// Test exactly 72 characters is accepted (boundary)
    #[test]
    fn exactly_72_characters_accepted() {
        // Build a commit that's exactly 72 chars:
        // feat(20chars): 44chars = 4 + 20 + 4 + 44 = 72
        let scope_20 = "a".repeat(20);
        let desc_44 = "b".repeat(44);
        let result = ConventionalCommit::new(
            CommitType::Feat,
            Scope::parse(&scope_20).unwrap(),
            Description::parse(&desc_44).unwrap(),
            BreakingChange::No,
            Body::default(),
            References::default(),
        );
        assert!(result.is_ok());
        let commit = result.unwrap();
        assert_eq!(commit.first_line_len(), 72);
    }

    /// Test 73 characters is rejected (boundary)
    #[test]
    fn seventy_three_characters_rejected() {
        // Build a commit that's 73 chars:
        // "refactor: " = 10 chars, so we need 63 chars of description for 73 total
        // But wait, we need to account for commit type and potentially scope
        // Let's use "feat" (4) + ": " (2) + 67 chars = 73
        // However Description MAX_LENGTH is 50, so we need a different approach
        // Use scope to pad: "refactor(scope): desc"
        // refactor = 8, (scope) = 7, : = 1, space = 1, desc needed for 73
        // 8 + 7 + 2 + desc = 73, so desc = 56, but max is 50
        // Let's use a longer type: "refactor" (8) + longer scope
        // Actually, let me use max scope (30) and appropriate description:
        // type(scope): desc
        // refactor(30chars): X = 8 + 30 + 4 + X = 73
        // X = 73 - 42 = 31
        let scope_30 = "a".repeat(30);
        let desc_31 = "b".repeat(31);
        let result = ConventionalCommit::new(
            CommitType::Refactor,
            Scope::parse(&scope_30).unwrap(),
            Description::parse(&desc_31).unwrap(),
            BreakingChange::No,
            Body::default(),
            References::default(),
        );
        assert!(result.is_err());
        assert_eq!(
            result.unwrap_err(),
            CommitMessageError::FirstLineTooLong {
                actual: 73,
                max: 72
            }
        );
    }

    /// Test that valid components can still exceed 72 chars when combined
    #[test]
    fn valid_components_can_exceed_limit() {
        // Use maximum valid scope (30 chars) and a 40-char description
        // refactor(30): 40 = 8 + 30 + 4 + 40 = 82 chars (exceeds 72)
        let scope_30 = "a".repeat(30);
        let desc_40 = "b".repeat(40);
        let result = ConventionalCommit::new(
            CommitType::Refactor,
            Scope::parse(&scope_30).unwrap(),
            Description::parse(&desc_40).unwrap(),
            BreakingChange::No,
            Body::default(),
            References::default(),
        );
        assert!(result.is_err());
        assert_eq!(
            result.unwrap_err(),
            CommitMessageError::FirstLineTooLong {
                actual: 82,
                max: 72
            }
        );
    }

    /// Test short commit without scope is accepted
    #[test]
    fn short_commit_without_scope_accepted() {
        let result = ConventionalCommit::new(
            CommitType::Fix,
            Scope::empty(),
            test_description("quick fix"),
            BreakingChange::No,
            Body::default(),
            References::default(),
        );
        assert!(result.is_ok());
    }

    /// Test short commit with scope is accepted
    #[test]
    fn short_commit_with_scope_accepted() {
        let result = ConventionalCommit::new(
            CommitType::Feat,
            test_scope("cli"),
            test_description("add feature"),
            BreakingChange::No,
            Body::default(),
            References::default(),
        );
        assert!(result.is_ok());
    }

    /// Test CommitMessageError::FirstLineTooLong displays correctly
    #[test]
    fn first_line_too_long_error_display() {
        let err = CommitMessageError::FirstLineTooLong {
            actual: 80,
            max: 72,
        };
        let msg = format!("{}", err);
        assert!(msg.contains("too long"));
        assert!(msg.contains("80"));
        assert!(msg.contains("72"));
    }

    /// Test new() returns Result type
    #[test]
    fn new_returns_result() {
        let result = ConventionalCommit::new(
            CommitType::Feat,
            Scope::empty(),
            test_description("test"),
            BreakingChange::No,
            Body::default(),
            References::default(),
        );
        // Just verify it's a Result by using is_ok()
        assert!(result.is_ok());
    }

