Make line coverage follow the innermost JSC block

scripts/build/deps/webkit.ts

@@ -3,7 +3,7 @@
  * for local mode. Override via `--webkit-version=<hash>` to test a branch.
  * From https://github.com/oven-sh/WebKit releases.
  */
-export const WEBKIT_VERSION = "2e2aa2290fac856d6f451ceacb58f7f5b44dd057";
+export const WEBKIT_VERSION = "autobuild-preview-pr-570-ee7526b9";
 
 /**
  * WebKit (JavaScriptCore) — the JS engine.

src/sourcemap_jsc/Cargo.toml

@@ -16,7 +16,6 @@ bun_core.workspace = true
 bun_collections.workspace = true
 bun_io.workspace = true
 bun_jsc.workspace = true
-bun_ast.workspace = true
 bun_options_types.workspace = true
 bun_paths.workspace = true
 # bun_runtime — only used in BakeSourceProvider::get_external_data, which is

test/bundler/bundler_bytecode_portable.test.ts

@@ -454,14 +454,14 @@ describe("bytecode cache portability", () => {
           "js": "50b3e5192dd86a205c73583d585884c1b414467b14db54d03c77d3026bf236ff",
           "jsc": {
             "bytes": 1997464,
-            "sha256": "cf47f5e069b3f20c112160c430a3b18c5ce2d501f1c52525d34dfbd054273cfb",
+            "sha256": "80c9aad9f9890c71ad2cd3c4ee885c5685bd34c60d5c7cb68d730ea5cf04d188",
           },
         },
         "bun build --bytecode --minify features.js": {
           "js": "d30a5febed53e316cc2dd2b076502079e809bb0c201ef1671e9a190ecdcf093d",
           "jsc": {
             "bytes": 46152,
-            "sha256": "7dc5fe8fbfaed3c41d424d2f172efb0efa1be60524ecefcc9d77dfc8088b32af",
+            "sha256": "12ce8293f837e44b614ca61517398aeb110738564a27deffc81b3e83357dc831",
           },
         },
         "bun build --bytecode --minify records.js": {
@@ -517,7 +517,7 @@ describe("bytecode cache portability", () => {
           "js": "493bab674ff49b287f26be3f356a3ad6681afb0c7eeffaa590f10cdcd8b58724",
           "jsc": {
             "bytes": 23772944,
-            "sha256": "c0bb1ca0664a9c7146fadb951e4f6f801811918489f5777fdbbda101a6ffd6c6",
+            "sha256": "741e8c74ce2e1a90a50af63bbcebb9b4a42c4e0937d31bd49f1f418c7c49bdb5",
           },
         },
         "bun build --bytecode lodash/lodash.js": {

test/cli/test/__snapshots__/coverage.test.ts.snap

@@ -3,26 +3,24 @@
 exports[`lcov coverage reporter: lcov-coverage-reporter-output 1`] = `
 "TN:
 SF:demo1.ts
-FNF:1
+FNF:0
 FNH:0
-DA:2,19
-DA:3,16
-DA:4,1
-LF:3
-LH:3
+DA:2,1
+DA:3,1
+LF:2
+LH:2
 end_of_record
 TN:
 SF:demo2.ts
 FNF:2
 FNH:1
-DA:2,28
-DA:4,11
-DA:6,9
+DA:2,1
+DA:4,1
+DA:6,1
 DA:9,0
-DA:10,0
-DA:11,1
-DA:14,9
-LF:7
-LH:5
+DA:11,0
+DA:14,1
+LF:6
+LH:4
 end_of_record"
 `;

test/cli/test/coverage.test.ts

@@ -1,4 +1,4 @@
-import { expect, test } from "bun:test";
+import { describe, expect, test } from "bun:test";
 import { bunEnv, bunExe, normalizeBunSnapshot, tempDir } from "harness";
 import { readFileSync } from "node:fs";
 import path from "path";
@@ -192,8 +192,8 @@ test("should call only some functions", () => {
 ---------------|---------|---------|-------------------
 File           | % Funcs | % Lines | Uncovered Line #s
 ---------------|---------|---------|-------------------
-All files      |   75.00 |   83.33 |
- include-me.ts |   50.00 |   66.67 | 6
+All files      |   75.00 |   75.00 |
+ include-me.ts |   50.00 |   50.00 | 6-7
  test.test.ts  |  100.00 |  100.00 | 
 ---------------|---------|---------|-------------------
 
