test(mcp): Phase 4 — guard fixture redaction

src/mcp/mod.rs

@@ -772,10 +772,8 @@ mod tests {
 
     #[test]
     fn stdio_recording_fixtures_match_dispatcher() {
-        let fixture_path = std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
-            .join("tests/mcp/fixtures/stdio_smoke.jsonl");
-        let fixture = std::fs::read_to_string(&fixture_path)
-            .unwrap_or_else(|err| panic!("failed to read {}: {err}", fixture_path.display()));
+        let fixture_path = stdio_smoke_fixture_path();
+        let fixture = read_fixture(&fixture_path);
 
         for (line_no, line) in fixture.lines().enumerate() {
             let trimmed = line.trim();
@@ -819,6 +817,47 @@ mod tests {
         }
     }
 
+    #[test]
+    fn stdio_recording_fixtures_are_redacted() {
+        let fixture_path = stdio_smoke_fixture_path();
+        let fixture = read_fixture(&fixture_path);
+        let denied = [
+            "ghp_",
+            "github_pat_",
+            "Bearer ",
+            "Authorization",
+            "/Users/",
+            "/home/",
+            "/var/folders/",
+        ];
+
+        for (line_no, line) in fixture.lines().enumerate() {
+            let trimmed = line.trim();
+            if trimmed.is_empty() || trimmed.starts_with('#') {
+                continue;
+            }
+
+            for pattern in denied {
+                assert!(
+                    !trimmed.contains(pattern),
+                    "fixture line {} contains unredacted pattern '{}'",
+                    line_no + 1,
+                    pattern
+                );
+            }
+        }
+    }
+
+    fn stdio_smoke_fixture_path() -> std::path::PathBuf {
+        std::path::Path::new(env!("CARGO_MANIFEST_DIR"))
+            .join("tests/mcp/fixtures/stdio_smoke.jsonl")
+    }
+
+    fn read_fixture(path: &std::path::Path) -> String {
+        std::fs::read_to_string(path)
+            .unwrap_or_else(|err| panic!("failed to read {}: {err}", path.display()))
+    }
+
     fn assert_fixture_assertion(
         name: &str,
         response: &serde_json::Value,

tests/mcp/README.md

@@ -47,16 +47,16 @@ secret-bearing values with deterministic placeholders.
 | Wall-clock timestamps | `<timestamp>` |
 | Network request IDs | `<request-id>` |
 
-Reviewers should reject fixtures that contain token-shaped strings such as
-`ghp_`, `github_pat_`, `Bearer `, or `Authorization`. Fixture responses should
-also avoid raw stdout/stderr dumps from MCP clients; assert only the stable JSON
-fields needed by the smoke contract.
+The test suite rejects fixtures that contain token-shaped strings such as
+`ghp_`, `github_pat_`, `Bearer `, `Authorization`, or common absolute local
+path prefixes. Fixture responses should also avoid raw stdout/stderr dumps from
+MCP clients; assert only the stable JSON fields needed by the smoke contract.
 
 ## Recording Checklist
 
 1. Capture the smallest request/response pair that exercises the behavior.
 2. Redact secrets, local paths, timestamps, and network-generated IDs.
 3. Prefer `contains_text`, `kind`, `min_len`, and `contains_tool` over copying
    full response payloads.
-4. Run `cargo test --quiet mcp::tests::stdio_recording_fixtures_match_dispatcher`
+4. Run `cargo test --quiet mcp::tests::stdio_recording_fixtures`
    before opening a PR.