test_runner: calculate executed lines using source map

lib/internal/test_runner/coverage.js

@@ -36,14 +36,14 @@ const kLineSplitRegex = /(?<=\r?\n)/u;
 const kStatusRegex = /\/\* node:coverage (?<status>enable|disable) \*\//;
 
 class CoverageLine {
-  constructor(line, src, startOffset) {
-    const newlineLength =
+  constructor(line, startOffset, src, length = src?.length) {
+    const newlineLength = src == null ? 0 :
       RegExpPrototypeExec(kLineEndingRegex, src)?.[0].length ?? 0;
 
     this.line = line;
     this.src = src;
     this.startOffset = startOffset;
-    this.endOffset = startOffset + src.length - newlineLength;
+    this.endOffset = startOffset + length - newlineLength;
     this.ignore = false;
     this.count = this.startOffset === this.endOffset ? 1 : 0;
   }
@@ -83,7 +83,7 @@ class TestCoverage {
 
     const lines = ArrayPrototypeMap(linesWithBreaks, (line, i) => {
       const startOffset = offset;
-      const coverageLine = new CoverageLine(i + 1, line, startOffset);
+      const coverageLine = new CoverageLine(i + 1, startOffset, line);
 
       offset += line.length;
 
@@ -335,8 +335,13 @@ class TestCoverage {
         newResult.set(url, script);
         continue;
       }
-      const originalLines = this.getLines(url);
       const { data, lineLengths } = sourceMapCache[url];
+      let offset = 0;
+      const executedLines = ArrayPrototypeMap(lineLengths, (length, i) => {
+        const coverageLine = new CoverageLine(i + 1, offset, null, length);
+        offset += length;
+        return coverageLine;
+      });
       if (data.sourcesContent != null) {
         for (let j = 0; j < data.sources.length; ++j) {
           this.getLines(data.sources[j], data.sourcesContent[j]);
@@ -353,7 +358,7 @@ class TestCoverage {
         const newRanges = [];
         for (let k = 0; k < ranges.length; ++k) {
           const { startOffset, endOffset, count } = ranges[k];
-          const { lines } = mapRangeToLines(ranges[k], originalLines);
+          const { lines } = mapRangeToLines(ranges[k], executedLines);
 
           let startEntry = sourceMap
             .findEntry(lines[0].line - 1, MathMax(0, startOffset - lines[0].startOffset));

test/fixtures/test-runner/coverage-loader/hooks.mjs

@@ -1,11 +1,25 @@
-const source = `
+const sources = {
+// Virtual file. Dosen't exist on disk
+  "virtual.js": `
   import { test } from 'node:test';
   test('test', async () => {});
-`;
+`,
+// file with source map. this emulates the behavior of tsx
+  "sum.test.ts": `\
+import{describe,it}from"node:test";import assert from"node:assert";import{sum}from"./sum.ts";describe("sum",()=>{it("should sum two numbers",()=>{assert.deepStrictEqual(sum(1,2),3)});it("should error out if one is not a number",()=>{assert.throws(()=>sum(1,"b"),Error)})});
+
+//# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJtYXBwaW5ncyI6IkFBQUEsT0FBUyxTQUFVLE9BQVUsWUFDN0IsT0FBTyxXQUFZLGNBQ25CLE9BQVMsUUFBVyxRQUVwQixTQUFTLE1BQU8sSUFBTSxDQUNwQixHQUFHLHlCQUEwQixJQUFNLENBQy9CLE9BQU8sZ0JBQWdCLElBQUksRUFBRSxDQUFDLEVBQUcsQ0FBQyxDQUN0QyxDQUFDLEVBRUQsR0FBRywwQ0FBMkMsSUFBTSxDQUNsRCxPQUFPLE9BQU8sSUFBTSxJQUFJLEVBQUcsR0FBRyxFQUFHLEtBQUssQ0FDeEMsQ0FBQyxDQUNILENBQUMiLCJuYW1lcyI6W10sImlnbm9yZUxpc3QiOltdLCJzb3VyY2VzIjpbIi4vc3VtLnRlc3QudHMiXSwic291cmNlc0NvbnRlbnQiOltudWxsXX0=`,
+// file with source map. this emulates the behavior of tsx
+  "sum.ts": `\
+  var __defProp=Object.defineProperty;var __name=(target,value)=>__defProp(target,"name",{value,configurable:true});function sum(...n){if(!n.every(num=>typeof num==="number"))throw new Error("Not a number");return n.reduce((acc,cur)=>acc+cur)}__name(sum,"sum");export{sum};
+
+  //# sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJtYXBwaW5ncyI6ImtIQUFPLFNBQVMsT0FBUSxFQUFHLENBQ3pCLEdBQUksQ0FBQyxFQUFFLE1BQU8sS0FBUSxPQUFPLE1BQVEsUUFBUSxFQUFHLE1BQU0sSUFBSSxNQUFNLGNBQWMsRUFDOUUsT0FBTyxFQUFFLE9BQU8sQ0FBQyxJQUFLLE1BQVEsSUFBTSxHQUFHLENBQ3pDLENBSGdCIiwibmFtZXMiOltdLCJpZ25vcmVMaXN0IjpbXSwic291cmNlcyI6WyIuL3N1bS50cyJdLCJzb3VyY2VzQ29udGVudCI6W251bGxdfQ==`,
+};
 
