test(coverage): raise coverage gate margin

Cover release and coverage guardrail edge cases so the CI threshold has more stable headroom without weakening enforcement.

Author: AlbinoGeek

src/coverage-threshold.test.ts

@@ -17,9 +17,37 @@ All files                           |   91.05 |   92.03 |
 
     expect(parseAllFilesLineCoverage(output)).toBe(92.03);
   });
+
+  test("returns undefined when Bun output has no all-files coverage row", () => {
+    const output = "160 pass\n0 fail\nRan 160 tests across 11 files.";
+
+    expect(parseAllFilesLineCoverage(output)).toBeUndefined();
+  });
 });
 
 describe("assertCoverageThreshold", () => {
+  test("accepts line coverage at the minimum and reports the passing value", () => {
+    const messages: string[] = [];
+    const originalLog = console.log;
+    console.log = (message?: unknown) => {
+      messages.push(String(message));
+    };
+
+    try {
+      assertCoverageThreshold("All files                           |   91.05 |   80.00 |", 80);
+    } finally {
+      console.log = originalLog;
+    }
+
+    expect(messages).toEqual(["Coverage OK: 80.00%"]);
+  });
+
+  test("throws when no coverage summary is present", () => {
+    expect(() => assertCoverageThreshold("160 pass\n0 fail", 80)).toThrow(
+      "No coverage summary found.",
+    );
+  });
+
   test("throws when line coverage is below the minimum", () => {
     const output = "All files                           |   91.05 |   79.99 |";
 

src/release-sanity.test.ts

@@ -19,6 +19,17 @@ describe("checkReleaseSanity", () => {
     ).toEqual([]);
   });
 
+  test("rejects invalid package versions before checking release files", () => {
+    expect(
+      checkReleaseSanity({
+        packageJson: { ...BASE_PACKAGE, version: "1.2" },
+        changelog: "",
+        githubRef: "refs/tags/v1.2.3",
+        distFiles: ["coverage-threshold.js"],
+      }),
+    ).toEqual(["package.json version must be a valid semver string."]);
+  });
+
   test("reports mismatched tags and missing changelog entries", () => {
     expect(
       checkReleaseSanity({
@@ -50,4 +61,18 @@ describe("checkReleaseSanity", () => {
       }),
     ).toEqual(["dist must not include test-only artifact server/test-harness.js."]);
   });
+
+  test("rejects generated dist artifacts for test and release helper files", () => {
+    expect(
+      checkReleaseSanity({
+        packageJson: BASE_PACKAGE,
+        changelog: "## [1.2.3] — 2026-04-26\n",
+        distFiles: ["server.js", "server.test.js", "coverage-threshold.js", "release-sanity.js"],
+      }),
+    ).toEqual([
+      "dist must not include test-only artifact server.test.js.",
+      "dist must not include test-only artifact coverage-threshold.js.",
+      "dist must not include test-only artifact release-sanity.js.",
+    ]);
+  });
 });