rumdl_lib/rules/
md042_no_empty_links.rs

1use crate::rule::{Fix, LintError, LintResult, LintWarning, Rule, RuleCategory, Severity};
2use crate::utils::mkdocs_patterns::is_mkdocs_auto_reference;
3
4/// Rule MD042: No empty links
5///
6/// See [docs/md042.md](../../docs/md042.md) for full documentation, configuration, and examples.
7///
8/// This rule is triggered when a link has no content (text) or destination (URL).
9///
10/// # MkDocs Support
11///
12/// When `flavor = "mkdocs"` is configured, this rule recognizes two types of valid MkDocs patterns:
13///
14/// ## 1. Auto-References (via mkdocs-autorefs / mkdocstrings)
15///
16/// Backtick-wrapped Python identifiers used for cross-referencing:
17/// ```markdown
18/// [`module.Class`][]     // Python class reference
19/// [`str`][]              // Built-in type reference
20/// [`api.function`][]     // Function reference
21/// ```
22///
23/// **References:**
24/// - [mkdocs-autorefs](https://mkdocstrings.github.io/autorefs/)
25/// - [mkdocstrings](https://mkdocstrings.github.io/)
26///
27/// ## 2. Paragraph Anchors (via Python-Markdown attr_list extension)
28///
29/// Empty links combined with attributes to create anchor points:
30/// ```markdown
31/// [](){ #my-anchor }              // Basic anchor
32/// [](){ #anchor .class }          // Anchor with CSS class
33/// [](){: #anchor }                // With colon (canonical attr_list syntax)
34/// [](){ .class1 .class2 }         // Classes only
35/// ```
36///
37/// This syntax combines:
38/// - Empty link `[]()` → creates `<a href=""></a>`
39/// - attr_list syntax `{ #id }` → adds attributes to preceding element
40/// - Result: `<a href="" id="my-anchor"></a>`
41///
42/// **References:**
43/// - [Python-Markdown attr_list](https://python-markdown.github.io/extensions/attr_list/)
44/// - [MkDocs discussion](https://github.com/mkdocs/mkdocs/discussions/3754)
45///
46/// **Implementation:** See [`is_mkdocs_attribute_anchor`](Self::is_mkdocs_attribute_anchor)
47#[derive(Clone, Default)]
48pub struct MD042NoEmptyLinks {}
49
50impl MD042NoEmptyLinks {
51    pub fn new() -> Self {
52        Self {}
53    }
54
55    /// Strip surrounding backticks from a string
56    /// Used for MkDocs auto-reference detection where `module.Class` should be treated as module.Class
57    fn strip_backticks(s: &str) -> &str {
58        s.trim_start_matches('`').trim_end_matches('`')
59    }
60
61    /// Check if a string is a valid Python identifier
62    /// Python identifiers can contain alphanumeric characters and underscores, but cannot start with a digit
63    fn is_valid_python_identifier(s: &str) -> bool {
64        if s.is_empty() {
65            return false;
66        }
67
68        let first_char = s.chars().next().unwrap();
69        if !first_char.is_ascii_alphabetic() && first_char != '_' {
70            return false;
71        }
72
73        s.chars().all(|c| c.is_ascii_alphanumeric() || c == '_')
74    }
75
76    /// Check if an empty link is followed by MkDocs attribute syntax
77    /// Pattern: []() followed by { #anchor } or { #anchor .class }
78    ///
79    /// This validates the Python-Markdown attr_list extension syntax when applied to empty links.
80    /// Empty links `[]()` combined with attributes like `{ #anchor }` create anchor points in
81    /// documentation, as documented by mkdocs-autorefs and the attr_list extension.
