story-kit: merge 171_story_persist_test_results_to_story_files

server/src/io/story_metadata.rs

@@ -1,8 +1,11 @@
 use serde::Deserialize;
+use std::fs;
+use std::path::Path;
 
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
 pub struct StoryMetadata {
     pub name: Option<String>,
+    pub coverage_baseline: Option<String>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -23,6 +26,7 @@ impl std::fmt::Display for StoryMetaError {
 #[derive(Debug, Deserialize)]
 struct FrontMatter {
     name: Option<String>,
+    coverage_baseline: Option<String>,
 }
 
 pub fn parse_front_matter(contents: &str) -> Result<StoryMetadata, StoryMetaError> {
@@ -53,9 +57,58 @@ pub fn parse_front_matter(contents: &str) -> Result<StoryMetadata, StoryMetaErro
 fn build_metadata(front: FrontMatter) -> StoryMetadata {
     StoryMetadata {
         name: front.name,
+        coverage_baseline: front.coverage_baseline,
     }
 }
 
+/// Write or update a `coverage_baseline:` field in the YAML front matter of a story file.
+///
+/// If front matter is present, adds or replaces `coverage_baseline:` before the closing `---`.
+/// If no front matter is present, this is a no-op (returns Ok).
+pub fn write_coverage_baseline(path: &Path, coverage_pct: f64) -> Result<(), String> {
+    let contents =
+        fs::read_to_string(path).map_err(|e| format!("Failed to read story file: {e}"))?;
+
+    let updated = set_front_matter_field(&contents, "coverage_baseline", &format!("{coverage_pct:.1}%"));
+    fs::write(path, &updated).map_err(|e| format!("Failed to write story file: {e}"))?;
+    Ok(())
+}
+
+/// Insert or update a key: value pair in the YAML front matter of a markdown string.
+///
+/// If no front matter (opening `---`) is found, returns the content unchanged.
+fn set_front_matter_field(contents: &str, key: &str, value: &str) -> String {
+    let mut lines: Vec<String> = contents.lines().map(String::from).collect();
+    if lines.is_empty() || lines[0].trim() != "---" {
+        return contents.to_string();
+    }
+
+    // Find closing --- (search from index 1)
+    let close_idx = match lines[1..].iter().position(|l| l.trim() == "---") {
+        Some(i) => i + 1,
+        None => return contents.to_string(),
+    };
+
+    let key_prefix = format!("{key}:");
+    let existing_idx = lines[1..close_idx]
+        .iter()
+        .position(|l| l.trim_start().starts_with(&key_prefix))
+        .map(|i| i + 1);
+
+    let new_line = format!("{key}: {value}");
+    if let Some(idx) = existing_idx {
+        lines[idx] = new_line;
+    } else {
+        lines.insert(close_idx, new_line);
+    }
+
+    let mut result = lines.join("\n");
+    if contents.ends_with('\n') {
+        result.push('\n');
+    }
+    result
+}
+
 pub fn parse_unchecked_todos(contents: &str) -> Vec<String> {
     contents
         .lines()
@@ -82,12 +135,49 @@ workflow: tdd
 "#;
 
         let meta = parse_front_matter(input).expect("front matter");
-        assert_eq!(
-            meta,
-            StoryMetadata {
-                name: Some("Establish the TDD Workflow and Gates".to_string()),
-            }
-        );
+        assert_eq!(meta.name.as_deref(), Some("Establish the TDD Workflow and Gates"));
+        assert_eq!(meta.coverage_baseline, None);
+    }
+
+    #[test]
+    fn parses_coverage_baseline_from_front_matter() {
+        let input = "---\nname: Test Story\ncoverage_baseline: 78.5%\n---\n# Story\n";
+        let meta = parse_front_matter(input).expect("front matter");
+        assert_eq!(meta.coverage_baseline.as_deref(), Some("78.5%"));
+    }
+
+    #[test]
+    fn set_front_matter_field_inserts_new_key() {
+        let input = "---\nname: My Story\n---\n# Body\n";
+        let output = set_front_matter_field(input, "coverage_baseline", "55.0%");
+        assert!(output.contains("coverage_baseline: 55.0%"));
+        assert!(output.contains("name: My Story"));
+        assert!(output.ends_with('\n'));
+    }
+
+    #[test]
+    fn set_front_matter_field_updates_existing_key() {
+        let input = "---\nname: My Story\ncoverage_baseline: 40.0%\n---\n# Body\n";
+        let output = set_front_matter_field(input, "coverage_baseline", "55.0%");
+        assert!(output.contains("coverage_baseline: 55.0%"));
+        assert!(!output.contains("40.0%"));
+    }
+
+    #[test]
+    fn set_front_matter_field_no_op_without_front_matter() {
+        let input = "# No front matter\n";
+        let output = set_front_matter_field(input, "coverage_baseline", "55.0%");
+        assert_eq!(output, input);
+    }
+
+    #[test]
+    fn write_coverage_baseline_updates_file() {
+        let tmp = tempfile::tempdir().unwrap();
+        let path = tmp.path().join("story.md");
+        std::fs::write(&path, "---\nname: Test\n---\n# Story\n").unwrap();
+        write_coverage_baseline(&path, 82.3).unwrap();
+        let contents = std::fs::read_to_string(&path).unwrap();
+        assert!(contents.contains("coverage_baseline: 82.3%"));
     }
 
     #[test]