rumdl 0.2.60

use crate::filtered_lines::FilteredLinesExt;
use crate::rule::{Fix, LintError, LintResult, LintWarning, Rule, RuleCategory, Severity};
/// Rule MD010: No tabs
///
/// See [docs/md010.md](../../docs/md010.md) for full documentation, configuration, and examples.
use crate::utils::range_utils::calculate_match_range;

pub mod md010_config;
pub use md010_config::MD010Config;

/// Rule MD010: Hard tabs
#[derive(Clone, Default)]
pub struct MD010NoHardTabs {
    config: MD010Config,
}

impl MD010NoHardTabs {
    pub fn new(spaces_per_tab: usize) -> Self {
        Self {
            config: MD010Config {
                spaces_per_tab: crate::types::PositiveUsize::from_const(spaces_per_tab),
                code_blocks: false,
                ..Default::default()
            },
        }
    }

    pub const fn from_config_struct(config: MD010Config) -> Self {
        Self { config }
    }

    fn count_leading_tabs(line: &str) -> usize {
        let mut count = 0;
        for c in line.chars() {
            if c == '\t' {
                count += 1;
            } else {
                break;
            }
        }
        count
    }

    /// The language an info string declares, or `""` when it declares none.
    ///
    /// Normally that is the first whitespace-separated word, so
    /// ```` ```makefile title="Makefile" ```` gives `makefile`. Two flavors write
    /// a language inside braces instead, and each is read only where it is real
    /// syntax: a Pandoc code-attribute block names it as the first `.class`
    /// (`{#id .makefile}` gives `makefile`), and a Quarto executable chunk names
    /// its engine (`{r, echo=FALSE}` gives `r`).
    fn fence_language(info_string: &str, flavor: crate::config::MarkdownFlavor) -> std::borrow::Cow<'_, str> {
        let info = info_string.trim();

        if flavor.is_pandoc_compatible()
            && let Some(class) = crate::utils::pandoc::pandoc_code_class_lang(info)
        {
            return std::borrow::Cow::Borrowed(class);
        }

        if flavor == crate::config::MarkdownFlavor::Quarto
            && crate::utils::quarto_chunks::is_executable_chunk(info)
            && let Some(header) = crate::utils::quarto_chunks::parse_inline_chunk_header(info)
        {
            return std::borrow::Cow::Owned(header.engine);
        }

        std::borrow::Cow::Borrowed(info.split_whitespace().next().unwrap_or(""))
    }

    /// Lines (1-indexed) belonging to a code block whose language is listed in
    /// `ignore-code-languages`.
    ///
    /// Covers CommonMark fences plus the Azure DevOps colon fences the parser
    /// never sees. An indented code block has no info string and can never match.
    fn ignored_language_lines(&self, ctx: &crate::lint_context::LintContext) -> std::collections::HashSet<usize> {
        let mut ignored = std::collections::HashSet::new();

        for detail in ctx.code_block_details.iter().chain(ctx.colon_fence_details()) {
            let label = Self::fence_language(&detail.info_string, ctx.flavor);
            if label.is_empty()
                || !self
                    .config
                    .ignore_code_languages
                    .iter()
                    .any(|listed| listed.eq_ignore_ascii_case(label.as_ref()))
            {
                continue;
            }

            let start_line = ctx
                .line_offsets
                .partition_point(|&off| off <= detail.start)
                .saturating_sub(1);
            let end_byte = detail.end.saturating_sub(1);
            let end_line = ctx
                .line_offsets
                .partition_point(|&off| off <= end_byte)
                .saturating_sub(1);
            for line in start_line..=end_line {
                ignored.insert(line + 1);
            }
        }

        ignored
    }

    fn find_and_group_tabs(line: &str) -> Vec<(usize, usize)> {
        let mut groups = Vec::new();
        let mut current_group_start: Option<usize> = None;
        let mut last_tab_pos = 0;

        for (i, c) in line.chars().enumerate() {
            if c == '\t' {
                if let Some(start) = current_group_start {
                    // We're in a group - check if this tab is consecutive
                    if i == last_tab_pos + 1 {
                        // Consecutive tab, continue the group
                        last_tab_pos = i;
                    } else {
                        // Gap found, save current group and start new one
                        groups.push((start, last_tab_pos + 1));
                        current_group_start = Some(i);
                        last_tab_pos = i;
                    }
                } else {
                    // Start a new group
                    current_group_start = Some(i);
                    last_tab_pos = i;
                }
            }
        }