82    fn is_mkdocs_attribute_anchor(content: &str, link_end: usize) -> bool {
83        // UTF-8 safety: Validate byte position is at character boundary
84        if !content.is_char_boundary(link_end) {
85            return false;
86        }
87
88        // Get the content after the link
89        if let Some(rest) = content.get(link_end..) {
90            // Trim whitespace and check if it starts with {
91            // Note: trim_start() removes all whitespace including newlines
92            // This is intentionally permissive to match real-world MkDocs usage
93            let trimmed = rest.trim_start();
94
95            // Check for opening brace (with optional colon per attr_list spec)
96            let stripped = if let Some(s) = trimmed.strip_prefix("{:") {
97                s
98            } else if let Some(s) = trimmed.strip_prefix('{') {
99                s
100            } else {
101                return false;
102            };
103
104            // Look for closing brace
105            if let Some(end_brace) = stripped.find('}') {
106                // DoS prevention: Limit attribute section length
107                if end_brace > 500 {
108                    return false;
109                }
110
111                let attrs = stripped[..end_brace].trim();
112
113                // Empty attributes should not be considered valid
114                if attrs.is_empty() {
115                    return false;
116                }
117
118                // Check if it contains an anchor (starts with #) or class (starts with .)
119                // Valid patterns: { #anchor }, { #anchor .class }, { .class #anchor }
120                // At least one attribute starting with # or . is required
121                return attrs
122                    .split_whitespace()
123                    .any(|part| part.starts_with('#') || part.starts_with('.'));
124            }
125        }
126        false
127    }
128}
129
130impl Rule for MD042NoEmptyLinks {
131    fn name(&self) -> &'static str {
132        "MD042"
133    }
134
135    fn description(&self) -> &'static str {
136        "No empty links"
137    }
138
139    fn check(&self, ctx: &crate::lint_context::LintContext) -> LintResult {
140        let mut warnings = Vec::new();
141
142        // Check if we're in MkDocs mode from the context
143        let mkdocs_mode = ctx.flavor == crate::config::MarkdownFlavor::MkDocs;
144
145        // Use centralized link parsing from LintContext
146        for link in &ctx.links {
147            // Skip links inside Jinja templates
148            if ctx.is_in_jinja_range(link.byte_offset) {
149                continue;
150            }
151
152            // Skip links inside HTML tags (e.g., <a href="...?p[images][0]=...">)
153            // Check if the link's byte position falls within any HTML tag range
154            let in_html_tag = ctx
155                .html_tags()
156                .iter()
157                .any(|html_tag| html_tag.byte_offset <= link.byte_offset && link.byte_offset < html_tag.byte_end);
158            if in_html_tag {
159                continue;
160            }
161
162            // For reference links, resolve the URL
163            let effective_url = if link.is_reference {
164                if let Some(ref_id) = &link.reference_id {
165                    ctx.get_reference_url(ref_id).unwrap_or("").to_string()
166                } else {
167                    String::new()
168                }
169            } else {
170                link.url.clone()
171            };
172
173            // For MkDocs mode, check if this looks like an auto-reference
174            // Note: We check both the reference_id AND the text since shorthand references
175            // like [class.Name][] use the text as the implicit reference
176            // Also strip backticks since MkDocs resolves `module.Class` as module.Class
177            if mkdocs_mode && link.is_reference {
178                // Check the reference_id if present (strip backticks first)
179                if let Some(ref_id) = &link.reference_id {
180                    let stripped_ref = Self::strip_backticks(ref_id);
181                    // Accept if it matches MkDocs patterns OR if it's a backtick-wrapped valid identifier
182                    // Backticks indicate code/type reference (like `str`, `int`, `MyClass`)
