feat!: use host system temp directory for transient lcov.info file

Author: mdeanjones

bin/lcov-result-merger.js

@@ -38,6 +38,14 @@ const args = yargs(hideBin(process.argv)).command(
             'If using --prepend-source-files, this is needed to describe the relative path from the lcov ' +
             'directory to the project root.',
         },
+        'legacy-temp-file': {
+          type: 'boolean',
+          default: false,
+          description:
+            'Prior to version 5, a lcov.info file containing the merged output was created in the ' +
+            "current working directory. The operating system's temporary directory is now used by default, " +
+            'but if you relied on prior behavior then this flag will recreate it.',
+        },
         ignore: {
           type: 'array',
           default: [],

index.js

@@ -9,6 +9,7 @@
 const through = require('through2');
 const fs = require('fs');
 const path = require('path');
+const os = require('os');
 const Configuration = require('./lib/Configuration');
 const FullReport = require('./lib/FullReport');
 
@@ -101,12 +102,18 @@ module.exports = function mergeCoverageReportFiles(options) {
     },
 
     function flush() {
-      fs.writeFileSync('lcov.info', Buffer.from(report.toString()), {
+      const tmpPath = config.legacyTempFile
+        ? ''
+        : fs.mkdtempSync(path.join(os.tmpdir(), 'lcov-result-merger-'));
+
+      const tmpFile = path.join(tmpPath, 'lcov.info');
+
+      fs.writeFileSync(tmpFile, Buffer.from(report.toString()), {
         encoding: 'utf-8',
         flag: 'w+',
       });
 
-      this.push('lcov.info');
+      this.push(tmpFile);
       this.emit('end');
     }
   );

lib/Configuration.js

@@ -7,6 +7,8 @@
  * @property {boolean}  [prepend-source-files=false]
  * @property {string}   [prependPathFix]
  * @property {string}   [prepend-path-fix]
+ * @property {boolean}  [legacyTempFile=false]
+ * @property {boolean}  [legacy-temp-file=false]
  * @property {string[]} [ignore]
  */
 
@@ -58,5 +60,19 @@ module.exports = class Configuration {
         : typeof partial['prepend-path-fix'] === 'string'
         ? partial['prepend-path-fix']
         : '..';
+
+    /**
+     * Prior to version 5, a lcov.info file containing the merged output was created in the
+     * current working directory. The operating system's temporary directory is now used by default,
+     * but if you relied on prior behavior then this flag will recreate it.
+     *
+     * @type {boolean}
+     */
+    this.legacyTempFile =
+      typeof partial.legacyTempFile === 'boolean'
+        ? partial.legacyTempFile
+        : typeof partial['legacy-temp-file'] === 'boolean'
+        ? partial['legacy-temp-file']
+        : false;
   }
 };

test/lcov-result-merger-spec.js

@@ -10,12 +10,18 @@ chai.should();
 describe('lcovResultMerger', function () {
   it('should combine the given records into one', async function () {
     const expected = fs.readFileSync('./test/expected/basic/lcov.info', 'utf8');
+    let tmpFilePath = '';
+
     await new Promise((res) => {
       fg.stream('./test/fixtures/basic/*/lcov.info')
         .pipe(lcovResultMerger())
+        .on('data', (tmpFile) => {
+          tmpFilePath = tmpFile;
+        })
         .on('end', res);
     });
-    const actual = fs.readFileSync('lcov.info', 'utf8');
+
+    const actual = fs.readFileSync(tmpFilePath, 'utf8');
     return actual.should.equal(expected);
   });
 
@@ -38,12 +44,17 @@ describe('lcovResultMerger', function () {
       './test/expected/windows/lcov.info',
       'utf8'
     );
+    let tmpFilePath = '';
+
     await new Promise((res) => {
       fg.stream('./test/fixtures/windows/lcov.info')
         .pipe(lcovResultMerger())
+        .on('data', (tmpFile) => {
+          tmpFilePath = tmpFile;
+        })
         .on('end', res);
     });
-    const actual = fs.readFileSync('lcov.info', 'utf8');
+    const actual = fs.readFileSync(tmpFilePath, 'utf8');
     return actual.should.equal(expected);
   });
 
@@ -52,6 +63,9 @@ describe('lcovResultMerger', function () {
       './test/expected/prepended/lcov.info',
       'utf8'
     );
+
+    let tmpFilePath = '';
+
     await new Promise((res) => {
       fg.stream('./test/fixtures/basic/*/lcov.info')
         .pipe(
@@ -60,9 +74,12 @@ describe('lcovResultMerger', function () {
             'prepend-path-fix': '',
           })
         )
+        .on('data', (tmpFile) => {
+          tmpFilePath = tmpFile;
+        })
         .on('end', res);
     });
-    const actual = fs.readFileSync('lcov.info', 'utf8');
+    const actual = fs.readFileSync(tmpFilePath, 'utf8');
     return actual.should.equal(expected);
   });
 
@@ -71,12 +88,18 @@ describe('lcovResultMerger', function () {
       './test/expected/prepended-path-fix/lcov.info',
       'utf8'
     );
+
+    let tmpFilePath = '';
+
     await new Promise((res) => {
       fg.stream('./test/fixtures/coverage-subfolder/*/coverage/lcov.info')
         .pipe(lcovResultMerger({ 'prepend-source-files': true }))
+        .on('data', (tmpFile) => {
+          tmpFilePath = tmpFile;
+        })
         .on('end', res);
     });
-    const actual = fs.readFileSync('lcov.info', 'utf8');
+    const actual = fs.readFileSync(tmpFilePath, 'utf8');
     return actual.should.equal(expected);
   });
 });