        // Add the last group if there is one
        if let Some(start) = current_group_start {
            groups.push((start, last_tab_pos + 1));
        }

        groups
    }
}

impl Rule for MD010NoHardTabs {
    fn name(&self) -> &'static str {
        "MD010"
    }

    fn description(&self) -> &'static str {
        "No tabs"
    }

    fn check(&self, ctx: &crate::lint_context::LintContext) -> LintResult {
        let mut warnings = Vec::new();

        let mut filtered = ctx
            .filtered_lines()
            .skip_front_matter()
            .skip_html_comments()
            .skip_mdx_comments()
            .skip_html_blocks()
            .skip_pymdown_blocks()
            .skip_mkdocstrings()
            .skip_esm_blocks();

        if !self.config.code_blocks {
            filtered = filtered.skip_code_blocks();
        }

        // Testing code-blocks here only avoids building a set that cannot matter:
        // with it false the walk has already dropped every code block line.
        let ignored_lines = if self.config.code_blocks && !self.config.ignore_code_languages.is_empty() {
            self.ignored_language_lines(ctx)
        } else {
            std::collections::HashSet::new()
        };

        for filtered_line in filtered {
            if ignored_lines.contains(&filtered_line.line_num) {
                continue;
            }
            let line_num = filtered_line.line_num - 1;
            let line = filtered_line.content;

            // Process tabs directly without intermediate collection
            let tab_groups = Self::find_and_group_tabs(line);
            if tab_groups.is_empty() {
                continue;
            }

            let leading_tabs = Self::count_leading_tabs(line);

            // Generate warning for each group of consecutive tabs
            for (start_pos, end_pos) in tab_groups {
                let tab_count = end_pos - start_pos;
                let is_leading = start_pos < leading_tabs;

                // Calculate precise character range for the tab group
                let (start_line, start_col, end_line, end_col) =
                    calculate_match_range(line_num + 1, line, start_pos, tab_count);

                let message = if line.trim().is_empty() {
                    if tab_count == 1 {
                        "Empty line contains tab".to_string()
                    } else {
                        format!("Empty line contains {tab_count} tabs")
                    }
                } else if is_leading {
                    if tab_count == 1 {
                        format!(
                            "Found leading tab, use {} spaces instead",
                            self.config.spaces_per_tab.get()
                        )
                    } else {
                        format!(
                            "Found {} leading tabs, use {} spaces instead",
                            tab_count,
                            tab_count * self.config.spaces_per_tab.get()
                        )
                    }
                } else if tab_count == 1 {
                    "Found tab for alignment, use spaces instead".to_string()
                } else {
                    format!("Found {tab_count} tabs for alignment, use spaces instead")
                };

                warnings.push(LintWarning {
                    rule_name: Some(self.name().to_string()),
                    line: start_line,
                    column: start_col,
                    end_line,
                    end_column: end_col,
                    message,
                    severity: Severity::Warning,
                    fix: Some(Fix::new(
                        ctx.line_column_byte_range_with_length(line_num + 1, start_pos + 1, tab_count),
                        " ".repeat(tab_count * self.config.spaces_per_tab.get()),
                    )),
                });
            }
        }

        Ok(warnings)
    }

    fn fix(&self, ctx: &crate::lint_context::LintContext) -> Result<String, LintError> {
        if self.should_skip(ctx) {
            return Ok(ctx.content.to_string());
        }
        let warnings = self.check(ctx)?;
        if warnings.is_empty() {
            return Ok(ctx.content.to_string());
        }
        let warnings =
            crate::utils::fix_utils::filter_warnings_by_inline_config(warnings, ctx.inline_config(), self.name());
        crate::utils::fix_utils::apply_warning_fixes(ctx.content, &warnings)
            .map_err(crate::rule::LintError::InvalidInput)
    }

    fn as_any(&self) -> &dyn std::any::Any {
        self
    }

    fn should_skip(&self, ctx: &crate::lint_context::LintContext) -> bool {
        // Skip if content is empty or has no tabs
        ctx.content.is_empty() || !ctx.has_char('\t')
    }

    fn category(&self) -> RuleCategory {
        RuleCategory::Whitespace
    }

    crate::impl_rule_config_methods!(MD010Config);
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::lint_context::LintContext;
    use crate::rule::Rule;

    #[test]
    fn test_no_tabs() {
        let rule = MD010NoHardTabs::default();
        let content = "This is a line\nAnother line\nNo tabs here";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        assert!(result.is_empty());
    }

    #[test]
    fn test_single_tab() {
        let rule = MD010NoHardTabs::default();
        let content = "Line with\ttab";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        assert_eq!(result.len(), 1);
        assert_eq!(result[0].line, 1);
        assert_eq!(result[0].column, 10);
        assert_eq!(result[0].message, "Found tab for alignment, use spaces instead");
    }