183                    if is_mkdocs_auto_reference(stripped_ref)
184                        || (ref_id != stripped_ref && Self::is_valid_python_identifier(stripped_ref))
185                    {
186                        continue;
187                    }
188                }
189                // Also check the link text itself for shorthand references (strip backticks)
190                let stripped_text = Self::strip_backticks(&link.text);
191                // Accept if it matches MkDocs patterns OR if it's a backtick-wrapped valid identifier
192                if is_mkdocs_auto_reference(stripped_text)
193                    || (link.text.as_str() != stripped_text && Self::is_valid_python_identifier(stripped_text))
194                {
195                    continue;
196                }
197            }
198
199            // Skip autolinks (like <https://example.com>)
200            // Autolinks are valid CommonMark syntax: <URL> where text field is empty but URL is the display
201            // Detect by checking if source markdown is wrapped in < and >
202            let link_markdown = &ctx.content[link.byte_offset..link.byte_end];
203            if link_markdown.starts_with('<') && link_markdown.ends_with('>') {
204                continue;
205            }
206
207            // Check for empty links
208            if link.text.trim().is_empty() || effective_url.trim().is_empty() {
209                // In MkDocs mode, check if this is an attribute anchor: []() followed by { #anchor }
210                if mkdocs_mode
211                    && link.text.trim().is_empty()
212                    && effective_url.trim().is_empty()
213                    && Self::is_mkdocs_attribute_anchor(ctx.content, link.byte_end)
214                {
215                    // This is a valid MkDocs attribute anchor, skip it
216                    continue;
217                }
218
219                // Determine if we can provide a meaningful fix
220                let replacement = if link.text.trim().is_empty() {
221                    // Empty text - can we fix it?
222                    if !effective_url.trim().is_empty() {
223                        // Has URL but no text - add placeholder text
224                        if link.is_reference {
225                            Some(format!(
226                                "[Link text]{}",
227                                &ctx.content[link.byte_offset + 1..link.byte_end]
228                            ))
229                        } else {
230                            Some(format!("[Link text]({effective_url})"))
231                        }
232                    } else {
233                        // Both empty - can't meaningfully auto-fix
234                        None
235                    }
236                } else if link.is_reference {
237                    // Reference links with text but no/empty reference - keep the format
238                    let ref_part = &ctx.content[link.byte_offset + link.text.len() + 2..link.byte_end];
239                    Some(format!("[{}]{}", link.text, ref_part))
240                } else {
241                    // URL is empty, but text is not
242                    // Check if the link text looks like a URL - if so, use it as the destination
243                    let text_is_url = link.text.starts_with("http://")
244                        || link.text.starts_with("https://")
245                        || link.text.starts_with("ftp://")
246                        || link.text.starts_with("ftps://");
247
248                    if text_is_url {
249                        Some(format!("[{}]({})", link.text, link.text))
250                    } else {
251                        // Text is not a URL - can't meaningfully auto-fix
252                        None
253                    }
254                };
255
256                // Extract the exact link text from the source
257                let link_display = &ctx.content[link.byte_offset..link.byte_end];
258
259                warnings.push(LintWarning {
260                    rule_name: Some(self.name().to_string()),
261                    message: format!("Empty link found: {link_display}"),
262                    line: link.line,
263                    column: link.start_col + 1, // Convert to 1-indexed
264                    end_line: link.line,
