feat!: remove temp file creation and usage

README.md

@@ -11,6 +11,8 @@ have the code coverage across all testsuites.
 
 This tool will handle this for you.
 
+> See the [Migration Notes](#migrating-notes) below if you are looking to upgrade between major versions.
+
 # Usage
 
 ```bash
@@ -45,3 +47,16 @@ works well for common tools such as [NYC](https://github.com/istanbuljs/nyc) tha
 ```bash
 ./node_modules/.bin/lcov-result-merger 'FILE_PATTERN' ['OUTPUT_FILE'] --prepend-source-files --prepend-path-fix "../src"
 ```
+
+## Migrating Notes
+Additional information about breaking changes.
+
+### Version 6
+- The `--legacy-temp-file` flag has been removed. This means that if your project is expecting an
+  errant `lcov.info` file to be created in the PWD, then it will need to be updated to instead use
+  the output file specified when running the command.
+
+- The internal usage of temp files has also been eliminated. This only effects project that are
+  directly importing the `mergeCoverageReportFiles` or `mergeCoverageReportFilesStream` functions
+  into their own code. Both of these methods now return the merged LCOV content directly, in the
+  form of a string, instead of a path to the temporary file where that content could be read.

bin/lcov-result-merger.js

@@ -1,6 +1,6 @@
 #!/usr/bin/env node
 const fastGlob = require('fast-glob');
-const { copyFile, readFile } = require('node:fs/promises');
+const { writeFile } = require('node:fs/promises');
 const { mergeCoverageReportFiles } = require('../index');
 const yargs = require('yargs/yargs');
 const { hideBin } = require('yargs/helpers');
@@ -37,14 +37,6 @@ 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: [],
@@ -60,11 +52,11 @@ const args = yargs(hideBin(process.argv)).command(
     ignore: args.ignore,
   });
 
-  const tempFilePath = await mergeCoverageReportFiles(files, args);
+  const mergeResults = await mergeCoverageReportFiles(files, args);
 
   if (args.outFile) {
-    await copyFile(tempFilePath, args.outFile);
+    await writeFile(args.outFile, mergeResults, 'utf-8');
   } else {
-    process.stdout.write(await readFile(tempFilePath, 'utf-8'));
+    process.stdout.write(mergeResults + '\n');
   }
 })();

index.d.ts

@@ -5,7 +5,6 @@ type ConfigurationPojo = {
   outFile?: string
   prependSourceFiles?: boolean
   prependPathFix?: string
-  legacyTempFile?: boolean
   ignore?: string[]
 }
 

index.js

@@ -2,11 +2,11 @@
  * LCOV result merger
  *
  * @author Michael Weibel <[email protected]>
- * @copyright 2013-2023 Michael Weibel
+ * @copyright 2013-2024 Michael Weibel
  * @license MIT
  */
 
-const { readFile, writeFile } = require('node:fs/promises');
+const { readFile } = require('node:fs/promises');
 const path = require('node:path');
 const { Transform } = require('node:stream');
 const Configuration = require('./lib/configuration');
@@ -77,7 +77,7 @@ function processFile(sourceDir, data, lcov, config) {
 }
 
 /**
- *
+ * Merge together the LCOV contents of the provided files.
  *
  * @param {string[]} filePaths
  * @param {import("./lib/configuration").ConfigurationPojo} options
@@ -93,18 +93,11 @@ async function mergeCoverageReportFiles(filePaths, options) {
     processFile(path.dirname(filePath), fileContent, report, config);
   }
 
-  const tmpFile = await config.getTempFilePath();
-
-  await writeFile(tmpFile, Buffer.from(report.toString()), {
-    encoding: 'utf-8',
-    flag: 'w+',
-  });
-
-  return tmpFile;
+  return report.toString().trim();
 }
 
 /**
- *
+ * A Stream wrapper for the merge utility.
  */
 class WrappingTransform extends Transform {
   constructor(filePathsOrMergeOptions, mergeOptions) {
@@ -128,13 +121,16 @@ class WrappingTransform extends Transform {
 
   _flush(callback) {
     mergeCoverageReportFiles(this.filePaths, this.mergeOptions).then(
-      (tempFile) => callback(null, tempFile),
