test: fix RegExp nits

* Remove needless RegExp flag

  In fixed case, `/g` flag is needless in the boolean context.

* Remove needless RegExp capturing

  Use non-capturing grouping or remove capturing completely when:

  * capturing is useless per se, e.g. in test() check;
  * captured groups are not used afterward at all;
  * some of the later captured groups are not used afterward.

* Use test, not match/exec in boolean context

  match() and exec() return a complicated object,
  unneeded in a boolean context.

* Do not needlessly repeat RegExp creation

  This commit takes RegExp creation out of cycles and other repetitions.

  As long as the RegExp does not use /g flag and match indices,
  we are safe here.

  In tests, this fix hardly gives a significant performance gain,
  but it increases clarity and maintainability,
  reassuring some RegExps to be identical.

  RegExp in functions are not taken out of their functions:
  while these functions are called many times
  and their RegExps are recreated with each call,
  the performance gain in test cases
  does not seem to be worth decreasing function self-dependency.

Backport-PR-URL: #14370
PR-URL: #13770
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/common/index.js

@@ -196,8 +196,9 @@ if (exports.isWindows) {
 }
 
 const ifaces = os.networkInterfaces();
+const re = /lo/;
 exports.hasIPv6 = Object.keys(ifaces).some(function(name) {
-  return /lo/.test(name) && ifaces[name].some(function(info) {
+  return re.test(name) && ifaces[name].some(function(info) {
     return info.family === 'IPv6';
   });
 });

test/debugger/helper-debugger-repl.js

@@ -30,12 +30,12 @@ function startDebugger(scriptToDebug) {
   child.stderr.pipe(process.stderr);
 
   child.on('line', function(line) {
-    line = line.replace(/^(debug> *)+/, '');
+    line = line.replace(/^(?:debug> *)+/, '');
     console.log(line);
     assert.ok(expected.length > 0, `Got unexpected line: ${line}`);
 
     const expectedLine = expected[0].lines.shift();
-    assert.ok(line.match(expectedLine) !== null, `${line} != ${expectedLine}`);
+    assert.ok(expectedLine.test(line), `${line} != ${expectedLine}`);
 
     if (expected[0].lines.length === 0) {
       const callback = expected[0].callback;

test/doctool/test-doctool-html.js

@@ -80,9 +80,11 @@ const testData = [
   },
 ];
 
+const spaces = /\s/g;
+
 testData.forEach((item) => {
   // Normalize expected data by stripping whitespace
-  const expected = item.html.replace(/\s/g, '');
+  const expected = item.html.replace(spaces, '');
   const includeAnalytics = typeof item.analyticsId !== 'undefined';
 
   fs.readFile(item.file, 'utf8', common.mustCall((err, input) => {
@@ -101,7 +103,7 @@ testData.forEach((item) => {
         common.mustCall((err, output) => {
           assert.ifError(err);
 
-          const actual = output.replace(/\s/g, '');
+          const actual = output.replace(spaces, '');
           // Assert that the input stripped of all whitespace contains the
           // expected list
           assert.notStrictEqual(actual.indexOf(expected), -1);

test/inspector/test-inspector.js

@@ -10,8 +10,8 @@ function checkListResponse(err, response) {
   assert.strictEqual(1, response.length);
   assert.ok(response[0]['devtoolsFrontendUrl']);
   assert.ok(
-    response[0]['webSocketDebuggerUrl']
-      .match(/ws:\/\/127.0.0.1:\d+\/[0-9A-Fa-f]{8}-/));
+    /ws:\/\/127.0.0.1:\d+\/[0-9A-Fa-f]{8}-/
+      .test(response[0]['webSocketDebuggerUrl']));
 }
 
 function checkVersion(err, response) {

test/parallel/test-buffer-prototype-inspect.js

@@ -19,5 +19,5 @@ const util = require('util');
 
 {
   const buf = Buffer.from('x'.repeat(51));
-  assert.ok(/^<Buffer (78 ){50}\.\.\. >$/.test(util.inspect(buf)));
+  assert.ok(/^<Buffer (?:78 ){50}\.\.\. >$/.test(util.inspect(buf)));
 }

test/parallel/test-cli-syntax.js

@@ -13,6 +13,9 @@ const syntaxArgs = [
   ['--check']
 ];
 
+const syntaxErrorRE = /^SyntaxError: Unexpected identifier$/m;
+const notFoundRE = /^Error: Cannot find module/m;
+
 // test good syntax with and without shebang
 [
   'syntax/good_syntax.js',
@@ -53,8 +56,7 @@ const syntaxArgs = [
     assert.strictEqual(c.stdout, '', 'stdout produced');
 