    #[test]
    fn test_leading_tabs_skipped_in_indented_code_by_default() {
        // Both lines start with a tab at column 0: parsed as an indented code block.
        // Default code_blocks=false skips tabs in indented code blocks.
        let content = "\tIndented line\n\t\tDouble indented";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule_off = MD010NoHardTabs::default();
        let result_off = rule_off.check(&ctx).unwrap();
        assert!(
            result_off.is_empty(),
            "indented code block skipped by default, got {result_off:?}"
        );
        assert_eq!(
            rule_off.fix(&ctx).unwrap(),
            "\tIndented line\n\t\tDouble indented",
            "fix must preserve indented code block content"
        );

        // code_blocks=true: tabs inside indented code blocks are flagged.
        let rule_on = MD010NoHardTabs::from_config_struct(MD010Config {
            spaces_per_tab: crate::types::PositiveUsize::from_const(4),
            code_blocks: true,
            ..Default::default()
        });
        let result_on = rule_on.check(&ctx).unwrap();
        assert_eq!(result_on.len(), 2, "got {result_on:?}");
        assert_eq!(result_on[0].line, 1);
        assert_eq!(result_on[0].message, "Found leading tab, use 4 spaces instead");
        assert_eq!(result_on[1].line, 2);
        assert_eq!(result_on[1].message, "Found 2 leading tabs, use 8 spaces instead");
        assert_eq!(rule_on.fix(&ctx).unwrap(), "    Indented line\n        Double indented");
    }

    #[test]
    fn test_fix_tabs() {
        // Line 1 starts with a tab at column 0 -> indented code block, skipped by default.
        // Line 2 has a mid-line tab (alignment) -> flagged and fixed.
        let content = "\tIndented\nNormal\tline\nNo tabs";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule_off = MD010NoHardTabs::default();
        let warnings_off = rule_off.check(&ctx).unwrap();
        assert_eq!(warnings_off.len(), 1, "got {warnings_off:?}");
        assert_eq!(warnings_off[0].line, 2);
        assert_eq!(warnings_off[0].message, "Found tab for alignment, use spaces instead");
        assert_eq!(
            rule_off.fix(&ctx).unwrap(),
            "\tIndented\nNormal    line\nNo tabs",
            "indented code block line preserved; alignment tab fixed"
        );

        // code_blocks=true: line 1 is also flagged.
        let rule_on = MD010NoHardTabs::from_config_struct(MD010Config {
            spaces_per_tab: crate::types::PositiveUsize::from_const(4),
            code_blocks: true,
            ..Default::default()
        });
        let warnings_on = rule_on.check(&ctx).unwrap();
        assert_eq!(warnings_on.len(), 2, "got {warnings_on:?}");
        assert_eq!(warnings_on[0].line, 1);
        assert_eq!(warnings_on[1].line, 2);
        assert_eq!(rule_on.fix(&ctx).unwrap(), "    Indented\nNormal    line\nNo tabs");
    }

    #[test]
    fn test_custom_spaces_per_tab() {
        // Single tab at column 0 -> indented code block, skipped by default.
        let content = "\tIndented";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule_off = MD010NoHardTabs::new(4);
        assert!(
            rule_off.check(&ctx).unwrap().is_empty(),
            "indented code block skipped by default"
        );
        assert_eq!(
            rule_off.fix(&ctx).unwrap(),
            "\tIndented",
            "indented code block preserved by default"
        );

        // code_blocks=true: tab is flagged and fixed.
        let rule_on = MD010NoHardTabs::from_config_struct(MD010Config {
            spaces_per_tab: crate::types::PositiveUsize::from_const(4),
            code_blocks: true,
            ..Default::default()
        });
        assert_eq!(rule_on.check(&ctx).unwrap().len(), 1);
        assert_eq!(rule_on.fix(&ctx).unwrap(), "    Indented");
    }

    #[test]
    fn test_fenced_code_block_tabs_skipped_by_default() {
        let rule = MD010NoHardTabs::default();
        let content = "Normal\tline\n```\nCode\twith\ttab\n```\nAnother\tline";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        // By default (code_blocks=false) tabs inside code blocks are skipped
        assert_eq!(result.len(), 2);
        assert_eq!(result[0].line, 1);
        assert_eq!(result[1].line, 5);

        let fixed = rule.fix(&ctx).unwrap();
        assert_eq!(fixed, "Normal    line\n```\nCode\twith\ttab\n```\nAnother    line");
    }

    #[test]
    fn test_fenced_only_content_skipped_by_default() {
        let rule = MD010NoHardTabs::default();
        let content = "```\nCode\twith\ttab\n```";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        // By default (code_blocks=false) tabs in fenced code blocks are skipped
        // (e.g., Makefiles require tabs, Go uses tabs by convention)
        assert_eq!(result.len(), 0);
    }

