test(@angular/build): verify coverage ignore comments are preserved during compilation

[clydin]

The underlying Vitest coverage engine depends on specific developer comments like /* istanbul ignore next */ or /* v8 ignore next */ being present in the executing code to accurately isolate unmeasured blocks.

This commit adds strict behavioral tests to assert that the Angular CLI's in-memory compilation pipeline (via esbuild) properly preserves these structural comments and forwards them reliably to Vitest's coverage processing engine.

[gemini-code-assist]

Code Review

This pull request introduces new unit tests to verify that coverage ignore comments (istanbul and v8) are correctly respected during the build process. Additionally, it updates the esbuild configuration to set legalComments to 'inline' when optimization is disabled, ensuring license comments are preserved in the output. I have suggested refactoring the repetitive coverage assertion logic in the new test file into a helper function to improve maintainability.

[gemini-code-assist]

The logic for parsing the coverage report and asserting that no statements are uncovered is duplicated across all test cases in this file. Extracting this into a helper function would improve maintainability and make the tests more concise.

For example, you could define a helper like this inside the describeBuilder block:

async function assertNoUncoveredStatements(contextMessage: string) {
  harness.expectFile('coverage/test/coverage-final.json').toExist();
  const coverageMap = JSON.parse(harness.readFile('coverage/test/coverage-final.json'));
  const appComponentPath = Object.keys(coverageMap).find((p) => p.includes('app.component.ts'));
  expect(appComponentPath).toBeDefined();

  const appComponentCoverage = coverageMap[appComponentPath!];
  const statementCounts = Object.values(appComponentCoverage.s) as number[];
  expect(statementCounts.some((count) => count === 0))
    .withContext(contextMessage)
    .toBeFalse();
}