test: reduce string concatenations

Backport-PR-URL: #13835
PR-URL: #12735
Refs: #12455
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>

test/addons/repl-domain-abort/test.js

@@ -18,7 +18,7 @@ process.on('exit', function() {
 
 const lines = [
   // This line shouldn't cause an assertion error.
-  'require(\'' + buildPath + '\')' +
+  `require('${buildPath}')` +
   // Log output to double check callback ran.
   '.method(function() { console.log(\'cb_ran\'); });',
 ];

test/common/index.js

@@ -90,7 +90,7 @@ exports.refreshTmpDir = function() {
 
 if (process.env.TEST_THREAD_ID) {
   exports.PORT += process.env.TEST_THREAD_ID * 100;
-  exports.tmpDirName += '.' + process.env.TEST_THREAD_ID;
+  exports.tmpDirName += `.${process.env.TEST_THREAD_ID}`;
 }
 exports.tmpDir = path.join(testRoot, exports.tmpDirName);
 
@@ -189,10 +189,10 @@ Object.defineProperty(exports, 'hasFipsCrypto', {
 if (exports.isWindows) {
   exports.PIPE = '\\\\.\\pipe\\libuv-test';
   if (process.env.TEST_THREAD_ID) {
-    exports.PIPE += '.' + process.env.TEST_THREAD_ID;
+    exports.PIPE += `.${process.env.TEST_THREAD_ID}`;
   }
 } else {
-  exports.PIPE = exports.tmpDir + '/test.sock';
+  exports.PIPE = `${exports.tmpDir}/test.sock`;
 }
 
 const ifaces = os.networkInterfaces();
@@ -228,10 +228,9 @@ exports.childShouldThrowAndAbort = function() {
 exports.ddCommand = function(filename, kilobytes) {
   if (exports.isWindows) {
     const p = path.resolve(exports.fixturesDir, 'create-file.js');
-    return '"' + process.argv[0] + '" "' + p + '" "' +
-           filename + '" ' + (kilobytes * 1024);
+    return `"${process.argv[0]}" "${p}" "${filename}" ${kilobytes * 1024}`;
   } else {
-    return 'dd if=/dev/zero of="' + filename + '" bs=1024 count=' + kilobytes;
+    return `dd if=/dev/zero of="${filename}" bs=1024 count=${kilobytes}`;
   }
 };
 
@@ -478,7 +477,7 @@ exports.skip = function(msg) {
 function ArrayStream() {
   this.run = function(data) {
     data.forEach((line) => {
-      this.emit('data', line + '\n');
+      this.emit('data', `${line}\n`);
     });
   };
 }

test/debugger/helper-debugger-repl.js

@@ -13,11 +13,11 @@ let quit;
 
 function startDebugger(scriptToDebug) {
   scriptToDebug = process.env.NODE_DEBUGGER_TEST_SCRIPT ||
-                  common.fixturesDir + '/' + scriptToDebug;
+                  `${common.fixturesDir}/${scriptToDebug}`;
 
-  child = spawn(process.execPath, ['debug', '--port=' + port, scriptToDebug]);
+  child = spawn(process.execPath, ['debug', `--port=${port}`, scriptToDebug]);
 
-  console.error('./node', 'debug', '--port=' + port, scriptToDebug);
+  console.error('./node', 'debug', `--port=${port}`, scriptToDebug);
 
   child.stdout.setEncoding('utf-8');
   child.stdout.on('data', function(data) {
@@ -32,10 +32,10 @@ function startDebugger(scriptToDebug) {
   child.on('line', function(line) {
     line = line.replace(/^(debug> *)+/, '');
     console.log(line);
-    assert.ok(expected.length > 0, 'Got unexpected line: ' + line);
+    assert.ok(expected.length > 0, `Got unexpected line: ${line}`);
 
     const expectedLine = expected[0].lines.shift();
-    assert.ok(line.match(expectedLine) !== null, line + ' != ' + expectedLine);
+    assert.ok(line.match(expectedLine) !== null, `${line} != ${expectedLine}`);
 
     if (expected[0].lines.length === 0) {
       const callback = expected[0].callback;
@@ -62,7 +62,7 @@ function startDebugger(scriptToDebug) {
     console.error('dying badly buffer=%j', buffer);
     let err = 'Timeout';
     if (expected.length > 0 && expected[0].lines) {
-      err = err + '. Expected: ' + expected[0].lines.shift();
+      err = `${err}. Expected: ${expected[0].lines.shift()}`;
     }
 