    #[test]
    fn test_html_comments_ignored() {
        let rule = MD010NoHardTabs::default();
        let content = "Normal\tline\n<!-- HTML\twith\ttab -->\nAnother\tline";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        // Should not flag tabs in HTML comments
        assert_eq!(result.len(), 2);
        assert_eq!(result[0].line, 1);
        assert_eq!(result[1].line, 3);
    }

    #[test]
    fn test_multiline_html_comments() {
        let rule = MD010NoHardTabs::default();
        let content = "Before\n<!--\nMultiline\twith\ttabs\ncomment\t-->\nAfter\ttab";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        // Should only flag the tab after the comment
        assert_eq!(result.len(), 1);
        assert_eq!(result[0].line, 5);
    }

    #[test]
    fn test_empty_lines_with_tabs() {
        let rule = MD010NoHardTabs::default();
        let content = "Normal line\n\t\t\n\t\nAnother line";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        assert_eq!(result.len(), 2);
        assert_eq!(result[0].message, "Empty line contains 2 tabs");
        assert_eq!(result[1].message, "Empty line contains tab");
    }

    #[test]
    fn test_mixed_tabs_and_spaces() {
        // " \t..." (space then tab) and "\t ..." (tab then space): both parsed as
        // indented code blocks by the shared spec-compliant flag.
        // Default code_blocks=false skips them.
        let content = " \tMixed indentation\n\t Mixed again";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule_off = MD010NoHardTabs::default();
        let result_off = rule_off.check(&ctx).unwrap();
        assert!(
            result_off.is_empty(),
            "indented code block lines skipped, got {result_off:?}"
        );
        assert_eq!(
            rule_off.fix(&ctx).unwrap(),
            " \tMixed indentation\n\t Mixed again",
            "content preserved unchanged"
        );

        // code_blocks=true: both lines flagged.
        let rule_on = MD010NoHardTabs::from_config_struct(MD010Config {
            spaces_per_tab: crate::types::PositiveUsize::from_const(4),
            code_blocks: true,
            ..Default::default()
        });
        let result_on = rule_on.check(&ctx).unwrap();
        assert_eq!(result_on.len(), 2, "got {result_on:?}");
        assert_eq!(rule_on.fix(&ctx).unwrap(), "     Mixed indentation\n     Mixed again");
    }

    #[test]
    fn test_consecutive_tabs() {
        let rule = MD010NoHardTabs::default();
        let content = "Text\t\t\tthree tabs\tand\tanother";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        // Should group consecutive tabs
        assert_eq!(result.len(), 3);
        assert_eq!(result[0].message, "Found 3 tabs for alignment, use spaces instead");
    }

    #[test]
    fn test_find_and_group_tabs() {
        // Test finding and grouping tabs in one pass
        let groups = MD010NoHardTabs::find_and_group_tabs("a\tb\tc");
        assert_eq!(groups, vec![(1, 2), (3, 4)]);

        let groups = MD010NoHardTabs::find_and_group_tabs("\t\tabc");
        assert_eq!(groups, vec![(0, 2)]);

        let groups = MD010NoHardTabs::find_and_group_tabs("no tabs");
        assert!(groups.is_empty());

        // Test with consecutive and non-consecutive tabs
        let groups = MD010NoHardTabs::find_and_group_tabs("\t\t\ta\t\tb");
        assert_eq!(groups, vec![(0, 3), (4, 6)]);

        let groups = MD010NoHardTabs::find_and_group_tabs("\ta\tb\tc");
        assert_eq!(groups, vec![(0, 1), (2, 3), (4, 5)]);
    }

    #[test]
    fn test_count_leading_tabs() {
        assert_eq!(MD010NoHardTabs::count_leading_tabs("\t\tcode"), 2);
        assert_eq!(MD010NoHardTabs::count_leading_tabs(" \tcode"), 0);
        assert_eq!(MD010NoHardTabs::count_leading_tabs("no tabs"), 0);
        assert_eq!(MD010NoHardTabs::count_leading_tabs("\t"), 1);
    }

    #[test]
    fn test_default_config() {
        let rule = MD010NoHardTabs::default();
        let config = rule.default_config_section();
        assert!(config.is_some());
        let (name, _value) = config.unwrap();
        assert_eq!(name, "MD010");
    }

    #[test]
    fn test_from_config() {
        // "\tTab" at column 0 -> indented code block, skipped by default (code_blocks=false).
        let content_plain = "\tTab";
        let ctx_plain = LintContext::new(content_plain, crate::config::MarkdownFlavor::Standard, None);
        let rule_8_off = MD010NoHardTabs::new(8); // spaces_per_tab=8, code_blocks=false
        assert!(
            rule_8_off.check(&ctx_plain).unwrap().is_empty(),
            "indented code block skipped"
        );
        assert_eq!(
            rule_8_off.fix(&ctx_plain).unwrap(),
            "\tTab",
            "content preserved unchanged"
        );

