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>

Author: vsemozhetbyt

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;
 };