private _checkThreshold()

in packages/jest-reporters/src/CoverageReporter.ts [229:420]
113 lines of code
17 McCabe index (conditional complexity)

  private _checkThreshold(map: istanbulCoverage.CoverageMap) {
    const {coverageThreshold} = this._globalConfig;

    if (coverageThreshold) {
      function check(
        name: string,
        thresholds: Config.CoverageThresholdValue,
        actuals: istanbulCoverage.CoverageSummaryData,
      ) {
        return (
          ['statements', 'branches', 'lines', 'functions'] as Array<
            keyof istanbulCoverage.CoverageSummaryData
          >
        ).reduce<Array<string>>((errors, key) => {
          const actual = actuals[key].pct;
          const actualUncovered = actuals[key].total - actuals[key].covered;
          const threshold = thresholds[key];

          if (threshold !== undefined) {
            if (threshold < 0) {
              if (threshold * -1 < actualUncovered) {
                errors.push(
                  `Jest: Uncovered count for ${key} (${actualUncovered}) ` +
                    `exceeds ${name} threshold (${-1 * threshold})`,
                );
              }
            } else if (actual < threshold) {
              errors.push(
                `Jest: "${name}" coverage threshold for ${key} (${threshold}%) not met: ${actual}%`,
              );
            }
          }
          return errors;
        }, []);
      }

      const THRESHOLD_GROUP_TYPES = {
        GLOB: 'glob',
        GLOBAL: 'global',
        PATH: 'path',
      };
      const coveredFiles = map.files();
      const thresholdGroups = Object.keys(coverageThreshold);
      const groupTypeByThresholdGroup: {[index: string]: string} = {};
      const filesByGlob: {[index: string]: Array<string>} = {};

      const coveredFilesSortedIntoThresholdGroup = coveredFiles.reduce<
        Array<[string, string | undefined]>
      >((files, file) => {
        const pathOrGlobMatches = thresholdGroups.reduce<
          Array<[string, string]>
        >((agg, thresholdGroup) => {
          const absoluteThresholdGroup = path.resolve(thresholdGroup);

          // The threshold group might be a path:

          if (file.indexOf(absoluteThresholdGroup) === 0) {
            groupTypeByThresholdGroup[thresholdGroup] =
              THRESHOLD_GROUP_TYPES.PATH;
            return agg.concat([[file, thresholdGroup]]);
          }

          // If the threshold group is not a path it might be a glob:

          // Note: glob.sync is slow. By memoizing the files matching each glob
          // (rather than recalculating it for each covered file) we save a tonne
          // of execution time.
          if (filesByGlob[absoluteThresholdGroup] === undefined) {
            filesByGlob[absoluteThresholdGroup] = glob
              .sync(absoluteThresholdGroup)
              .map(filePath => path.resolve(filePath));
          }

          if (filesByGlob[absoluteThresholdGroup].indexOf(file) > -1) {
            groupTypeByThresholdGroup[thresholdGroup] =
              THRESHOLD_GROUP_TYPES.GLOB;
            return agg.concat([[file, thresholdGroup]]);
          }

          return agg;
        }, []);

        if (pathOrGlobMatches.length > 0) {
          return files.concat(pathOrGlobMatches);
        }

        // Neither a glob or a path? Toss it in global if there's a global threshold:
        if (thresholdGroups.indexOf(THRESHOLD_GROUP_TYPES.GLOBAL) > -1) {
          groupTypeByThresholdGroup[THRESHOLD_GROUP_TYPES.GLOBAL] =
            THRESHOLD_GROUP_TYPES.GLOBAL;
          return files.concat([[file, THRESHOLD_GROUP_TYPES.GLOBAL]]);
        }

        // A covered file that doesn't have a threshold:
        return files.concat([[file, undefined]]);
      }, []);

      const getFilesInThresholdGroup = (thresholdGroup: string) =>
        coveredFilesSortedIntoThresholdGroup
          .filter(fileAndGroup => fileAndGroup[1] === thresholdGroup)
          .map(fileAndGroup => fileAndGroup[0]);

      function combineCoverage(filePaths: Array<string>) {
        return filePaths
          .map(filePath => map.fileCoverageFor(filePath))
          .reduce(
            (
              combinedCoverage:
                | istanbulCoverage.CoverageSummary
                | null
                | undefined,
              nextFileCoverage: istanbulCoverage.FileCoverage,
            ) => {
              if (combinedCoverage === undefined || combinedCoverage === null) {
                return nextFileCoverage.toSummary();
              }
              return combinedCoverage.merge(nextFileCoverage.toSummary());
            },
            undefined,
          );
      }

      let errors: Array<string> = [];

      thresholdGroups.forEach(thresholdGroup => {
        switch (groupTypeByThresholdGroup[thresholdGroup]) {
          case THRESHOLD_GROUP_TYPES.GLOBAL: {
            const coverage = combineCoverage(
              getFilesInThresholdGroup(THRESHOLD_GROUP_TYPES.GLOBAL),
            );
            if (coverage) {
              errors = errors.concat(
                check(
                  thresholdGroup,
                  coverageThreshold[thresholdGroup],
                  coverage,
                ),
              );
            }
            break;
          }
          case THRESHOLD_GROUP_TYPES.PATH: {
            const coverage = combineCoverage(
              getFilesInThresholdGroup(thresholdGroup),
            );
            if (coverage) {
              errors = errors.concat(
                check(
                  thresholdGroup,
                  coverageThreshold[thresholdGroup],
                  coverage,
                ),
              );
            }
            break;
          }
          case THRESHOLD_GROUP_TYPES.GLOB:
            getFilesInThresholdGroup(thresholdGroup).forEach(
              fileMatchingGlob => {
                errors = errors.concat(
                  check(
                    fileMatchingGlob,
                    coverageThreshold[thresholdGroup],
                    map.fileCoverageFor(fileMatchingGlob).toSummary(),
                  ),
                );
              },
            );
            break;
          default:
            // If the file specified by path is not found, error is returned.
            if (thresholdGroup !== THRESHOLD_GROUP_TYPES.GLOBAL) {
              errors = errors.concat(
                `Jest: Coverage data for ${thresholdGroup} was not found.`,
              );
            }
          // Sometimes all files in the coverage data are matched by
          // PATH and GLOB threshold groups in which case, don't error when
          // the global threshold group doesn't match any files.
        }
      });

      errors = errors.filter(
        err => err !== undefined && err !== null && err.length > 0,
      );

      if (errors.length > 0) {
        this.log(`${FAIL_COLOR(errors.join('\n'))}`);
        this._setError(new Error(errors.join('\n')));
      }
    }
  }