test: refactor common.ddCommand()

* Remove different paths for Windows and POSIX.
* Remove fixtures file. Simply run the command immediately/directly.
* Since it is never called with more than one value for kilobytes,
  eliminate that argument.
* Update/simplify tests that use this function. (They no longer need to
  use child_process to run the command.)
* Update documentation.

PR-URL: https://github.com/nodejs/node/pull/23411
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: George Adams <george.adams@uk.ibm.com>

7 files changed, 29 insertions, 72 deletions

diff --git a/test/common/README.md b/test/common/README.md
index c3f2c5f6b8..4d914f4f89 100644
--- a/test/common/README.md
+++ b/test/common/README.md
@@ -52,10 +52,9 @@ symlinks
 ([SeCreateSymbolicLinkPrivilege](https://msdn.microsoft.com/en-us/library/windows/desktop/bb530716(v=vs.85).aspx)).
 On non-Windows platforms, this always returns `true`.
 
-### ddCommand(filename, kilobytes)
-* return [<Object>]
+### ddCommand(filename)
 
-Platform normalizes the `dd` command
+Creates a 10 MB file of all null characters.
 
 ### disableCrashOnUnhandledRejection()
 
diff --git a/test/common/index.js b/test/common/index.js
index 75fe2e1548..492bb2f357 100644
--- a/test/common/index.js
+++ b/test/common/index.js
@@ -28,7 +28,6 @@ const assert = require('assert');
 const os = require('os');
 const { exec, execSync, spawnSync } = require('child_process');
 const util = require('util');
-const { fixturesDir } = require('./fixtures');
 const tmpdir = require('./tmpdir');
 const {
   bits,
@@ -174,13 +173,10 @@ function childShouldThrowAndAbort() {
   });
 }
 
-function ddCommand(filename, kilobytes) {
-  if (isWindows) {
-    const p = path.resolve(fixturesDir, 'create-file.js');
-    return `"${process.argv[0]}" "${p}" "${filename}" ${kilobytes * 1024}`;
-  } else {
-    return `dd if=/dev/zero of="${filename}" bs=1024 count=${kilobytes}`;
-  }
+function ddCommand(filename) {
+  const fd = fs.openSync(filename, 'w');
+  fs.ftruncateSync(fd, 10 * 1024 * 1024);
+  fs.closeSync(fd);
 }
 
 
diff --git a/test/fixtures/create-file.js b/test/fixtures/create-file.js
deleted file mode 100644
index ec0d8243d3..0000000000
--- a/test/fixtures/create-file.js
+++ /dev/null
@@ -1,29 +0,0 @@
-// Copyright Joyent, Inc. and other Node contributors.
-//
-// Permission is hereby granted, free of charge, to any person obtaining a
-// copy of this software and associated documentation files (the
-// "Software"), to deal in the Software without restriction, including
-// without limitation the rights to use, copy, modify, merge, publish,
-// distribute, sublicense, and/or sell copies of the Software, and to permit
-// persons to whom the Software is furnished to do so, subject to the
-// following conditions:
-//
-// The above copyright notice and this permission notice shall be included
-// in all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
-// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
-// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
-// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
-// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
-// USE OR OTHER DEALINGS IN THE SOFTWARE.
-
-const fs = require('fs');
-
-var file_name = process.argv[2];
-var file_size = parseInt(process.argv[3]);
-
-var fd = fs.openSync(file_name, 'w');
-fs.ftruncateSync(fd, file_size);
-fs.closeSync(fd);
diff --git a/test/parallel/test-fs-error-messages.js b/test/parallel/test-fs-error-messages.js
index 4ca9fb2ef9..b0480059ed 100644
--- a/test/parallel/test-fs-error-messages.js
+++ b/test/parallel/test-fs-error-messages.js
@@ -32,7 +32,7 @@ tmpdir.refresh();
 const nonexistentFile = fixtures.path('non-existent');
 const nonexistentDir = fixtures.path('non-existent', 'foo', 'bar');
 const existingFile = fixtures.path('exit.js');
-const existingFile2 = fixtures.path('create-file.js');
+const existingFile2 = fixtures.path('a.js');
 const existingDir = tmpdir.path;
 const existingDir2 = fixtures.path('keys');
 const { COPYFILE_EXCL } = fs.constants;
diff --git a/test/parallel/test-http-chunk-problem.js b/test/parallel/test-http-chunk-problem.js
index f999f055fc..dcc3a9c3fc 100644
--- a/test/parallel/test-http-chunk-problem.js
+++ b/test/parallel/test-http-chunk-problem.js
@@ -63,34 +63,31 @@ function executeRequest(cb) {
 
 tmpdir.refresh();
 
-const ddcmd = common.ddCommand(filename, 10240);
+common.ddCommand(filename);
 
-cp.exec(ddcmd, function(err, stdout, stderr) {
-  assert.ifError(err);
-  server = http.createServer(function(req, res) {
-    res.writeHead(200);
+server = http.createServer(function(req, res) {
+  res.writeHead(200);
 
-    // Create the subprocess
-    const cat = cp.spawn('cat', [filename]);
+  // Create the subprocess
+  const cat = cp.spawn('cat', [filename]);
 
-    // Stream the data through to the response as binary chunks
-    cat.stdout.on('data', (data) => {
-      res.write(data);
-    });
-
-    cat.stdout.on('end', () => res.end());
+  // Stream the data through to the response as binary chunks
+  cat.stdout.on('data', (data) => {
+    res.write(data);
+  });
 
-    // End the response on exit (and log errors)
-    cat.on('exit', (code) => {
-      if (code !== 0) {
-        console.error(`subprocess exited with code ${code}`);
-        process.exit(1);
-      }
-    });
+  cat.stdout.on('end', () => res.end());
 
+  // End the response on exit (and log errors)
+  cat.on('exit', (code) => {
+    if (code !== 0) {
+      console.error(`subprocess exited with code ${code}`);
+      process.exit(1);
+    }
   });
 
-  server.listen(0, () => {
-    executeRequest(() => server.close());
-  });
+});
+
+server.listen(0, () => {
+  executeRequest(() => server.close());
 });
diff --git a/test/parallel/test-pipe-file-to-http.js b/test/parallel/test-pipe-file-to-http.js
index cfe289c30c..70805873f1 100644
--- a/test/parallel/test-pipe-file-to-http.js
+++ b/test/parallel/test-pipe-file-to-http.js
@@ -25,7 +25,6 @@ const assert = require('assert');
 const fs = require('fs');
 const http = require('http');
 const path = require('path');
-const cp = require('child_process');
 
 const tmpdir = require('../common/tmpdir');
 tmpdir.refresh();
@@ -57,12 +56,8 @@ const server = http.createServer(function(req, res) {
 server.listen(0);
 
 server.on('listening', function() {
-  const cmd = common.ddCommand(filename, 10240);
-
-  cp.exec(cmd, function(err) {
-    assert.ifError(err);
-    makeRequest();
-  });
+  common.ddCommand(filename);
+  makeRequest();
 });
 
 function makeRequest() {
diff --git a/test/sequential/test-module-loading.js b/test/sequential/test-module-loading.js
index 42916a7903..0e8aafe51b 100644
--- a/test/sequential/test-module-loading.js
+++ b/test/sequential/test-module-loading.js
@@ -251,7 +251,6 @@ try {
 
   assert.deepStrictEqual(children, {
     'common/index.js': {
-      'common/fixtures.js': {},
       'common/tmpdir.js': {}
     },
     'fixtures/not-main-module.js': {},