    /// Test that all valid commits produce messages parseable by git-conventional (SC-002)
    ///
    /// This verifies that 100% of commit messages produced by this tool conform to
    /// the conventional commit specification.
    #[test]
    fn all_valid_commits_parse_with_git_conventional() {
        let cases: &[(&str, Option<&str>)] = &[
            ("add new feature", None),
            ("fix critical bug", Some("api")),
            ("update README", Some("docs")),
            ("remove unused code", Some("core")),
        ];

        for commit_type in CommitType::all() {
            for (desc_str, scope_str) in cases {
                let scope = match scope_str {
                    Some(s) => Scope::parse(*s).unwrap(),
                    None => Scope::empty(),
                };
                let desc = Description::parse(*desc_str).unwrap();
                let commit = ConventionalCommit::new(
                    *commit_type,
                    scope,
                    desc,
                    BreakingChange::No,
                    Body::default(),
                    References::default(),
                );
                // new() itself calls git_conventional::Commit::parse internally, so
                // if this is Ok, SC-002 is satisfied for this case.
                assert!(
                    commit.is_ok(),
                    "git-conventional rejected {:?}/{:?}/{:?}",
                    commit_type,
                    scope_str,
                    desc_str
                );
            }
        }
    }

    /// Test InvalidConventionalFormat error displays correctly
    #[test]
    fn invalid_conventional_format_error_display() {
        let err = CommitMessageError::InvalidConventionalFormat {
            reason: "missing type".to_string(),
        };
        let msg = format!("{}", err);
        assert!(msg.contains("git-conventional"));
        assert!(msg.contains("missing type"));
    }

    /// Breaking change without note and without scope: header gets '!', no footer
    #[test]
    fn format_breaking_change_no_note_no_scope() {
        let commit = test_commit(
            CommitType::Feat,
            Scope::empty(),
            test_description("add login"),
            BreakingChange::Yes,
        );
        assert_eq!(commit.format(), "feat!: add login");
    }

    /// Breaking change without note and with scope: '!' goes after closing paren
    #[test]
    fn format_breaking_change_no_note_with_scope() {
        let commit = test_commit(
            CommitType::Feat,
            test_scope("auth"),
            test_description("add login"),
            BreakingChange::Yes,
        );
        assert_eq!(commit.format(), "feat(auth)!: add login");
    }

    /// Breaking change with note and without scope: footer is appended after a blank line
    #[test]
    fn format_breaking_change_with_note_no_scope() {
        let commit = test_commit(
            CommitType::Feat,
            Scope::empty(),
            test_description("drop Node 6"),
            "Node 6 is no longer supported".into(),
        );
        assert_eq!(
            commit.format(),
            "feat!: drop Node 6\n\nBREAKING CHANGE: Node 6 is no longer supported",
        );
    }

    /// Breaking change with note and with scope: both '!' and footer are present
    #[test]
    fn format_breaking_change_with_note_and_scope() {
        let commit = test_commit(
            CommitType::Fix,
            test_scope("api"),
            test_description("drop Node 6"),
            "Node 6 is no longer supported".into(),
        );
        assert_eq!(
            commit.format(),
            "fix(api)!: drop Node 6\n\nBREAKING CHANGE: Node 6 is no longer supported",
        );
    }

    /// Display with breaking change delegates to format() (no scope, with note)
    #[test]
    fn display_breaking_change_with_note() {
        let commit = test_commit(
            CommitType::Feat,
            Scope::empty(),
            test_description("drop Node 6"),
            "Node 6 is no longer supported".into(),
        );
        assert_eq!(
            format!("{}", commit),
            "feat!: drop Node 6\n\nBREAKING CHANGE: Node 6 is no longer supported",
        );
    }

    /// first_line_len() counts the '!' for a breaking change without scope
    ///
    /// "feat!: add login" = 4 + 1 + 2 + 9 = 16
    #[test]
    fn first_line_len_breaking_change_no_scope() {
        let commit = test_commit(
            CommitType::Feat,
            Scope::empty(),
            test_description("add login"),
            BreakingChange::Yes,
        );
        assert_eq!(commit.first_line_len(), 16);
    }

    /// first_line_len() counts the '!' for a breaking change with scope
    ///
    /// "feat(auth)!: add login" = 4 + 6 + 1 + 2 + 9 = 22
    #[test]
    fn first_line_len_breaking_change_with_scope() {
        let commit = test_commit(
            CommitType::Feat,
            test_scope("auth"),
            test_description("add login"),
            BreakingChange::Yes,
        );
        assert_eq!(commit.first_line_len(), 22);
    }