        // code_blocks=true: the tab is flagged and replaced with 8 spaces.
        let rule_8_on = MD010NoHardTabs::from_config_struct(MD010Config {
            spaces_per_tab: crate::types::PositiveUsize::from_const(8),
            code_blocks: true,
            ..Default::default()
        });
        assert_eq!(rule_8_on.check(&ctx_plain).unwrap().len(), 1);
        assert_eq!(rule_8_on.fix(&ctx_plain).unwrap(), "        Tab");

        // Fenced code block: tab skipped by default.
        let content_fenced = "```\n\tTab in code\n```";
        let ctx_fenced = LintContext::new(content_fenced, crate::config::MarkdownFlavor::Standard, None);
        assert!(
            rule_8_off.check(&ctx_fenced).unwrap().is_empty(),
            "fenced code block skipped"
        );
        assert_eq!(rule_8_off.fix(&ctx_fenced).unwrap(), "```\n\tTab in code\n```");

        // code_blocks=true: tab inside fence is flagged.
        let result_on = rule_8_on.check(&ctx_fenced).unwrap();
        assert_eq!(result_on.len(), 1, "got {result_on:?}");
        assert_eq!(result_on[0].line, 2);
        assert_eq!(rule_8_on.fix(&ctx_fenced).unwrap(), "```\n        Tab in code\n```");
    }

    #[test]
    fn test_performance_large_document() {
        let rule = MD010NoHardTabs::default();
        let mut content = String::new();
        for i in 0..1000 {
            content.push_str(&format!("Line {i}\twith\ttabs\n"));
        }
        let ctx = LintContext::new(&content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        assert_eq!(result.len(), 2000);
    }

    #[test]
    fn test_preserve_content() {
        let rule = MD010NoHardTabs::default();
        let content = "**Bold**\ttext\n*Italic*\ttext\n[Link](url)\ttab";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let fixed = rule.fix(&ctx).unwrap();
        assert_eq!(fixed, "**Bold**    text\n*Italic*    text\n[Link](url)    tab");
    }

    #[test]
    fn test_edge_cases() {
        let rule = MD010NoHardTabs::default();

        // Tab at end of line
        let content = "Text\t";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        assert_eq!(result.len(), 1);

        // Only tabs
        let content = "\t\t\t";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        assert_eq!(result.len(), 1);
        assert_eq!(result[0].message, "Empty line contains 3 tabs");
    }

    #[test]
    fn test_fenced_code_block_tabs_preserved_in_fix_by_default() {
        let rule = MD010NoHardTabs::default();

        let content = "Text\twith\ttab\n```makefile\ntarget:\n\tcommand\n\tanother\n```\nMore\ttabs";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let fixed = rule.fix(&ctx).unwrap();

        // By default (code_blocks=false) tabs in fenced code blocks are preserved
        // (e.g., Makefiles require tabs, Go uses tabs by convention)
        let expected = "Text    with    tab\n```makefile\ntarget:\n\tcommand\n\tanother\n```\nMore    tabs";
        assert_eq!(fixed, expected);
    }

    #[test]
    fn test_tilde_fence_longer_than_3() {
        let rule = MD010NoHardTabs::default();
        // 5-tilde fenced code block should be recognized and tabs inside should be skipped
        let content = "~~~~~\ncode\twith\ttab\n~~~~~\ntext\twith\ttab";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        // Only tabs on line 4 (outside the code block) should be flagged
        assert_eq!(
            result.len(),
            2,
            "Expected 2 warnings but got {}: {:?}",
            result.len(),
            result
        );
        assert_eq!(result[0].line, 4);
        assert_eq!(result[1].line, 4);
    }

    #[test]
    fn test_backtick_fence_longer_than_3() {
        let rule = MD010NoHardTabs::default();
        // 5-backtick fenced code block
        let content = "`````\ncode\twith\ttab\n`````\ntext\twith\ttab";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        assert_eq!(
            result.len(),
            2,
            "Expected 2 warnings but got {}: {:?}",
            result.len(),
            result
        );
        assert_eq!(result[0].line, 4);
        assert_eq!(result[1].line, 4);
    }

    #[test]
    fn test_indented_code_block_tabs_skipped_by_default() {
        // "    code\twith\ttab" is indented with 4 spaces -> indented code block.
        // Default code_blocks=false skips it; only the tab on the normal line is flagged.
        let content = "    code\twith\ttab\n\nNormal\ttext";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule_off = MD010NoHardTabs::default();
        let result_off = rule_off.check(&ctx).unwrap();
        assert_eq!(
            result_off.len(),
            1,
            "expected 1 warning (only normal-text tab), got {}: {:?}",
            result_off.len(),
            result_off
        );
        assert_eq!(result_off[0].line, 3);
        assert_eq!(result_off[0].message, "Found tab for alignment, use spaces instead");