     child.on('close', function() {
@@ -91,8 +91,8 @@ function startDebugger(scriptToDebug) {
 function addTest(input, output) {
   function next() {
     if (expected.length > 0) {
-      console.log('debug> ' + expected[0].input);
-      child.stdin.write(expected[0].input + '\n');
+      console.log(`debug> ${expected[0].input}`);
+      child.stdin.write(`${expected[0].input}\n`);
 
       if (!expected[0].lines) {
         const callback = expected[0].callback;

test/debugger/test-debugger-repl-utf8.js

@@ -1,6 +1,6 @@
 'use strict';
 const common = require('../common');
-const script = common.fixturesDir + '/breakpoints_utf8.js';
+const script = `${common.fixturesDir}/breakpoints_utf8.js`;
 process.env.NODE_DEBUGGER_TEST_SCRIPT = script;
 
 require('./test-debugger-repl.js');

test/gc/test-http-client-connaborted.js

@@ -16,7 +16,7 @@ let done = 0;
 let count = 0;
 let countGC = 0;
 
-console.log('We should do ' + todo + ' requests');
+console.log(`We should do ${todo} requests`);
 
 const server = http.createServer(serverHandler);
 server.listen(0, getall);

test/gc/test-http-client-onerror.js

@@ -18,7 +18,7 @@ let done = 0;
 let count = 0;
 let countGC = 0;
 
-console.log('We should do ' + todo + ' requests');
+console.log(`We should do ${todo} requests`);
 
 const server = http.createServer(serverHandler);
 server.listen(0, runTest);

test/gc/test-http-client-timeout.js

@@ -20,7 +20,7 @@ let done = 0;
 let count = 0;
 let countGC = 0;
 
-console.log('We should do ' + todo + ' requests');
+console.log(`We should do ${todo} requests`);
 
 const server = http.createServer(serverHandler);
 server.listen(0, getall);

test/gc/test-http-client.js

@@ -16,7 +16,7 @@ let done = 0;
 let count = 0;
 let countGC = 0;
 
-console.log('We should do ' + todo + ' requests');
+console.log(`We should do ${todo} requests`);
 
 const server = http.createServer(serverHandler);
 server.listen(0, getall);

test/gc/test-net-timeout.js

@@ -27,7 +27,7 @@ let done = 0;
 let count = 0;
 let countGC = 0;
 
-console.log('We should do ' + todo + ' requests');
+console.log(`We should do ${todo} requests`);
 
 const server = net.createServer(serverHandler);
 server.listen(0, getall);

test/inspector/inspector-helper.js

@@ -167,13 +167,15 @@ TestSession.prototype.processMessage_ = function(message) {
     assert.strictEqual(id, this.expectedId_);
     this.expectedId_++;
     if (this.responseCheckers_[id]) {
-      assert(message['result'], JSON.stringify(message) + ' (response to ' +
-             JSON.stringify(this.messages_[id]) + ')');
+      const messageJSON = JSON.stringify(message);
+      const idJSON = JSON.stringify(this.messages_[id]);
+      assert(message['result'], `${messageJSON} (response to ${idJSON})`);
       this.responseCheckers_[id](message['result']);
       delete this.responseCheckers_[id];
     }
-    assert(!message['error'], JSON.stringify(message) + ' (replying to ' +
-           JSON.stringify(this.messages_[id]) + ')');
+    const messageJSON = JSON.stringify(message);
+    const idJSON = JSON.stringify(this.messages_[id]);
+    assert(!message['error'], `${messageJSON} (replying to ${idJSON})`);
     delete this.messages_[id];
     if (id === this.lastId_) {
       this.lastMessageResponseCallback_ && this.lastMessageResponseCallback_();
@@ -211,12 +213,8 @@ TestSession.prototype.sendInspectorCommands = function(commands) {
     };
     this.sendAll_(commands, () => {
       timeoutId = setTimeout(() => {
-        let s = '';
-        for (const id in this.messages_) {
-          s += id + ', ';
-        }
-        common.fail('Messages without response: ' +
-                    s.substring(0, s.length - 2));
+        common.fail(`Messages without response: ${
+                    Object.keys(this.messages_).join(', ')}`);
       }, TIMEOUT);
     });
   });
@@ -239,7 +237,7 @@ TestSession.prototype.expectMessages = function(expects) {
   if (!(expects instanceof Array)) expects = [ expects ];
 