     // stderr should have a syntax error message
-    const match = c.stderr.match(/^SyntaxError: Unexpected identifier$/m);
-    assert(match, 'stderr incorrect');
+    assert(syntaxErrorRE.test(c.stderr), 'stderr incorrect');
 
     assert.strictEqual(c.status, 1, `code == ${c.status}`);
   });
@@ -76,8 +78,7 @@ const syntaxArgs = [
     assert.strictEqual(c.stdout, '', 'stdout produced');
 
     // stderr should have a module not found error message
-    const match = c.stderr.match(/^Error: Cannot find module/m);
-    assert(match, 'stderr incorrect');
+    assert(notFoundRE.test(c.stderr), 'stderr incorrect');
 
     assert.strictEqual(c.status, 1, `code == ${c.status}`);
   });

test/parallel/test-crypto-authenticated.js

@@ -307,6 +307,13 @@ const TEST_CASES = [
     tag: 'a44a8266ee1c8eb0c8b5d4cf5ae9f19a', tampered: false },
 ];
 
+const errMessages = {
+  auth: / auth/,
+  state: / state/,
+  FIPS: /not supported in FIPS mode/,
+  length: /Invalid IV length/,
+};
+
 const ciphers = crypto.getCiphers();
 
 for (const i in TEST_CASES) {
@@ -357,14 +364,14 @@ for (const i in TEST_CASES) {
       assert.strictEqual(msg, test.plain);
     } else {
       // assert that final throws if input data could not be verified!
-      assert.throws(function() { decrypt.final('ascii'); }, / auth/);
+      assert.throws(function() { decrypt.final('ascii'); }, errMessages.auth);
     }
   }
 
   if (test.password) {
     if (common.hasFipsCrypto) {
       assert.throws(() => { crypto.createCipher(test.algo, test.password); },
-                    /not supported in FIPS mode/);
+                    errMessages.FIPS);
     } else {
       const encrypt = crypto.createCipher(test.algo, test.password);
       if (test.aad)
@@ -383,7 +390,7 @@ for (const i in TEST_CASES) {
   if (test.password) {
     if (common.hasFipsCrypto) {
       assert.throws(() => { crypto.createDecipher(test.algo, test.password); },
-                    /not supported in FIPS mode/);
+                    errMessages.FIPS);
     } else {
       const decrypt = crypto.createDecipher(test.algo, test.password);
       decrypt.setAuthTag(Buffer.from(test.tag, 'hex'));
@@ -395,7 +402,7 @@ for (const i in TEST_CASES) {
         assert.strictEqual(msg, test.plain);
       } else {
         // assert that final throws if input data could not be verified!
-        assert.throws(function() { decrypt.final('ascii'); }, / auth/);
+        assert.throws(function() { decrypt.final('ascii'); }, errMessages.auth);
       }
     }
   }
@@ -406,7 +413,7 @@ for (const i in TEST_CASES) {
                                           Buffer.from(test.key, 'hex'),
                                           Buffer.from(test.iv, 'hex'));
     encrypt.update('blah', 'ascii');
-    assert.throws(function() { encrypt.getAuthTag(); }, / state/);
+    assert.throws(function() { encrypt.getAuthTag(); }, errMessages.state);
   }
 
   {
@@ -415,15 +422,15 @@ for (const i in TEST_CASES) {
                                           Buffer.from(test.key, 'hex'),
                                           Buffer.from(test.iv, 'hex'));
     assert.throws(() => { encrypt.setAuthTag(Buffer.from(test.tag, 'hex')); },
-                  / state/);
+                  errMessages.state);
   }
 
   {
     // trying to read tag from decryption object:
     const decrypt = crypto.createDecipheriv(test.algo,
                                             Buffer.from(test.key, 'hex'),
                                             Buffer.from(test.iv, 'hex'));
-    assert.throws(function() { decrypt.getAuthTag(); }, / state/);
+    assert.throws(function() { decrypt.getAuthTag(); }, errMessages.state);
   }
 
   {
@@ -434,7 +441,7 @@ for (const i in TEST_CASES) {
         Buffer.from(test.key, 'hex'),
         Buffer.alloc(0)
       );
-    }, /Invalid IV length/);
+    }, errMessages.length);
   }
 }
 