        // code_blocks=true: all 3 tabs flagged (2 on line 1, 1 on line 3).
        let rule_on = MD010NoHardTabs::from_config_struct(MD010Config {
            spaces_per_tab: crate::types::PositiveUsize::from_const(4),
            code_blocks: true,
            ..Default::default()
        });
        let result_on = rule_on.check(&ctx).unwrap();
        assert_eq!(
            result_on.len(),
            3,
            "expected 3 warnings with code_blocks=true, got {}: {:?}",
            result_on.len(),
            result_on
        );
        assert_eq!(result_on[0].line, 1);
        assert_eq!(result_on[1].line, 1);
        assert_eq!(result_on[2].line, 3);
    }

    #[test]
    fn test_html_comment_end_then_start_same_line() {
        let rule = MD010NoHardTabs::default();
        // Tabs inside consecutive HTML comments should not be flagged
        let content =
            "<!-- first comment\nend --> text <!-- second comment\n\ttabbed content inside second comment\n-->";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        assert!(
            result.is_empty(),
            "Expected 0 warnings but got {}: {:?}",
            result.len(),
            result
        );
    }

    #[test]
    fn test_fix_tilde_fence_longer_than_3() {
        let rule = MD010NoHardTabs::default();
        let content = "~~~~~\ncode\twith\ttab\n~~~~~\ntext\twith\ttab";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let fixed = rule.fix(&ctx).unwrap();
        // Tabs inside code block preserved, tabs outside replaced
        assert_eq!(fixed, "~~~~~\ncode\twith\ttab\n~~~~~\ntext    with    tab");
    }

    #[test]
    fn test_fix_indented_code_block_tabs_replaced() {
        // Default code_blocks=false: indented code block tabs preserved, normal-text tab fixed.
        let content = "    code\twith\ttab\n\nNormal\ttext";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule_off = MD010NoHardTabs::default();
        assert_eq!(
            rule_off.fix(&ctx).unwrap(),
            "    code\twith\ttab\n\nNormal    text",
            "indented code block preserved; only normal-text tab fixed"
        );

        // code_blocks=true: all tabs replaced including those in the indented code block.
        let rule_on = MD010NoHardTabs::from_config_struct(MD010Config {
            spaces_per_tab: crate::types::PositiveUsize::from_const(4),
            code_blocks: true,
            ..Default::default()
        });
        assert_eq!(
            rule_on.fix(&ctx).unwrap(),
            "    code    with    tab\n\nNormal    text",
            "all tabs replaced with code_blocks=true"
        );
    }

    #[test]
    fn test_issue_630_default_skips_both_code_blocks() {
        // Default code_blocks = false: tabs skipped in BOTH block types.
        let rule = MD010NoHardTabs::default();
        let content = "Foo bar\n\n    for range 100 {\n    \tfoo()\n    }\n\nThis is a fenced\n\n```\nfor range 100 {\n\tfoo()\n}\n```\n";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        assert!(result.is_empty(), "both code blocks skipped, got {result:?}");
    }

    #[test]
    fn test_issue_630_code_blocks_true_flags_both() {
        // code_blocks = true: tabs flagged in BOTH block types.
        let rule = MD010NoHardTabs::from_config_struct(MD010Config {
            spaces_per_tab: crate::types::PositiveUsize::from_const(4),
            code_blocks: true,
            ..Default::default()
        });
        let content = "Foo bar\n\n    for range 100 {\n    \tfoo()\n    }\n\nThis is a fenced\n\n```\nfor range 100 {\n\tfoo()\n}\n```\n";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        // Line 4 "    \tfoo()": one alignment tab group inside the indented block.
        // Line 11 "\tfoo()": one leading tab group inside the fenced block.
        assert_eq!(result.len(), 2, "got {result:?}");
        assert_eq!(result[0].line, 4);
        assert_eq!(result[1].line, 11);
    }

    #[test]
    fn test_code_blocks_toggle_fenced() {
        let content = "Normal\tline\n```\nCode\twith\ttab\n```\nAnother\tline";

        // Default false: only the two tab groups outside the fence.
        let off = MD010NoHardTabs::default();
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let r_off = off.check(&ctx).unwrap();
        assert_eq!(r_off.len(), 2, "got {r_off:?}");
        assert_eq!(r_off[0].line, 1);
        assert_eq!(r_off[1].line, 5);
        assert_eq!(
            off.fix(&ctx).unwrap(),
            "Normal    line\n```\nCode\twith\ttab\n```\nAnother    line"
        );

