Add support for LCOV report format

README.md

@@ -6,8 +6,8 @@
 ![tests](https://img.shields.io/endpoint?style=flat-square&url=https%3A%2F%2Fgist.githubusercontent.com%2FGaelGirodon%2F715c62717519f634185af0ebde234992%2Fraw%2Fci-badges-action-junit-tests.json)
 ![coverage](https://img.shields.io/endpoint?style=flat-square&url=https%3A%2F%2Fgist.githubusercontent.com%2FGaelGirodon%2F715c62717519f634185af0ebde234992%2Fraw%2Fci-badges-action-cobertura-coverage.json)
 
-This action generates badges (as JSON files) from Go, JUnit, Cobertura and
-JaCoCo test and coverage reports (most test runners and code coverage tools,
+This action generates badges (as JSON files) from Go, JUnit, Cobertura, JaCoCo
+and LCOV test and coverage reports (most test runners and code coverage tools,
 including Mocha, Jest, PHPUnit, c8, Istanbul/nyc, and more, support at least
 one of these formats) and upload them to a Gist to make them available to
 Shields through the endpoint feature with (almost) zero configuration.
@@ -69,6 +69,7 @@ from test report(s).
 ![coverage](https://img.shields.io/endpoint?style=flat-square&url=https%3A%2F%2Fgist.githubusercontent.com%2FGaelGirodon%2F715c62717519f634185af0ebde234992%2Fraw%2Frepo-go-coverage.json)
 ![coverage](https://img.shields.io/endpoint?style=flat-square&url=https%3A%2F%2Fgist.githubusercontent.com%2FGaelGirodon%2F715c62717519f634185af0ebde234992%2Fraw%2Frepo-cobertura-coverage.json)
 ![coverage](https://img.shields.io/endpoint?style=flat-square&url=https%3A%2F%2Fgist.githubusercontent.com%2FGaelGirodon%2F715c62717519f634185af0ebde234992%2Fraw%2Frepo-jacoco-coverage.json)
+![coverage](https://img.shields.io/endpoint?style=flat-square&url=https%3A%2F%2Fgist.githubusercontent.com%2FGaelGirodon%2F715c62717519f634185af0ebde234992%2Fraw%2Frepo-lcov-coverage.json)
 
 This badge displays the percentage of covered lines extracted from a coverage
 report.
@@ -157,6 +158,24 @@ from the first matching and valid report file.
 
 ➡️ `{repo}-[{ref}-]jacoco-coverage.json`
 
+### LCOV
+
+Write the coverage report to a file matching:
+
+- `**/lcov.*`
+- `**/*.lcov`
+
+This is the default format and location with LCOV, but some code coverage
+tools support this format too, natively or using an additional reporter:
+
+- **c8**: `c8 --reporter lcov [...]` → `coverage/lcov.info`
+- **Deno**: `deno test --coverage=cov_profile && deno coverage cov_profile --lcov --output=cov_profile.lcov`
+
+The coverage will be computed using `LF` and `LH` keys, from the first
+matching and valid report file.
+
+➡️ `{repo}-[{ref}-]lcov-coverage.json`
+
 ## Notes
 
 Storing badge JSON files on a Gist may seem tedious, but:

src/reports/index.js

@@ -3,12 +3,13 @@ import * as go from './go.js';
 import * as junit from './junit.js';
 import * as cobertura from './cobertura.js';
 import * as jacoco from './jacoco.js';
+import * as lcov from './lcov.js';
 
 /**
  * Available report loaders
  * @type {{ [key: string]: { getReports: ReportsLoader } }}
  */
-const loaders = { go, junit, cobertura, jacoco };
+const loaders = { go, junit, cobertura, jacoco, lcov };
 
 /**
  * Load all available reports in the current workspace.