@@ -446,6 +453,7 @@ for (const i in TEST_CASES) {
                             '6fKjEjR3Vl30EUYC');
   encrypt.update('blah', 'ascii');
   encrypt.final();
-  assert.throws(() => encrypt.getAuthTag(), / state/);
-  assert.throws(() => encrypt.setAAD(Buffer.from('123', 'ascii')), / state/);
+  assert.throws(() => encrypt.getAuthTag(), errMessages.state);
+  assert.throws(() => encrypt.setAAD(Buffer.from('123', 'ascii')),
+                errMessages.state);
 }

test/parallel/test-crypto-cipheriv-decipheriv.js

@@ -66,12 +66,14 @@ testCipher2(Buffer.from('0123456789abcd0123456789'), Buffer.from('12345678'));
 // Zero-sized IV should be accepted in ECB mode.
 crypto.createCipheriv('aes-128-ecb', Buffer.alloc(16), Buffer.alloc(0));
 
+const errMessage = /Invalid IV length/;
+
 // But non-empty IVs should be rejected.
 for (let n = 1; n < 256; n += 1) {
   assert.throws(
       () => crypto.createCipheriv('aes-128-ecb', Buffer.alloc(16),
                                   Buffer.alloc(n)),
-      /Invalid IV length/);
+      errMessage);
 }
 
 // Correctly sized IV should be accepted in CBC mode.
@@ -83,14 +85,14 @@ for (let n = 0; n < 256; n += 1) {
   assert.throws(
       () => crypto.createCipheriv('aes-128-cbc', Buffer.alloc(16),
                                   Buffer.alloc(n)),
-      /Invalid IV length/);
+      errMessage);
 }
 
 // Zero-sized IV should be rejected in GCM mode.
 assert.throws(
     () => crypto.createCipheriv('aes-128-gcm', Buffer.alloc(16),
                                 Buffer.alloc(0)),
-    /Invalid IV length/);
+    errMessage);
 
 // But all other IV lengths should be accepted.
 for (let n = 1; n < 256; n += 1) {

test/parallel/test-crypto-dh.js

@@ -280,14 +280,15 @@ if (availableCurves.has('prime256v1') && availableCurves.has('secp256k1')) {
   // rejected.
   ecdh5.setPrivateKey(cafebabeKey, 'hex');
 
-  [ // Some invalid private keys for the secp256k1 curve.
-    '0000000000000000000000000000000000000000000000000000000000000000',
-    'FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141',
-    'FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF',
+  // Some invalid private keys for the secp256k1 curve.
+  const errMessage = /^Error: Private key is not valid for specified curve.$/;
+  ['0000000000000000000000000000000000000000000000000000000000000000',
+   'FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141',
+   'FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF',
   ].forEach((element) => {
     assert.throws(() => {
       ecdh5.setPrivateKey(element, 'hex');
-    }, /^Error: Private key is not valid for specified curve.$/);
+    }, errMessage);
     // Verify object state did not change.
     assert.strictEqual(ecdh5.getPrivateKey('hex'), cafebabeKey);
   });

test/parallel/test-crypto.js

@@ -78,7 +78,8 @@ validateList(cryptoCiphers);
 const tlsCiphers = tls.getCiphers();
 assert(tls.getCiphers().includes('aes256-sha'));
 // There should be no capital letters in any element.
-assert(tlsCiphers.every((value) => /^[^A-Z]+$/.test(value)));
+const noCapitals = /^[^A-Z]+$/;
+assert(tlsCiphers.every((value) => noCapitals.test(value)));
 validateList(tlsCiphers);
 
 // Assert that we have sha and sha1 but not SHA and SHA1.

test/parallel/test-error-reporting.js

@@ -21,6 +21,8 @@ function errExec(script, callback) {
   });
 }
 
+const syntaxErrorMessage = /SyntaxError/;
+
 
 // Simple throw error
 errExec('throws_error.js', common.mustCall(function(err, stdout, stderr) {
@@ -30,30 +32,30 @@ errExec('throws_error.js', common.mustCall(function(err, stdout, stderr) {
 
 // Trying to JSON.parse(undefined)
 errExec('throws_error2.js', common.mustCall(function(err, stdout, stderr) {
-  assert.ok(/SyntaxError/.test(stderr));
+  assert.ok(syntaxErrorMessage.test(stderr));
 }));
 
 
 // Trying to JSON.parse(undefined) in nextTick
 errExec('throws_error3.js', common.mustCall(function(err, stdout, stderr) {
-  assert.ok(/SyntaxError/.test(stderr));
+  assert.ok(syntaxErrorMessage.test(stderr));
 }));
 
 
 // throw ILLEGAL error
 errExec('throws_error4.js', common.mustCall(function(err, stdout, stderr) {
   assert.ok(/\/\*\*/.test(stderr));
-  assert.ok(/SyntaxError/.test(stderr));
+  assert.ok(syntaxErrorMessage.test(stderr));
 }));
 