    /// The `!` counts toward the 72-character first-line limit
    ///
    /// The inputs below produce exactly 72 chars without a breaking change
    /// (covered by `exactly_72_characters_accepted`). With `!` they reach
    /// 73 and must be rejected.
    #[test]
    fn breaking_change_exclamation_counts_toward_line_limit() {
        let scope_20 = "a".repeat(20);
        let desc_44 = "b".repeat(44);
        let result = ConventionalCommit::new(
            CommitType::Feat,
            Scope::parse(&scope_20).unwrap(),
            Description::parse(&desc_44).unwrap(),
            BreakingChange::Yes,
            Body::default(),
            References::default(),
        );
        assert!(result.is_err());
        assert_eq!(
            result.unwrap_err(),
            CommitMessageError::FirstLineTooLong {
                actual: 73,
                max: 72
            },
        );
    }

    /// Breaking change footer does not count toward the 72-character first-line limit
    #[test]
    fn breaking_change_footer_does_not_count_toward_line_limit() {
        // First line is short; the note itself is long - should still be accepted.
        let long_note = "x".repeat(200);
        let result = ConventionalCommit::new(
            CommitType::Fix,
            Scope::empty(),
            test_description("quick fix"),
            long_note.into(),
            Body::default(),
            References::default(),
        );
        assert!(result.is_ok());
    }

    /// format_preview() static method produces the same result as format() for identical inputs
    #[test]
    fn format_preview_matches_format() {
        let commit = test_commit(
            CommitType::Feat,
            test_scope("auth"),
            test_description("add login"),
            BreakingChange::No,
        );
        let preview = ConventionalCommit::format_preview(
            commit.commit_type,
            &commit.scope,
            &commit.description,
            &BreakingChange::No,
            &Body::default(),
            &References::default(),
        );
        assert_eq!(preview, commit.format());
    }

    /// format_preview() with a breaking-change note produces the full multi-line message
    #[test]
    fn format_preview_breaking_change_with_note() {
        let preview = ConventionalCommit::format_preview(
            CommitType::Feat,
            &Scope::empty(),
            &test_description("drop legacy API"),
            &"removes legacy endpoint".into(),
            &Body::default(),
            &References::default(),
        );
        assert_eq!(
            preview,
            "feat!: drop legacy API\n\nBREAKING CHANGE: removes legacy endpoint"
        );
    }

    /// format_preview() with scope and breaking-change note
    #[test]
    fn format_preview_breaking_change_with_scope_and_note() {
        let preview = ConventionalCommit::format_preview(
            CommitType::Fix,
            &test_scope("api"),
            &test_description("drop Node 6"),
            &"Node 6 is no longer supported".into(),
            &Body::default(),
            &References::default(),
        );
        assert_eq!(
            preview,
            "fix(api)!: drop Node 6\n\nBREAKING CHANGE: Node 6 is no longer supported"
        );
    }

    /// Breaking-change footer is separated from the header by exactly one blank line
    #[test]
    fn format_breaking_change_footer_separator() {
        let commit = test_commit(
            CommitType::Fix,
            Scope::empty(),
            test_description("drop old API"),
            "old API removed".into(),
        );
        let formatted = commit.format();
        let parts: Vec<&str> = formatted.splitn(2, "\n\n").collect();
        assert_eq!(
            parts.len(),
            2,
            "expected header and footer separated by \\n\\n"
        );
        assert_eq!(parts[0], "fix!: drop old API");
        assert_eq!(parts[1], "BREAKING CHANGE: old API removed");
    }

    /// format() output has no leading or trailing whitespace for any variant
    #[test]
    fn format_has_no_surrounding_whitespace() {
        let no_bc = test_commit(
            CommitType::Feat,
            Scope::empty(),
            test_description("add feature"),
            BreakingChange::No,
        );
        let f = no_bc.format();
        assert_eq!(
            f,
            f.trim(),
            "format() must not have surrounding whitespace (no breaking change)"
        );

        let with_note = test_commit(
            CommitType::Fix,
            Scope::empty(),
            test_description("fix bug"),
            "important migration required".into(),
        );
        let f2 = with_note.format();
        assert_eq!(
            f2,
            f2.trim(),
            "format() must not have surrounding whitespace (with note)"
        );
    }