        // true: also the two groups on the fenced content line.
        let on = MD010NoHardTabs::from_config_struct(MD010Config {
            spaces_per_tab: crate::types::PositiveUsize::from_const(4),
            code_blocks: true,
            ..Default::default()
        });
        let r_on = on.check(&ctx).unwrap();
        assert_eq!(r_on.len(), 4, "got {r_on:?}");
        assert_eq!(r_on[0].line, 1);
        assert_eq!(r_on[1].line, 3);
        assert_eq!(r_on[2].line, 3);
        assert_eq!(r_on[3].line, 5);
        assert_eq!(
            on.fix(&ctx).unwrap(),
            "Normal    line\n```\nCode    with    tab\n```\nAnother    line"
        );
    }

    #[test]
    fn test_code_blocks_toggle_makefile_fence_preserved_by_default() {
        let content = "Text\twith\ttab\n```makefile\ntarget:\n\tcommand\n```\nMore\ttabs";
        let off = MD010NoHardTabs::default();
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        // Default preserves the Makefile recipe tab; only prose tabs fixed.
        assert_eq!(
            off.fix(&ctx).unwrap(),
            "Text    with    tab\n```makefile\ntarget:\n\tcommand\n```\nMore    tabs"
        );
    }

    #[test]
    fn test_ignore_code_languages_skips_a_listed_fence() {
        // code-blocks = true opts into checking tabs inside fences, but a tab in a
        // Makefile recipe is required syntax rather than a formatting mistake.
        let content = "Text\twith\ttab\n```makefile\ntarget:\n\tcommand\n```\n```sh\necho\thello\n```";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule = MD010NoHardTabs::from_config_struct(MD010Config {
            spaces_per_tab: crate::types::PositiveUsize::from_const(4),
            code_blocks: true,
            ignore_code_languages: vec!["makefile".to_string()],
        });

        let result = rule.check(&ctx).unwrap();
        let lines: Vec<usize> = result.iter().map(|w| w.line).collect();
        assert_eq!(
            lines,
            vec![1, 1, 7],
            "the makefile recipe tab on line 4 must be skipped, got {result:?}"
        );
        assert_eq!(
            rule.fix(&ctx).unwrap(),
            "Text    with    tab\n```makefile\ntarget:\n\tcommand\n```\n```sh\necho    hello\n```"
        );
    }

    #[test]
    fn test_ignore_code_languages_matches_the_label_case_insensitively() {
        // ```Makefile and ```makefile name the same language.
        let content = "```Makefile\ntarget:\n\tcommand\n```";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule = MD010NoHardTabs::from_config_struct(MD010Config {
            code_blocks: true,
            ignore_code_languages: vec!["makefile".to_string()],
            ..Default::default()
        });

        assert!(
            rule.check(&ctx).unwrap().is_empty(),
            "an uppercase fence label must match a lowercase configured language"
        );
    }

    #[test]
    fn test_ignore_code_languages_matches_only_the_first_info_string_word() {
        // The label is the first word, so attributes after it do not defeat the match.
        let labelled = "```makefile title=\"Makefile\"\ntarget:\n\tcommand\n```";
        let ctx = LintContext::new(labelled, crate::config::MarkdownFlavor::Standard, None);

        let rule = MD010NoHardTabs::from_config_struct(MD010Config {
            code_blocks: true,
            ignore_code_languages: vec!["makefile".to_string()],
            ..Default::default()
        });

        assert!(
            rule.check(&ctx).unwrap().is_empty(),
            "a fence carrying attributes after its language must still match"
        );

        // A different language on the same shape is still reported, so the match is
        // not simply accepting every labelled fence.
        let other = "```shell title=\"Makefile\"\ntarget:\n\tcommand\n```";
        let other_ctx = LintContext::new(other, crate::config::MarkdownFlavor::Standard, None);
        assert_eq!(
            rule.check(&other_ctx).unwrap().len(),
            1,
            "an unlisted language must still be reported"
        );
    }

    #[test]
    fn test_ignore_code_languages_cannot_match_an_indented_code_block() {
        // An indented code block has no info string, so it has no language to list.
        // Documented in docs/md010.md as a real gap.
        let content = "Text.\n\n    target:\n    \tcommand\n";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule = MD010NoHardTabs::from_config_struct(MD010Config {
            code_blocks: true,
            ignore_code_languages: vec!["makefile".to_string()],
            ..Default::default()
        });

        assert_eq!(
            rule.check(&ctx).unwrap().len(),
            1,
            "an indented block carries no language, so the list cannot exempt it"
        );
    }