 // Specific long exception line doesn't result in stack overflow
 errExec('throws_error5.js', common.mustCall(function(err, stdout, stderr) {
-  assert.ok(/SyntaxError/.test(stderr));
+  assert.ok(syntaxErrorMessage.test(stderr));
 }));
 
 // Long exception line with length > errorBuffer doesn't result in assertion
 errExec('throws_error6.js', common.mustCall(function(err, stdout, stderr) {
-  assert.ok(/SyntaxError/.test(stderr));
+  assert.ok(syntaxErrorMessage.test(stderr));
 }));
 
 // Object that throws in toString() doesn't print garbage

test/parallel/test-event-emitter-max-listeners.js

@@ -9,16 +9,10 @@ e.on('maxListeners', common.mustCall(function() {}));
 // Should not corrupt the 'maxListeners' queue.
 e.setMaxListeners(42);
 
-assert.throws(function() {
-  e.setMaxListeners(NaN);
-}, /^TypeError: "n" argument must be a positive number$/);
+const maxError = /^TypeError: "n" argument must be a positive number$/;
 
-assert.throws(function() {
-  e.setMaxListeners(-1);
-}, /^TypeError: "n" argument must be a positive number$/);
-
-assert.throws(function() {
-  e.setMaxListeners('and even this');
-}, /^TypeError: "n" argument must be a positive number$/);
+assert.throws(function() { e.setMaxListeners(NaN); }, maxError);
+assert.throws(function() { e.setMaxListeners(-1); }, maxError);
+assert.throws(function() { e.setMaxListeners('and even this'); }, maxError);
 
 e.emit('maxListeners');

test/parallel/test-fs-null-bytes.js

@@ -7,7 +7,7 @@ function check(async, sync) {
   const expected = /Path must be a string without null bytes/;
   const argsSync = Array.prototype.slice.call(arguments, 2);
   const argsAsync = argsSync.concat((er) => {
-    assert(er && er.message.match(expected));
+    assert(er && expected.test(er.message));
     assert.strictEqual(er.code, 'ENOENT');
   });
 

test/parallel/test-fs-read-stream-throw-type-error.js

@@ -16,18 +16,19 @@ assert.doesNotThrow(function() {
   fs.createReadStream(example, {encoding: 'utf8'});
 });
 
+const errMessage = /"options" argument must be a string or an object/;
 assert.throws(function() {
   fs.createReadStream(example, null);
-}, /"options" argument must be a string or an object/);
+}, errMessage);
 assert.throws(function() {
   fs.createReadStream(example, 123);
-}, /"options" argument must be a string or an object/);
+}, errMessage);
 assert.throws(function() {
   fs.createReadStream(example, 0);
-}, /"options" argument must be a string or an object/);
+}, errMessage);
 assert.throws(function() {
   fs.createReadStream(example, true);
-}, /"options" argument must be a string or an object/);
+}, errMessage);
 assert.throws(function() {
   fs.createReadStream(example, false);
-}, /"options" argument must be a string or an object/);
+}, errMessage);

test/parallel/test-global-console-exists.js

@@ -24,7 +24,7 @@ process.on('warning', (warning) => {
 
 process.stderr.write = (data) => {
   if (write_calls === 0)
-    assert.ok(data.match(leak_warning));
+    assert.ok(leak_warning.test(data));
   else
     common.fail('stderr.write should be called only once');
 

test/parallel/test-http-client-unescaped-path.js

@@ -3,8 +3,8 @@ const common = require('../common');
 const assert = require('assert');
 const http = require('http');
 
+const errMessage = /contains unescaped characters/;
 for (let i = 0; i <= 32; i += 1) {
   const path = `bad${String.fromCharCode(i)}path`;
-  assert.throws(() => http.get({ path }, common.mustNotCall()),
-                /contains unescaped characters/);
+  assert.throws(() => http.get({ path }, common.mustNotCall()), errMessage);
 }

test/parallel/test-http-server.js

@@ -95,10 +95,10 @@ process.on('exit', function() {
   assert.strictEqual(4, requests_sent);
 
   const hello = new RegExp('/hello');
-  assert.notStrictEqual(null, hello.exec(server_response));
+  assert.ok(hello.test(server_response));
 
   const quit = new RegExp('/quit');
-  assert.notStrictEqual(null, quit.exec(server_response));
+  assert.ok(quit.test(server_response));
 
   assert.strictEqual(true, client_got_eof);
 });