   const callback = this.createCallbackWithTimeout_(
-      'Matching response was not received:\n' + expects[0]);
+      `Matching response was not received:\n${expects[0]}`);
   this.messagefilter_ = (message) => {
     if (expects[0](message))
       expects.shift();
@@ -254,7 +252,7 @@ TestSession.prototype.expectMessages = function(expects) {
 TestSession.prototype.expectStderrOutput = function(regexp) {
   this.harness_.addStderrFilter(
       regexp,
-      this.createCallbackWithTimeout_('Timed out waiting for ' + regexp));
+      this.createCallbackWithTimeout_(`Timed out waiting for ${regexp}`));
   return this;
 };
 

test/inspector/test-inspector.js

@@ -18,7 +18,7 @@ function checkVersion(err, response) {
   assert.ifError(err);
   assert.ok(response);
   const expected = {
-    'Browser': 'node.js/' + process.version,
+    'Browser': `node.js/${process.version}`,
     'Protocol-Version': '1.1',
   };
   assert.strictEqual(JSON.stringify(response),
@@ -35,7 +35,7 @@ function expectMainScriptSource(result) {
   const expected = helper.mainScriptSource();
   const source = result['scriptSource'];
   assert(source && (source.includes(expected)),
-         'Script source is wrong: ' + source);
+         `Script source is wrong: ${source}`);
 }
 
 function setupExpectBreakOnLine(line, url, session, scopeIdCallback) {

test/internet/test-dns-cares-domains.js

@@ -21,7 +21,7 @@ methods.forEach(function(method) {
   const d = domain.create();
   d.run(function() {
     dns[method]('google.com', function() {
-      assert.strictEqual(process.domain, d, method + ' retains domain');
+      assert.strictEqual(process.domain, d, `${method} retains domain`);
     });
   });
 });

test/internet/test-dns-ipv6.js

@@ -164,7 +164,7 @@ TEST(function test_lookup_all_ipv6(done) {
 
       ips.forEach((ip) => {
         assert.ok(isIPv6(ip.address),
-                  'Invalid IPv6: ' + ip.address.toString());
+                  `Invalid IPv6: ${ip.address.toString()}`);
         assert.strictEqual(ip.family, 6);
       });
 

test/internet/test-dns.js

@@ -541,7 +541,7 @@ req.oncomplete = function(err, domains) {
 };
 
 process.on('exit', function() {
-  console.log(completed + ' tests completed');
+  console.log(`${completed} tests completed`);
   assert.strictEqual(running, false);
   assert.strictEqual(expected, completed);
   assert.ok(getaddrinfoCallbackCalled);

test/internet/test-tls-add-ca-cert.js

@@ -13,7 +13,7 @@ const fs = require('fs');
 const tls = require('tls');
 
 function filenamePEM(n) {
-  return require('path').join(common.fixturesDir, 'keys', n + '.pem');
+  return require('path').join(common.fixturesDir, 'keys', `${n}.pem`);
 }
 
 function loadPEM(n) {

test/parallel/test-assert.js

@@ -139,7 +139,7 @@ assert.doesNotThrow(makeBlock(a.deepEqual, a1, a2));
 
 // having an identical prototype property
 const nbRoot = {
-  toString: function() { return this.first + ' ' + this.last; }
+  toString: function() { return `${this.first} ${this.last}`; }
 };
 
 function nameBuilder(first, last) {

test/parallel/test-async-wrap-check-providers.js

@@ -91,8 +91,8 @@ process.on('SIGINT', () => process.exit());
 // Run from closed net server above.
 function checkTLS() {
   const options = {
-    key: fs.readFileSync(common.fixturesDir + '/keys/ec-key.pem'),
-    cert: fs.readFileSync(common.fixturesDir + '/keys/ec-cert.pem')
+    key: fs.readFileSync(`${common.fixturesDir}/keys/ec-key.pem`),
+    cert: fs.readFileSync(`${common.fixturesDir}/keys/ec-cert.pem`)
   };
   const server = tls.createServer(options, noop)
     .listen(0, function() {

test/parallel/test-buffer-badhex.js

@@ -44,6 +44,6 @@ const Buffer = require('buffer').Buffer;
   const hex = buf.toString('hex');
   assert.deepStrictEqual(Buffer.from(hex, 'hex'), buf);
 