 export async function load(url, context, nextLoad) {
-  if (url.endsWith('virtual.js')) {
-    return { format: "module", source, shortCircuit: true };
+  const file = url.split('/').at(-1);
+  if (sources[file] !== undefined) {
+    return { format: "module", source: sources[file], shortCircuit: true };
   }
   return nextLoad(url, context);
 }

test/fixtures/test-runner/coverage-loader/sum.test.ts

@@ -0,0 +1,13 @@
+import { describe, it } from 'node:test'
+import assert from 'node:assert'
+import { sum } from './sum'
+
+describe('sum', () => {
+  it('should sum two numbers', () => {
+    assert.deepStrictEqual(sum(1, 2), 3)
+  })
+
+  it('should error out if one is not a number', () => {
+    assert.throws(() => sum(1, 'b'), Error)
+  })
+})

test/fixtures/test-runner/coverage-loader/sum.ts

@@ -0,0 +1,4 @@
+export function sum (...n) {
+  if (!n.every((num) => typeof num === 'number')) throw new Error('Not a number')
+  return n.reduce((acc, cur) => acc + cur)
+}

test/parallel/test-runner-coverage.js

@@ -303,3 +303,35 @@ test('coverage with ESM hook - source irrelevant', skipIfNoInspector, () => {
   assert(result.stdout.toString().includes(report));
   assert.strictEqual(result.status, 0);
 });
+
+test('coverage with ESM hook - source transpiled', skipIfNoInspector, () => {
+  let report = [
+    '# start of coverage report',
+    '# ------------------------------------------------------------------',
+    '# file              | line % | branch % | funcs % | uncovered lines',
+    '# ------------------------------------------------------------------',
+    '# hooks.mjs         | 100.00 |   100.00 |  100.00 | ',
+    '# register-hooks.js | 100.00 |   100.00 |  100.00 | ',
+    '# sum.test.ts       | 100.00 |   100.00 |  100.00 | ',
+    '# sum.ts            | 100.00 |   100.00 |  100.00 | ',
+    '# ------------------------------------------------------------------',
+    '# all files         | 100.00 |   100.00 |  100.00 |',
+    '# ------------------------------------------------------------------',
+    '# end of coverage report',
+  ].join('\n');
+
+  if (common.isWindows) {
+    report = report.replaceAll('/', '\\');
+  }
+
+  const fixture = fixtures.path('test-runner', 'coverage-loader');
+  const args = [
+    '--import', './register-hooks.js', '--test', '--experimental-test-coverage',
+    '--test-reporter', 'tap', 'sum.test.ts',
+  ];
+  const result = spawnSync(process.execPath, args, { cwd: fixture });
+
+  assert.strictEqual(result.stderr.toString(), '');
+  assert(result.stdout.toString().includes(report));
+  assert.strictEqual(result.status, 0);
+});