    #[test]
    fn test_ignore_code_languages_is_inert_without_code_blocks() {
        // With code-blocks at its default the whole block is already skipped, so the
        // list changes nothing in either direction.
        let content = "```makefile\ntarget:\n\tcommand\n```\n```sh\necho\thello\n```";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule = MD010NoHardTabs::from_config_struct(MD010Config {
            ignore_code_languages: vec!["makefile".to_string()],
            ..Default::default()
        });

        assert!(
            rule.check(&ctx).unwrap().is_empty(),
            "listing a language must not start checking blocks that code-blocks skips"
        );
    }

    #[test]
    fn test_ignore_code_languages_matches_a_pandoc_class_attribute() {
        // Pandoc declares a fence's language as the first `.class` of its attribute
        // block, so ```{.makefile} names the same language as ```makefile.
        let content = "```{.makefile}\ntarget:\n\tcommand\n```";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Pandoc, None);

        let rule = MD010NoHardTabs::from_config_struct(MD010Config {
            code_blocks: true,
            ignore_code_languages: vec!["makefile".to_string()],
            ..Default::default()
        });

        assert!(
            rule.check(&ctx).unwrap().is_empty(),
            "the first .class of a Pandoc attribute block is the fence language"
        );

        // An unlisted class on the same shape is still reported.
        let other = "```{.shell}\ntarget:\n\tcommand\n```";
        let other_ctx = LintContext::new(other, crate::config::MarkdownFlavor::Pandoc, None);
        assert_eq!(
            rule.check(&other_ctx).unwrap().len(),
            1,
            "an unlisted class must still be reported"
        );
    }

    #[test]
    fn test_ignore_code_languages_class_attribute_needs_a_pandoc_compatible_flavor() {
        // Under `standard` braces are not attribute syntax, so the label stays raw
        // and cannot match a bare language name.
        let content = "```{.makefile}\ntarget:\n\tcommand\n```";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);

        let rule = MD010NoHardTabs::from_config_struct(MD010Config {
            code_blocks: true,
            ignore_code_languages: vec!["makefile".to_string()],
            ..Default::default()
        });

        assert_eq!(
            rule.check(&ctx).unwrap().len(),
            1,
            "attribute syntax must only be read under a Pandoc-compatible flavor"
        );
    }

    #[test]
    fn test_ignore_code_languages_matches_a_quarto_exec_chunk() {
        // A Quarto executable chunk names its engine inside the braces.
        let content = "```{r}\nx <- 1\n\tindented\n```";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Quarto, None);

        let rule = MD010NoHardTabs::from_config_struct(MD010Config {
            code_blocks: true,
            ignore_code_languages: vec!["r".to_string()],
            ..Default::default()
        });

        assert!(
            rule.check(&ctx).unwrap().is_empty(),
            "a `{{r}}` chunk declares language r"
        );

        // A chunk for a different engine is still reported.
        let python = "```{python}\nx = 1\n\tindented\n```";
        let python_ctx = LintContext::new(python, crate::config::MarkdownFlavor::Quarto, None);
        assert_eq!(
            rule.check(&python_ctx).unwrap().len(),
            1,
            "an unlisted engine must still be reported"
        );
    }

    #[test]
    fn test_ignore_code_languages_matches_an_azure_colon_fence() {
        // Azure DevOps colon fences carry their language on the opener.
        let rule = MD010NoHardTabs::from_config_struct(MD010Config {
            code_blocks: true,
            ignore_code_languages: vec!["makefile".to_string()],
            ..Default::default()
        });

        for content in [
            ":::makefile\ntarget:\n\tcommand\n:::",
            "::: makefile\ntarget:\n\tcommand\n:::",
        ] {
            let ctx = LintContext::new(content, crate::config::MarkdownFlavor::AzureDevOps, None);
            assert!(
                rule.check(&ctx).unwrap().is_empty(),
                "a colon fence's language must be honoured, got {:?} for {content:?}",
                rule.check(&ctx).unwrap()
            );
        }

        // An unlisted colon fence language is still reported.
        let other = ":::mermaid\nflowchart LR\n\tA --> B\n:::";
        let other_ctx = LintContext::new(other, crate::config::MarkdownFlavor::AzureDevOps, None);
        assert_eq!(
            rule.check(&other_ctx).unwrap().len(),
            1,
            "an unlisted colon fence language must still be reported"
        );
    }

    #[test]
    fn test_tabs_in_front_matter_are_not_flagged() {
        // Hard tabs inside YAML front matter are metadata, not Markdown body,
        // and must not be reported.
        let rule = MD010NoHardTabs::default();
        let content = "---\ntitle:\t\"Tabbed value\"\n---\n\n# Heading\n\nBody text.\n";
        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard, None);
        let result = rule.check(&ctx).unwrap();
        assert!(
            result.is_empty(),
            "tabs inside front matter must not be flagged, got: {result:?}"
        );
    }
}