    /// All commit types format correctly with breaking change and no note
    #[test]
    fn all_commit_types_format_with_breaking_change_no_note() {
        let desc = test_description("test change");

        let expected_formats = [
            (CommitType::Feat, "feat!: test change"),
            (CommitType::Fix, "fix!: test change"),
            (CommitType::Docs, "docs!: test change"),
            (CommitType::Style, "style!: test change"),
            (CommitType::Refactor, "refactor!: test change"),
            (CommitType::Perf, "perf!: test change"),
            (CommitType::Test, "test!: test change"),
            (CommitType::Build, "build!: test change"),
            (CommitType::Ci, "ci!: test change"),
            (CommitType::Chore, "chore!: test change"),
            (CommitType::Revert, "revert!: test change"),
        ];

        for (commit_type, expected) in expected_formats {
            let commit = test_commit(
                commit_type,
                Scope::empty(),
                desc.clone(),
                BreakingChange::Yes,
            );
            assert_eq!(
                commit.format(),
                expected,
                "Format should be correct for {:?} with breaking change",
                commit_type
            );
        }
    }

    // --- Body tests (these will fail until format_preview() is updated to use body) ---

    /// format() includes the body between the header and an empty footer
    ///
    /// Case: body = Some, footer = "" → "type: desc\n\ncontent"
    #[test]
    fn format_with_body_no_breaking_change() {
        let commit = ConventionalCommit::new(
            CommitType::Feat,
            Scope::empty(),
            test_description("add feature"),
            BreakingChange::No,
            Body::from("This explains the change."),
            References::default(),
        )
        .unwrap();
        assert_eq!(
            commit.format(),
            "feat: add feature\n\nThis explains the change."
        );
    }

    /// format() includes the body when a scope is also present
    #[test]
    fn format_with_body_and_scope() {
        let commit = ConventionalCommit::new(
            CommitType::Fix,
            test_scope("api"),
            test_description("handle null response"),
            BreakingChange::No,
            Body::from("Null responses were previously unhandled."),
            References::default(),
        )
        .unwrap();
        assert_eq!(
            commit.format(),
            "fix(api): handle null response\n\nNull responses were previously unhandled."
        );
    }

    /// format() preserves internal newlines in a multi-paragraph body
    #[test]
    fn format_with_multiline_body() {
        let commit = ConventionalCommit::new(
            CommitType::Docs,
            Scope::empty(),
            test_description("update README"),
            BreakingChange::No,
            Body::from("First paragraph.\n\nSecond paragraph."),
            References::default(),
        )
        .unwrap();
        assert_eq!(
            commit.format(),
            "docs: update README\n\nFirst paragraph.\n\nSecond paragraph."
        );
    }

    /// format() places the body between the header and the breaking-change footer
    ///
    /// Case: body = Some, footer = Some → "type: desc\n\nbody\n\nBREAKING CHANGE: note"
    #[test]
    fn format_with_body_and_breaking_change_note() {
        let commit = ConventionalCommit::new(
            CommitType::Feat,
            Scope::empty(),
            test_description("drop legacy API"),
            "removes legacy endpoint".into(),
            Body::from("The endpoint was deprecated in v2."),
            References::default(),
        )
        .unwrap();
        assert_eq!(
            commit.format(),
            "feat!: drop legacy API\n\nThe endpoint was deprecated in v2.\n\nBREAKING CHANGE: removes legacy endpoint"
        );
    }

    /// format_preview() includes the body in the output
    #[test]
    fn format_preview_with_body() {
        let preview = ConventionalCommit::format_preview(
            CommitType::Feat,
            &Scope::empty(),
            &test_description("add feature"),
            &BreakingChange::No,
            &Body::from("This explains the change."),
            &References::default(),
        );
        assert_eq!(preview, "feat: add feature\n\nThis explains the change.");
    }

    /// format_preview() with body and breaking-change note produces the full message
    ///
    /// Case: body = Some, footer = Some → "type: desc\n\nbody\n\nBREAKING CHANGE: note"
    #[test]
    fn format_preview_with_body_and_breaking_change() {
        let preview = ConventionalCommit::format_preview(
            CommitType::Fix,
            &Scope::empty(),
            &test_description("drop old API"),
            &"old API removed".into(),
            &Body::from("Migration guide: see CHANGELOG."),
            &References::default(),
        );
        assert_eq!(
            preview,
            "fix!: drop old API\n\nMigration guide: see CHANGELOG.\n\nBREAKING CHANGE: old API removed"
        );
    }
}