+      (fullReport) => callback(null, fullReport.toString().trim()),
       (error) => callback(error)
     );
   }
 }
 
 /**
+ * A variation of the `mergeCoverageReportFiles()` utility that will return a
+ * stream instead of a promise.
+ *
  * @param {string[] | import("./lib/configuration").ConfigurationPojo} [filePathsOrOptions]
  * @param {import("./lib/configuration").ConfigurationPojo} [options]
  *

lib/configuration.js

@@ -1,10 +1,3 @@
-const { join } = require('node:path');
-const { tmpdir } = require('node:os');
-const { mkdtemp } = require('node:fs');
-const { promisify } = require('node:util');
-
-const mkdtempAsync = promisify(mkdtemp);
-
 /**
  * @typedef {Object} ConfigurationPojo
  *
@@ -14,8 +7,6 @@ const mkdtempAsync = promisify(mkdtemp);
  * @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]
  */
 
@@ -67,35 +58,5 @@ 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;
-  }
-
-  /**
-   * @param {string} [fileName="lcov.info"]
-   * @param {string} [prefix="lcov-result-merger"]
-   * @return {Promise<string>}
-   */
-  async getTempFilePath(
-    fileName = 'lcov.info',
-    prefix = 'lcov-result-merger-'
-  ) {
-    const tmpPath = this.legacyTempFile
-      ? ''
-      : await mkdtempAsync(join(tmpdir(), prefix));
-
-    return join(tmpPath, fileName);
   }
 };

test/test-e2e/merge-coverage-report-file-streams-spec.js

@@ -2,14 +2,14 @@
 
 const fastGlob = require('fast-glob');
 const chai = require('chai');
-const { getActual, getExpected } = require('../helpers');
+const { getExpected } = require('../helpers');
 const { mergeCoverageReportFilesStream } = require('../../index.js');
 
 chai.should();
 
 async function testStream(pattern, filePathsOrOptions, options) {
   return new Promise((resolve) => {
-    let tempFilePath;
+    let mergeResult;
 
     const stream = pattern
       ? fastGlob
@@ -19,26 +19,24 @@ async function testStream(pattern, filePathsOrOptions, options) {
 
     stream
       .on('data', (chunk) => {
-        tempFilePath = chunk.toString();
+        mergeResult = chunk.toString();
       })
       .on('end', () => {
-        resolve(tempFilePath);
+        resolve(mergeResult);
       });
   });
 }
 
 describe('mergeCoverageReportFilesStream', function () {
   it('should combine the given records into one', async function () {
-    const output = await testStream('./test/fixtures/basic/*/lcov.info');
-    const actual = await getActual(output);
+    const actual = await testStream('./test/fixtures/basic/*/lcov.info');
     const expect = await getExpected('basic');
 
     return actual.should.equal(expect);
   });
 
   it('should handle a record with : in the name', async function () {
-    const output = await testStream('./test/fixtures/windows/lcov.info');
-    const actual = await getActual(output);
+    const actual = await testStream('./test/fixtures/windows/lcov.info');
     const expect = await getExpected('windows');
 
     return actual.should.equal(expect);
@@ -48,8 +46,7 @@ describe('mergeCoverageReportFilesStream', function () {
     const pattern = './test/fixtures/basic/*/lcov.info';
     const options = { 'prepend-source-files': true, 'prepend-path-fix': '' };
 
-    const output = await testStream(pattern, options);
-    const actual = await getActual(output);
+    const actual = await testStream(pattern, options);
     const expect = await getExpected('prepended');
 
     return actual.should.equal(expect);
@@ -59,8 +56,7 @@ describe('mergeCoverageReportFilesStream', function () {
     const pattern = './test/fixtures/coverage-subfolder/*/coverage/lcov.info';
     const options = { 'prepend-source-files': true };
 
-    const output = await testStream(pattern, options);
-    const actual = await getActual(output);
+    const actual = await testStream(pattern, options);
     const expect = await getExpected('prepended-path-fix');
 
     return actual.should.equal(expect);