265                    end_column: link.end_col + 1, // Convert to 1-indexed
266                    severity: Severity::Warning,
267                    fix: replacement.map(|r| Fix {
268                        range: link.byte_offset..link.byte_end,
269                        replacement: r,
270                    }),
271                });
272            }
273        }
274
275        Ok(warnings)
276    }
277
278    fn fix(&self, ctx: &crate::lint_context::LintContext) -> Result<String, LintError> {
279        let content = ctx.content;
280
281        // Get all warnings first - only fix links that are actually flagged
282        let warnings = self.check(ctx)?;
283        if warnings.is_empty() {
284            return Ok(content.to_string());
285        }
286
287        // Collect all fixes with their ranges
288        let mut fixes: Vec<(std::ops::Range<usize>, String)> = warnings
289            .iter()
290            .filter_map(|w| w.fix.as_ref().map(|f| (f.range.clone(), f.replacement.clone())))
291            .collect();
292
293        // Sort fixes by position (descending) to apply from end to start
294        fixes.sort_by(|a, b| b.0.start.cmp(&a.0.start));
295
296        let mut result = content.to_string();
297
298        // Apply fixes from end to start to maintain correct positions
299        for (range, replacement) in fixes {
300            result.replace_range(range, &replacement);
301        }
302
303        Ok(result)
304    }
305
306    /// Get the category of this rule for selective processing
307    fn category(&self) -> RuleCategory {
308        RuleCategory::Link
309    }
310
311    /// Check if this rule should be skipped
312    fn should_skip(&self, ctx: &crate::lint_context::LintContext) -> bool {
313        ctx.content.is_empty() || !ctx.likely_has_links_or_images()
314    }
315
316    fn as_any(&self) -> &dyn std::any::Any {
317        self
318    }
319
320    fn from_config(_config: &crate::config::Config) -> Box<dyn Rule>
321    where
322        Self: Sized,
323    {
324        // Flavor is now accessed from LintContext during check
325        Box::new(MD042NoEmptyLinks::new())
326    }
327}
328
329#[cfg(test)]
330mod tests {
331    use super::*;
332    use crate::lint_context::LintContext;
333
334    #[test]
335    fn test_links_with_text_should_pass() {
336        let ctx = LintContext::new(
337            "[valid link](https://example.com)",
338            crate::config::MarkdownFlavor::Standard,
339        );
340        let rule = MD042NoEmptyLinks::new();
341        let result = rule.check(&ctx).unwrap();
342        assert!(result.is_empty(), "Links with text should pass");
343
344        let ctx = LintContext::new(
345            "[another valid link](path/to/page.html)",
346            crate::config::MarkdownFlavor::Standard,
347        );
348        let result = rule.check(&ctx).unwrap();
349        assert!(result.is_empty(), "Links with text and relative URLs should pass");
350    }
351
352    #[test]
353    fn test_links_with_empty_text_should_fail() {
354        let ctx = LintContext::new("[](https://example.com)", crate::config::MarkdownFlavor::Standard);
355        let rule = MD042NoEmptyLinks::new();
356        let result = rule.check(&ctx).unwrap();
357        assert_eq!(result.len(), 1);
358        assert_eq!(result[0].message, "Empty link found: [](https://example.com)");
359        assert_eq!(result[0].line, 1);
360        assert_eq!(result[0].column, 1);
361    }
362
363    #[test]
364    fn test_links_with_only_whitespace_should_fail() {
365        let ctx = LintContext::new("[   ](https://example.com)", crate::config::MarkdownFlavor::Standard);
366        let rule = MD042NoEmptyLinks::new();
367        let result = rule.check(&ctx).unwrap();
368        assert_eq!(result.len(), 1);
369        assert_eq!(result[0].message, "Empty link found: [   ](https://example.com)");
370
371        let ctx = LintContext::new("[\t\n](https://example.com)", crate::config::MarkdownFlavor::Standard);
372        let result = rule.check(&ctx).unwrap();
373        assert_eq!(result.len(), 1);
374        assert_eq!(result[0].message, "Empty link found: [\t\n](https://example.com)");
375    }
376
377    #[test]
378    fn test_reference_links_with_empty_text() {
379        let ctx = LintContext::new(
380            "[][ref]\n\n[ref]: https://example.com",