-  const badHex = hex.slice(0, 256) + 'xx' + hex.slice(256, 510);
+  const badHex = `${hex.slice(0, 256)}xx${hex.slice(256, 510)}`;
   assert.deepStrictEqual(Buffer.from(badHex, 'hex'), buf.slice(0, 128));
 }

test/parallel/test-buffer-includes.js

@@ -199,7 +199,7 @@ const longBufferString = Buffer.from(longString);
 let pattern = 'ABACABADABACABA';
 for (let i = 0; i < longBufferString.length - pattern.length; i += 7) {
   const includes = longBufferString.includes(pattern, i);
-  assert(includes, 'Long ABACABA...-string at index ' + i);
+  assert(includes, `Long ABACABA...-string at index ${i}`);
 }
 assert(longBufferString.includes('AJABACA'), 'Long AJABACA, First J');
 assert(longBufferString.includes('AJABACA', 511), 'Long AJABACA, Second J');

test/parallel/test-buffer-indexof.js

@@ -255,7 +255,7 @@ let pattern = 'ABACABADABACABA';
 for (let i = 0; i < longBufferString.length - pattern.length; i += 7) {
   const index = longBufferString.indexOf(pattern, i);
   assert.strictEqual((i + 15) & ~0xf, index,
-                     'Long ABACABA...-string at index ' + i);
+                     `Long ABACABA...-string at index ${i}`);
 }
 assert.strictEqual(510, longBufferString.indexOf('AJABACA'),
                    'Long AJABACA, First J');

test/parallel/test-child-process-buffering.js

@@ -8,12 +8,12 @@ function pwd(callback) {
 
   child.stdout.setEncoding('utf8');
   child.stdout.on('data', function(s) {
-    console.log('stdout: ' + JSON.stringify(s));
+    console.log(`stdout: ${JSON.stringify(s)}`);
     output += s;
   });
 
   child.on('exit', common.mustCall(function(c) {
-    console.log('exit: ' + c);
+    console.log(`exit: ${c}`);
     assert.strictEqual(0, c);
   }));
 

test/parallel/test-child-process-default-options.js

@@ -18,7 +18,7 @@ let response = '';
 child.stdout.setEncoding('utf8');
 
 child.stdout.on('data', function(chunk) {
-  console.log('stdout: ' + chunk);
+  console.log(`stdout: ${chunk}`);
   response += chunk;
 });
 

test/parallel/test-child-process-double-pipe.js

@@ -35,7 +35,7 @@ if (common.isWindows) {
 
 // pipe echo | grep
 echo.stdout.on('data', function(data) {
-  console.error('grep stdin write ' + data.length);
+  console.error(`grep stdin write ${data.length}`);
   if (!grep.stdin.write(data)) {
     echo.stdout.pause();
   }
@@ -65,7 +65,7 @@ sed.on('exit', function() {
 
 // pipe grep | sed
 grep.stdout.on('data', function(data) {
-  console.error('grep stdout ' + data.length);
+  console.error(`grep stdout ${data.length}`);
   if (!sed.stdin.write(data)) {
     grep.stdout.pause();
   }

test/parallel/test-child-process-env.js

@@ -24,7 +24,7 @@ let response = '';
 child.stdout.setEncoding('utf8');
 
 child.stdout.on('data', function(chunk) {
-  console.log('stdout: ' + chunk);
+  console.log(`stdout: ${chunk}`);
   response += chunk;
 });
 

test/parallel/test-child-process-exec-env.js

@@ -10,9 +10,9 @@ let child;
 function after(err, stdout, stderr) {
   if (err) {
     error_count++;
-    console.log('error!: ' + err.code);
-    console.log('stdout: ' + JSON.stringify(stdout));
-    console.log('stderr: ' + JSON.stringify(stderr));
+    console.log(`error!: ${err.code}`);
+    console.log(`stdout: ${JSON.stringify(stdout)}`);
+    console.log(`stderr: ${JSON.stringify(stderr)}`);
     assert.strictEqual(false, err.killed);
   } else {
     success_count++;

test/parallel/test-child-process-fork-close.js

@@ -3,7 +3,7 @@ const common = require('../common');
 const assert = require('assert');
 const fork = require('child_process').fork;
 
-const cp = fork(common.fixturesDir + '/child-process-message-and-exit.js');
+const cp = fork(`${common.fixturesDir}/child-process-message-and-exit.js`);
 
 let gotMessage = false;
 let gotExit = false;

test/parallel/test-child-process-fork.js

@@ -4,7 +4,7 @@ const assert = require('assert');
 const fork = require('child_process').fork;
 const args = ['foo', 'bar'];
 
-const n = fork(common.fixturesDir + '/child-process-spawn-node.js', args);
+const n = fork(`${common.fixturesDir}/child-process-spawn-node.js`, args);
 assert.deepStrictEqual(args, ['foo', 'bar']);
 
 n.on('message', function(m) {

test/parallel/test-child-process-fork3.js

@@ -2,4 +2,4 @@
 const common = require('../common');
 const child_process = require('child_process');
 
-child_process.fork(common.fixturesDir + '/empty.js'); // should not hang
+child_process.fork(`${common.fixturesDir}/empty.js`); // should not hang