@stryker-mutator/core/src/mutants/test-coverage.ts

The extendable JavaScript mutation testing framework

import { CoverageData } from '@stryker-mutator/api/core';
import { Logger } from '@stryker-mutator/api/logging';
import { commonTokens } from '@stryker-mutator/api/plugin';
import { CompleteDryRunResult, TestResult } from '@stryker-mutator/api/test-runner';
import { notEmpty } from '@stryker-mutator/util';

import { coreTokens } from '../di/index.js';

export class TestCoverage {
  readonly #testsByMutantId;
  readonly #testsById;
  readonly #staticCoverage;
  readonly #hitsByMutantId;

  constructor(
    testsByMutantId: Map<string, Set<TestResult>>,
    testsById: Map<string, TestResult>,
    staticCoverage: CoverageData | undefined,
    hitsByMutantId: Map<string, number>,
  ) {
    this.#testsByMutantId = testsByMutantId;
    this.#testsById = testsById;
    this.#staticCoverage = staticCoverage;
    this.#hitsByMutantId = hitsByMutantId;
  }

  public get testsByMutantId(): ReadonlyMap<string, Set<TestResult>> {
    return this.#testsByMutantId;
  }
  public get testsById(): ReadonlyMap<string, TestResult> {
    return this.#testsById;
  }
  public get hitsByMutantId(): ReadonlyMap<string, number> {
    return this.#hitsByMutantId;
  }

  public get hasCoverage(): boolean {
    // Since static coverage should always be reported when coverage analysis succeeded (albeit an empty object),
    // we can use that to determine if there is any coverage at all
    return !!this.#staticCoverage;
  }

  public hasStaticCoverage(mutantId: string): boolean {
    return !!(this.#staticCoverage && this.#staticCoverage[mutantId] > 0);
  }

  public addTest(testResult: TestResult): void {
    this.#testsById.set(testResult.id, testResult);
  }

  public addCoverage(mutantId: string, testIds: string[]): void {
    const tests = this.#testsByMutantId.get(mutantId) ?? new Set();
    this.#testsByMutantId.set(mutantId, tests);
    testIds
      .map((testId) => this.#testsById.get(testId))
      .filter(notEmpty)
      .forEach((test) => tests.add(test));
  }

  public forMutant(mutantId: string): ReadonlySet<TestResult> | undefined {
    return this.#testsByMutantId.get(mutantId);
  }

  public static from = testCoverageFrom;
}

function testCoverageFrom({ tests, mutantCoverage }: CompleteDryRunResult, logger: Logger): TestCoverage {
  const hitsByMutantId = new Map<string, number>();
  const testsByMutantId = new Map<string, Set<TestResult>>();
  const testsById = tests.reduce((acc, test) => acc.set(test.id, test), new Map<string, TestResult>());
  if (mutantCoverage) {
    Object.entries(mutantCoverage.perTest).forEach(([testId, coverage]) => {
      const foundTest = testsById.get(testId);
      if (!foundTest) {
        logger.warn(
          `Found test with id "${testId}" in coverage data, but not in the test results of the dry run. Not taking coverage data for this test into account.`,
        );
        return;
      }
      Object.entries(coverage).forEach(([mutantId, count]) => {
        if (count > 0) {
          let cov = testsByMutantId.get(mutantId);
          if (!cov) {
            cov = new Set();
            testsByMutantId.set(mutantId, cov);
          }
          cov.add(foundTest);
        }
      });
    });

    // We don't care about the exact tests in this case, just the total number of hits
    const coverageResultsPerMutant = [mutantCoverage.static, ...Object.values(mutantCoverage.perTest)];
    coverageResultsPerMutant.forEach((coverageByMutantId) => {
      Object.entries(coverageByMutantId).forEach(([mutantId, count]) => {
        hitsByMutantId.set(mutantId, (hitsByMutantId.get(mutantId) ?? 0) + count);
      });
    });
  }
  return new TestCoverage(testsByMutantId, testsById, mutantCoverage?.static, hitsByMutantId);
}
testCoverageFrom.inject = [coreTokens.dryRunResult, commonTokens.logger] as const;