381            crate::config::MarkdownFlavor::Standard,
382        );
383        let rule = MD042NoEmptyLinks::new();
384        let result = rule.check(&ctx).unwrap();
385        assert_eq!(result.len(), 1);
386        assert_eq!(result[0].message, "Empty link found: [][ref]");
387        assert_eq!(result[0].line, 1);
388
389        // Empty text with empty reference
390        let ctx = LintContext::new(
391            "[][]\n\n[]: https://example.com",
392            crate::config::MarkdownFlavor::Standard,
393        );
394        let result = rule.check(&ctx).unwrap();
395        assert_eq!(result.len(), 1);
396    }
397
398    #[test]
399    fn test_images_should_be_ignored() {
400        // Images can have empty alt text, so they should not trigger the rule
401        let ctx = LintContext::new("![](image.png)", crate::config::MarkdownFlavor::Standard);
402        let rule = MD042NoEmptyLinks::new();
403        let result = rule.check(&ctx).unwrap();
404        assert!(result.is_empty(), "Images with empty alt text should be ignored");
405
406        let ctx = LintContext::new("![   ](image.png)", crate::config::MarkdownFlavor::Standard);
407        let result = rule.check(&ctx).unwrap();
408        assert!(result.is_empty(), "Images with whitespace alt text should be ignored");
409    }
410
411    #[test]
412    fn test_links_with_nested_formatting() {
413        // Links with nested formatting but empty effective text
414        // Note: [**] contains "**" as text, which is not empty after trimming
415        let ctx = LintContext::new("[**](https://example.com)", crate::config::MarkdownFlavor::Standard);
416        let rule = MD042NoEmptyLinks::new();
417        let result = rule.check(&ctx).unwrap();
418        assert!(result.is_empty(), "[**] is not considered empty since ** is text");
419
420        let ctx = LintContext::new("[__](https://example.com)", crate::config::MarkdownFlavor::Standard);
421        let result = rule.check(&ctx).unwrap();
422        assert!(result.is_empty(), "[__] is not considered empty since __ is text");
423
424        // Links with truly empty formatting should fail
425        let ctx = LintContext::new("[](https://example.com)", crate::config::MarkdownFlavor::Standard);
426        let result = rule.check(&ctx).unwrap();
427        assert_eq!(result.len(), 1);
428
429        // Links with nested formatting and actual text should pass
430        let ctx = LintContext::new(
431            "[**bold text**](https://example.com)",
432            crate::config::MarkdownFlavor::Standard,
433        );
434        let result = rule.check(&ctx).unwrap();
435        assert!(result.is_empty(), "Links with nested formatting and text should pass");
436
437        let ctx = LintContext::new(
438            "[*italic* and **bold**](https://example.com)",
439            crate::config::MarkdownFlavor::Standard,
440        );
441        let result = rule.check(&ctx).unwrap();
442        assert!(result.is_empty(), "Links with multiple nested formatting should pass");
443    }
444
445    #[test]
446    fn test_multiple_empty_links_on_same_line() {
447        let ctx = LintContext::new(
448            "[](url1) and [](url2) and [valid](url3)",
449            crate::config::MarkdownFlavor::Standard,
450        );
451        let rule = MD042NoEmptyLinks::new();
452        let result = rule.check(&ctx).unwrap();
453        assert_eq!(result.len(), 2, "Should detect both empty links");
454        assert_eq!(result[0].column, 1);
455        assert_eq!(result[1].column, 14);
456    }
457
458    #[test]
459    fn test_escaped_brackets() {
460        // Escaped brackets should not be treated as links
461        let ctx = LintContext::new("\\[\\](https://example.com)", crate::config::MarkdownFlavor::Standard);
462        let rule = MD042NoEmptyLinks::new();
463        let result = rule.check(&ctx).unwrap();
464        assert!(result.is_empty(), "Escaped brackets should not be treated as links");
465
466        // But this should still be a link
467        let ctx = LintContext::new("[\\[\\]](https://example.com)", crate::config::MarkdownFlavor::Standard);
468        let result = rule.check(&ctx).unwrap();
469        assert!(result.is_empty(), "Link with escaped brackets in text should pass");
470    }
471
472    #[test]
473    fn test_links_in_lists_and_blockquotes() {
474        // Empty links in lists