src/reports/lcov.js

@@ -0,0 +1,64 @@
+import * as core from '@actions/core';
+import { promises as fs } from 'fs';
+import { join } from 'path';
+import { globNearest } from '../util/index.js';
+
+/**
+ * Load coverage reports using LCOV format.
+ * @param {string} root Root search directory
+ * @returns LCOV coverage report
+ */
+export async function getReports(root) {
+  core.info('Load LCOV coverage report');
+  const patterns = [
+    join(root, '**/lcov.*'),
+    join(root, '**/*.lcov')
+  ];
+  const files = await globNearest(patterns);
+  /** @type {Omit<CoverageReport, 'format'>[]} */
+  const reports = [];
+  for (const f of files) {
+    core.info(`Load LCOV report '${f}'`);
+    const coverage = await getCoverage(f);
+    if (coverage < 0) {
+      core.info('Report is not a valid LCOV report');
+      continue; // Invalid report file, trying the next one
+    }
+    reports.push({ type: 'coverage', data: { coverage } });
+    break; // Successfully loaded a report file, can return now
+  }
+  core.info(`Loaded ${reports.length} LCOV report(s)`);
+  return reports;
+}
+
+/**
+ * Compute the total line coverage rate from the given LCOV report file,
+ * i.e., the ratio of all hit (LH) to found (LF) lines, deduplicated by source
+ * file (SF) (only the best coverage for each source file is considered).
+ * @param {string} path Path to the LCOV coverage report file
+ * @returns {Promise<number>} The total line coverage rate (%),
+ * or -1 if no coverage data can be read from this file
+ */
+async function getCoverage(path) {
+  const contents = await fs.readFile(path, { encoding: 'utf8' });
+  /** @type {{ [sf: string]: { lh: number, lf: number } }} */
+  const sourceFiles = {};
+  let from = 0, to = 0;
+  while ((to = contents.indexOf('end_of_record', from)) > 0) {
+    const record = contents.slice(from, to);
+    const sf = record.match(/^SF:(.+)$/m)?.[1] ?? '';
+    const lh = parseInt(record.match(/^LH:([0-9]+)$/m)?.[1] ?? '0');
+    const lf = parseInt(record.match(/^LF:([0-9]+)$/m)?.[1] ?? '0');
+    const value = sourceFiles[sf];
+    if (sf && (!value || (lf >= value.lf && lh / lf > value.lh / value.lf))) {
+      sourceFiles[sf] = { lh, lf };
+    }
+    from = to + 13;
+  }
+  const { lh, lf } = Object.values(sourceFiles)
+    .reduce((sum, val) => ({
+      lh: sum.lh + val.lh,
+      lf: sum.lf + val.lf
+    }), { lh: 0, lf: 0 });
+  return lf > 0 ? (lh / lf) * 100 : -1;
+}

src/reports/lcov.test.js

@@ -0,0 +1,15 @@
+import assert from 'assert/strict';
+import { join } from 'path';
+import { getReports } from './lcov.js';
+
+describe('reports/lcov', () => {
+  describe('#getReports()', () => {
+    it('should return a coverage report', async () => {
+      const reports = await getReports(join(process.cwd(), 'test/data/lcov'));
+      assert.equal(reports.length, 1);
+      assert.deepEqual(reports, [
+        { type: 'coverage', data: { coverage: 47 } }
+      ]);
+    });
+  });
+});

test/data/lcov/lcov.info

@@ -0,0 +1,22 @@
+TN:
+SF:a.js
+LH:20
+LF:40
+end_of_record
+SF:b.js
+LH:30
+LF:70
+end_of_record
+SF:c.js
+LH:30
+LF:90
+end_of_record
+TN:
+SF:a.js
+LH:34
+LF:40
+end_of_record
+SF:b.js
+LH:20
+LF:70
+end_of_record

test/e2e.test.js

@@ -32,7 +32,8 @@ describe('CI Badges action', function () {
         'repo-go-coverage.json',
         'repo-go-tests.json',
         'repo-jacoco-coverage.json',
-        'repo-junit-tests.json'
+        'repo-junit-tests.json',
+        'repo-lcov-coverage.json'
       ].forEach(f => assert.ok(files.includes(f)));
     });
   });