test_runner: address review feedback on statement coverage

- lazy-load acorn and acorn-walk behind ??= guard
- fix 100% statement coverage for unparseable files
- sort coverage ranges by startOffset for early loop exit
- regenerate snapshot files from native linux build
- update hardcoded report strings in coverage tests

Author: Felipeness

lib/internal/test_runner/coverage.js

@@ -3,6 +3,7 @@ const {
   ArrayFrom,
   ArrayPrototypeMap,
   ArrayPrototypePush,
+  ArrayPrototypeSort,
   JSONParse,
   MathFloor,
   MathMax,
@@ -30,10 +31,8 @@ const { tmpdir } = require('os');
 const { join, resolve, relative } = require('path');
 const { fileURLToPath, URL } = require('internal/url');
 const { kMappings, SourceMap } = require('internal/source_map/source_map');
-const { Parser: AcornParser } =
-  require('internal/deps/acorn/acorn/dist/acorn');
-const { simple: acornWalkSimple } =
-  require('internal/deps/acorn/acorn-walk/dist/walk');
+let AcornParser;  // Lazy loaded -- only needed when statement coverage is enabled.
+let acornWalkSimple;
 const {
   codes: {
     ERR_SOURCE_MAP_CORRUPT,
@@ -94,6 +93,11 @@ class TestCoverage {
       return null;
     }
 
+    AcornParser ??=
+      require('internal/deps/acorn/acorn/dist/acorn').Parser;
+    acornWalkSimple ??=
+      require('internal/deps/acorn/acorn-walk/dist/walk').simple;
+
     const statements = [];
 
     // Parse as script with permissive flags -- script mode is non-strict,
@@ -333,8 +337,6 @@ class TestCoverage {
       const statementReports = [];
 
       if (statements) {
-        // Flatten all V8 coverage ranges into a single array so
-        // the statement loop only needs two levels of iteration.
         const allRanges = [];
         for (let fi = 0; fi < functions.length; ++fi) {
           const { ranges } = functions[fi];
@@ -343,13 +345,17 @@ class TestCoverage {
           }
         }
 
+        // Sort by startOffset so the inner loop can break early.
+        ArrayPrototypeSort(allRanges, (a, b) => a.startOffset - b.startOffset);
+
         for (let j = 0; j < statements.length; ++j) {
           const stmt = statements[j];
           let bestCount = 0;
           let bestSize = Infinity;
 
           for (let ri = 0; ri < allRanges.length; ++ri) {
             const range = allRanges[ri];
+            if (range.startOffset > stmt.startOffset) break;
             if (doesRangeContainOtherRange(range, stmt)) {
               const size = range.endOffset - range.startOffset;
               if (size < bestSize) {
@@ -378,6 +384,11 @@ class TestCoverage {
         }
       }
 
+      // When the file could not be parsed (statements === null),
+      // report 0% rather than the misleading 100% from toPercentage(0, 0).
+      const coveredStmtPercent = statements != null ?
+        toPercentage(statementsCovered, totalStatements) : 0;
+
       ArrayPrototypePush(coverageSummary.files, {
         __proto__: null,
         path: fileURLToPath(url),
@@ -392,7 +403,7 @@ class TestCoverage {
         coveredLinePercent: toPercentage(coveredCnt, lines.length),
         coveredBranchPercent: toPercentage(branchesCovered, totalBranches),
         coveredFunctionPercent: toPercentage(functionsCovered, totalFunctions),
-        coveredStatementPercent: toPercentage(statementsCovered, totalStatements),
+        coveredStatementPercent: coveredStmtPercent,
         functions: functionReports,
         branches: branchReports,
         lines: lineReports,

test/parallel/test-runner-coverage-default-exclusion.mjs

@@ -34,7 +34,7 @@ describe('test runner coverage default exclusion', skipIfNoInspector, () => {
       '# test                       |         |        |          |         | ',
       '#  not-matching-test-name.js |  100.00 | 100.00 |   100.00 |  100.00 | ',
       '# -------------------------------------------------------------------------------------',
-      '# all files                  |   90.91 |  91.89 |   100.00 |   83.33 | ',
+      '# all files                  |   92.00 |  91.89 |   100.00 |   83.33 | ',
       '# -------------------------------------------------------------------------------------',
       '# end of coverage report',
     ].join('\n');

test/parallel/test-runner-coverage-source-map.js

@@ -83,9 +83,9 @@ describe('Coverage with source maps', async () => {
       '#   test-runner     |         |        |          |         | ',
       '#    source-maps    |         |        |          |         | ',
       '#     line-lengths  |         |        |          |         | ',
-      '#      index.ts     |  100.00 | 100.00 |   100.00 |  100.00 | ',
+      '#      index.ts     |   98.67 | 100.00 |   100.00 |  100.00 | ',
       '# ----------------------------------------------------------------------------',
-      '# all files         |  100.00 | 100.00 |   100.00 |  100.00 | ',
+      '# all files         |   98.67 | 100.00 |   100.00 |  100.00 | ',
       '# ----------------------------------------------------------------------------',
     ]);
 

test/parallel/test-runner-coverage.js

@@ -198,12 +198,12 @@ test('coverage is combined for multiple processes', skipIfNoInspector, () => {
     '# -----------------------------------------------------------------------------',
     '# file           | stmts % | line % | branch % | funcs % | uncovered lines',
     '# -----------------------------------------------------------------------------',
-    '# common.js      |   86.84 |  89.86 |    62.50 |  100.00 | 8 13-14 18 34-35 53',
+    '# common.js      |   89.47 |  89.86 |    62.50 |  100.00 | 8 13-14 18 34-35 53',
     '# first.test.js  |   87.50 |  83.33 |   100.00 |   50.00 | 5-6',
     '# second.test.js |  100.00 | 100.00 |   100.00 |  100.00 | ',
     '# third.test.js  |  100.00 | 100.00 |   100.00 |  100.00 | ',
     '# -----------------------------------------------------------------------------',
-    '# all files      |   91.04 |  92.11 |    72.73 |   88.89 | ',
+    '# all files      |   92.54 |  92.11 |    72.73 |   88.89 | ',
     '# -----------------------------------------------------------------------------',
     '# end of coverage report',
   ].join('\n');