475        let ctx = LintContext::new(
476            "- [](https://example.com)\n- [valid](https://example.com)",
477            crate::config::MarkdownFlavor::Standard,
478        );
479        let rule = MD042NoEmptyLinks::new();
480        let result = rule.check(&ctx).unwrap();
481        assert_eq!(result.len(), 1);
482        assert_eq!(result[0].line, 1);
483
484        // Empty links in blockquotes
485        let ctx = LintContext::new(
486            "> [](https://example.com)\n> [valid](https://example.com)",
487            crate::config::MarkdownFlavor::Standard,
488        );
489        let result = rule.check(&ctx).unwrap();
490        assert_eq!(result.len(), 1);
491        assert_eq!(result[0].line, 1);
492
493        // Nested structures
494        let ctx = LintContext::new(
495            "> - [](url1)\n> - [text](url2)",
496            crate::config::MarkdownFlavor::Standard,
497        );
498        let result = rule.check(&ctx).unwrap();
499        assert_eq!(result.len(), 1);
500    }
501
502    #[test]
503    fn test_unicode_whitespace_characters() {
504        // Non-breaking space (U+00A0) - IS considered whitespace by Rust's trim()
505        let ctx = LintContext::new(
506            "[\u{00A0}](https://example.com)",
507            crate::config::MarkdownFlavor::Standard,
508        );
509        let rule = MD042NoEmptyLinks::new();
510        let result = rule.check(&ctx).unwrap();
511        assert_eq!(result.len(), 1, "Non-breaking space should be treated as whitespace");
512
513        // Em space (U+2003) - IS considered whitespace by Rust's trim()
514        let ctx = LintContext::new(
515            "[\u{2003}](https://example.com)",
516            crate::config::MarkdownFlavor::Standard,
517        );
518        let result = rule.check(&ctx).unwrap();
519        assert_eq!(result.len(), 1, "Em space should be treated as whitespace");
520
521        // Zero-width space (U+200B) - NOT considered whitespace by Rust's trim()
522        // This is a formatting character, not a whitespace character
523        let ctx = LintContext::new(
524            "[\u{200B}](https://example.com)",
525            crate::config::MarkdownFlavor::Standard,
526        );
527        let result = rule.check(&ctx).unwrap();
528        assert!(
529            result.is_empty(),
530            "Zero-width space is not considered whitespace by trim()"
531        );
532
533        // Test with zero-width space between spaces
534        // Since trim() doesn't consider zero-width space as whitespace,
535        // " \u{200B} " becomes "\u{200B}" after trimming, which is NOT empty
536        let ctx = LintContext::new(
537            "[ \u{200B} ](https://example.com)",
538            crate::config::MarkdownFlavor::Standard,
539        );
540        let result = rule.check(&ctx).unwrap();
541        assert!(
542            result.is_empty(),
543            "Zero-width space remains after trim(), so link is not empty"
544        );
545    }
546
547    #[test]
548    fn test_empty_url_with_text() {
549        let ctx = LintContext::new("[some text]()", crate::config::MarkdownFlavor::Standard);
550        let rule = MD042NoEmptyLinks::new();
551        let result = rule.check(&ctx).unwrap();
552        assert_eq!(result.len(), 1);
553        assert_eq!(result[0].message, "Empty link found: [some text]()");
554    }
555
556    #[test]
557    fn test_both_empty_text_and_url() {
558        let ctx = LintContext::new("[]()", crate::config::MarkdownFlavor::Standard);
559        let rule = MD042NoEmptyLinks::new();
560        let result = rule.check(&ctx).unwrap();
561        assert_eq!(result.len(), 1);
562        assert_eq!(result[0].message, "Empty link found: []()");
563    }
564
565    #[test]
566    fn test_reference_link_with_undefined_reference() {
567        let ctx = LintContext::new("[text][undefined]", crate::config::MarkdownFlavor::Standard);
568        let rule = MD042NoEmptyLinks::new();
569        let result = rule.check(&ctx).unwrap();
570        assert_eq!(result.len(), 1, "Undefined reference should be treated as empty URL");
571    }
572
573    #[test]
574    fn test_shortcut_reference_links() {
575        // Valid shortcut reference link (implicit reference)
576        // Note: [example] by itself is not parsed as a link by the LINK_PATTERN regex
577        // It needs to be followed by [] or () to be recognized as a link