@@ -385,22 +385,22 @@ test("should call both functions", () => {
 SF:include-me.ts
 FNF:1
 FNH:1
-DA:2,11
-DA:3,17
+DA:2,1
+DA:3,1
 LF:2
 LH:2
 end_of_record
 TN:
 SF:test.test.ts
 FNF:1
 FNH:1
-DA:2,40
-DA:3,41
-DA:4,39
-DA:6,42
-DA:7,39
-DA:8,36
-DA:9,2
+DA:2,1
+DA:3,1
+DA:4,1
+DA:6,1
+DA:7,1
+DA:8,1
+DA:9,1
 LF:7
 LH:7
 end_of_record"
@@ -697,3 +697,186 @@ test("calls second", () => {
   expect(record).toMatch(/FNF:2\nFNH:2\n/);
   expect(exitCode).toBe(0);
 });
+
+// Every executed basic block used to be OR-ed into the line set, and only a
+// never-called function cleared lines afterwards. One executed block that
+// enclosed a dead one then marked the dead one as covered, and a hit count
+// grew by one per byte of executed block on the line. Now the innermost range
+// that contains a line's first significant byte decides the line, the same
+// rule JSC uses in findBasicBlockAtTextOffset.
+async function lineHits(dir: string, subject: string): Promise<Record<number, number>> {
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "test", "--coverage", "--coverage-reporter=lcov", "./run.test.ts"],
+    env: bunEnv,
+    cwd: dir,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+  const [stdout, stderr, exitCode] = await Promise.all([proc.stdout.text(), proc.stderr.text(), proc.exited]);
+  expect(exitCode, stdout + stderr).toBe(0);
+  const lcov = readFileSync(path.join(dir, "coverage", "lcov.info"), "utf-8");
+  const record = lcov.split("end_of_record").find(r => r.includes(`SF:${subject}\n`));
+  expect(record).toBeDefined();
+  const hits: Record<number, number> = {};
+  for (const [, line, count] of record!.matchAll(/^DA:(\d+),(\d+)$/gm)) {
+    hits[Number(line)] = Number(count);
+  }
+  return hits;
+}
+
+const runTest = `import { test } from "bun:test";
+import "./subject";
+test("runs", () => {});
+`;
+
+describe.concurrent("line coverage follows the innermost block", () => {
+  test("a dead method, function and if-body stay uncovered next to a class field", async () => {
+    using dir = tempDir("cov-innermost", {
+      "subject.ts": `export class Foo {
+  x = 1;
+  constructor() {}
+  dead() {
+    return 2;
+  }
+}
+export function neverCalled() {
+  return 3;
+}
+export function loop() {
+  let n = 0;
+  for (let i = 0; i < 5; i++) {
+    n += i;
+  }
+  if (n > 100) {
+    console.log("unreachable");
+  }
+  return n;
+}
+new Foo();
+loop();
+`,
+      "run.test.ts": runTest,
+    });
+    expect(await lineHits(String(dir), "subject.ts")).toEqual({
+      1: 1,
+      2: 1,
+      3: 1,
+      4: 0,
+      5: 0,
+      8: 0,
+      9: 0,
+      11: 1,
+      12: 1,
+      13: 1,
+      14: 5,
+      16: 1,
+      17: 0,
+      19: 1,
+      21: 1,
+      22: 1,
+    });
+  });
+
+  test("a never-called accessor stays uncovered next to a called method", async () => {
+    using dir = tempDir("cov-accessor", {
+      "subject.ts": `export class Foo {
+  m() {
+    return 1;
+  }
+  get g() {
+    return 2;
+  }
+  set s(v) {
+    this.v = v;
+  }
+}
+const f = new Foo();
+f.m();
+`,
+      "run.test.ts": runTest,
+    });
+    expect(await lineHits(String(dir), "subject.ts")).toEqual({
+      1: 1,
+      2: 1,
+      3: 1,
+      5: 0,
+      6: 0,
+      8: 0,
+      9: 0,
+      12: 1,
+      13: 1,
+    });
+  });
+
+  test("code after an await or yield that never resumed is uncovered", async () => {
+    using dir = tempDir("cov-await", {
+      "subject.ts": `export async function suspended() {
+  const p = new Promise(() => {});
+  await p;
+  console.log("never");
+}
+export function* gen() {
+  yield 1;
+  console.log("never");
+}
+export async function skipped(flag: boolean) {
+  flag && await new Promise(() => {});
+  return "ran";
+}
+suspended();
+gen().next();
+skipped(false);
+`,
+      "run.test.ts": runTest,
+    });
+    expect(await lineHits(String(dir), "subject.ts")).toEqual({
+      1: 1,
+      2: 1,
+      3: 1,
+      4: 0,
+      6: 1,
+      7: 1,
+      8: 0,
+      10: 1,
+      11: 1,
+      12: 1,
+      14: 1,
+      15: 1,
+      16: 1,
+    });
+  });
+
+  test("the same lines without a source map", async () => {
+    using dir = tempDir("cov-no-sourcemap", {
+      "bunfig.toml": `[test]
+coverageIgnoreSourcemaps = true
+`,
+      "subject.js": `export class Foo {
+  x = 1;
+  dead() {
+    return 2;
+  }
+}
+export function neverCalled() {
+  return 3;
+}
+if (false) {
+  console.log("dead");
+}
+new Foo();
+`,
+      "run.test.ts": runTest,
+    });
+    expect(await lineHits(String(dir), "subject.js")).toEqual({
+      1: 1,
+      2: 1,
+      3: 0,
+      4: 0,
+      7: 0,
+      8: 0,
+      10: 1,
+      11: 0,
+      13: 1,
+    });
+  });
+});