578        let ctx = LintContext::new(
579            "[example][]\n\n[example]: https://example.com",
580            crate::config::MarkdownFlavor::Standard,
581        );
582        let rule = MD042NoEmptyLinks::new();
583        let result = rule.check(&ctx).unwrap();
584        assert!(result.is_empty(), "Valid implicit reference link should pass");
585
586        // Empty implicit reference link
587        let ctx = LintContext::new(
588            "[][]\n\n[]: https://example.com",
589            crate::config::MarkdownFlavor::Standard,
590        );
591        let result = rule.check(&ctx).unwrap();
592        assert_eq!(result.len(), 1, "Empty implicit reference link should fail");
593
594        // Test actual shortcut-style links are not detected (since they don't match the pattern)
595        let ctx = LintContext::new(
596            "[example]\n\n[example]: https://example.com",
597            crate::config::MarkdownFlavor::Standard,
598        );
599        let result = rule.check(&ctx).unwrap();
600        assert!(
601            result.is_empty(),
602            "Shortcut links without [] or () are not parsed as links"
603        );
604    }
605
606    #[test]
607    fn test_fix_suggestions() {
608        let rule = MD042NoEmptyLinks::new();
609
610        // Case 1: Empty text, has URL - fixable (add placeholder text)
611        let ctx = LintContext::new("[](https://example.com)", crate::config::MarkdownFlavor::Standard);
612        let result = rule.check(&ctx).unwrap();
613        assert!(result[0].fix.is_some(), "Empty text with URL should be fixable");
614        let fix = result[0].fix.as_ref().unwrap();
615        assert_eq!(fix.replacement, "[Link text](https://example.com)");
616
617        // Case 2: Non-URL text, empty URL - NOT fixable (can't guess the URL)
618        let ctx = LintContext::new("[text]()", crate::config::MarkdownFlavor::Standard);
619        let result = rule.check(&ctx).unwrap();
620        assert!(
621            result[0].fix.is_none(),
622            "Non-URL text with empty URL should NOT be fixable"
623        );
624
625        // Case 3: URL text, empty URL - fixable (use text as URL)
626        let ctx = LintContext::new("[https://example.com]()", crate::config::MarkdownFlavor::Standard);
627        let result = rule.check(&ctx).unwrap();
628        assert!(result[0].fix.is_some(), "URL text with empty URL should be fixable");
629        let fix = result[0].fix.as_ref().unwrap();
630        assert_eq!(fix.replacement, "[https://example.com](https://example.com)");
631
632        // Case 4: Both empty - NOT fixable (can't guess either)
633        let ctx = LintContext::new("[]()", crate::config::MarkdownFlavor::Standard);
634        let result = rule.check(&ctx).unwrap();
635        assert!(result[0].fix.is_none(), "Both empty should NOT be fixable");
636    }
637
638    #[test]
639    fn test_complex_markdown_document() {
640        let content = r#"# Document with various links
641
642[Valid link](https://example.com) followed by [](empty.com).
643
644## Lists with links
645- [Good link](url1)
646- [](url2)
647- Item with [inline empty]() link
648
649> Quote with [](quoted-empty.com)
650> And [valid quoted](quoted-valid.com)
651
652Code block should be ignored:
653```
654[](this-is-code)
655```
656
657[Reference style][ref1] and [][ref2]
658
659[ref1]: https://ref1.com
660[ref2]: https://ref2.com
661"#;
662
663        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard);
664        let rule = MD042NoEmptyLinks::new();
665        let result = rule.check(&ctx).unwrap();
666
667        // Count the empty links
668        let empty_link_lines = [3, 7, 8, 10, 18];
669        assert_eq!(result.len(), empty_link_lines.len(), "Should find all empty links");
670
671        // Verify line numbers
672        for (i, &expected_line) in empty_link_lines.iter().enumerate() {
673            assert_eq!(
674                result[i].line, expected_line,
675                "Empty link {i} should be on line {expected_line}"
676            );
677        }
678    }
679
680    #[test]
681    fn test_issue_29_code_block_with_tildes() {
682        // Test for issue #29 - code blocks with tilde markers should not break reference links
683        let content = r#"In addition to the [local scope][] and the [global scope][], Python also has a **built-in scope**.
684
685```pycon
686>>> @count_calls
687... def greet(name):
688...     print("Hi", name)
689...
690>>> greet("Trey")
691Traceback (most recent call last):
692  File "<python-input-2>", line 1, in <module>
693    greet("Trey")
694    ~~~~~^^^^^^^^
695  File "<python-input-0>", line 4, in wrapper
696    calls += 1
697    ^^^^^
698UnboundLocalError: cannot access local variable 'calls' where it is not associated with a value
699```
700
701
702[local scope]: https://www.pythonmorsels.com/local-and-global-variables/
703[global scope]: https://www.pythonmorsels.com/assigning-global-variables/"#;
704
705        let ctx = LintContext::new(content, crate::config::MarkdownFlavor::Standard);
706        let rule = MD042NoEmptyLinks::new();
707        let result = rule.check(&ctx).unwrap();
708
709        // These reference links should NOT be flagged as empty
710        assert!(
711            result.is_empty(),
712            "Should not flag reference links as empty when code blocks contain tildes (issue #29). Got: {result:?}"
713        );
714    }
715
716    #[test]
717    fn test_mkdocs_backtick_wrapped_references() {
718        // Test for issue #97 - backtick-wrapped references should be recognized as MkDocs auto-references
719        let rule = MD042NoEmptyLinks::new();
720
721        // Module.Class pattern with backticks
722        let ctx = LintContext::new("[`module.Class`][]", crate::config::MarkdownFlavor::MkDocs);
723        let result = rule.check(&ctx).unwrap();
724        assert!(
725            result.is_empty(),
726            "Should not flag [`module.Class`][] as empty in MkDocs mode (issue #97). Got: {result:?}"
727        );
728
729        // Reference with explicit ID
730        let ctx = LintContext::new("[`module.Class`][ref]", crate::config::MarkdownFlavor::MkDocs);
731        let result = rule.check(&ctx).unwrap();
732        assert!(
733            result.is_empty(),
734            "Should not flag [`module.Class`][ref] as empty in MkDocs mode (issue #97). Got: {result:?}"
735        );
736
737        // Path-like reference with backticks
738        let ctx = LintContext::new("[`api/endpoint`][]", crate::config::MarkdownFlavor::MkDocs);
739        let result = rule.check(&ctx).unwrap();
740        assert!(
741            result.is_empty(),
742            "Should not flag [`api/endpoint`][] as empty in MkDocs mode (issue #97). Got: {result:?}"
743        );
744
745        // Should still flag in standard mode
746        let ctx = LintContext::new("[`module.Class`][]", crate::config::MarkdownFlavor::Standard);
747        let result = rule.check(&ctx).unwrap();
748        assert_eq!(
749            result.len(),
750            1,
751            "Should flag [`module.Class`][] as empty in Standard mode (no auto-refs). Got: {result:?}"
752        );
753
754        // Should still flag truly empty links even in MkDocs mode
755        let ctx = LintContext::new("[][]", crate::config::MarkdownFlavor::MkDocs);
756        let result = rule.check(&ctx).unwrap();
757        assert_eq!(
758            result.len(),
759            1,
760            "Should still flag [][] as empty in MkDocs mode. Got: {result:?}"
761        );
762    }
763}
rumdl_lib/rules/md042_no_empty_links.rs

rumdl_lib/rules/
md042_no_empty_links.rs
