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.

PR-URL: https://github.com/nodejs/node/pull/13770
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

3 files changed, 20 insertions, 14 deletions

diff --git a/test/sequential/test-module-loading.js b/test/sequential/test-module-loading.js
index c55c03279e..8a7bfe15c4 100644
--- a/test/sequential/test-module-loading.js
+++ b/test/sequential/test-module-loading.js
@@ -25,6 +25,8 @@ const assert = require('assert');
 const path = require('path');
 const fs = require('fs');
 
+const backslash = /\\/g;
+
 console.error('load test-module-loading.js');
 
 // assert that this is the main module.
@@ -195,7 +197,7 @@ try {
     require(`${loadOrder}file3`);
   } catch (e) {
     // Not a real .node module, but we know we require'd the right thing.
-    assert.ok(e.message.replace(/\\/g, '/').match(/file3\.node/));
+    assert.ok(/file3\.node/.test(e.message.replace(backslash, '/')));
   }
   assert.strictEqual(require(`${loadOrder}file4`).file4, 'file4.reg', msg);
   assert.strictEqual(require(`${loadOrder}file5`).file5, 'file5.reg2', msg);
@@ -203,7 +205,7 @@ try {
   try {
     require(`${loadOrder}file7`);
   } catch (e) {
-    assert.ok(e.message.replace(/\\/g, '/').match(/file7\/index\.node/));
+    assert.ok(/file7\/index\.node/.test(e.message.replace(backslash, '/')));
   }
   assert.strictEqual(require(`${loadOrder}file8`).file8, 'file8/index.reg',
                      msg);
@@ -237,7 +239,7 @@ try {
 
   const children = module.children.reduce(function red(set, child) {
     let id = path.relative(path.dirname(__dirname), child.id);
-    id = id.replace(/\\/g, '/');
+    id = id.replace(backslash, '/');
     set[id] = child.children.reduce(red, {});
     return set;
   }, {});
diff --git a/test/sequential/test-process-warnings.js b/test/sequential/test-process-warnings.js
index 0ab8652f56..944029d8b3 100644
--- a/test/sequential/test-process-warnings.js
+++ b/test/sequential/test-process-warnings.js
@@ -10,24 +10,26 @@ const normal = [warnmod];
 const noWarn = ['--no-warnings', warnmod];
 const traceWarn = ['--trace-warnings', warnmod];
 
+const warningMessage = /^\(.+\)\sWarning: a bad practice warning/;
+
 execFile(node, normal, function(er, stdout, stderr) {
   // Show Process Warnings
   assert.strictEqual(er, null);
   assert.strictEqual(stdout, '');
-  assert(/^\(.+\)\sWarning: a bad practice warning/.test(stderr));
+  assert(warningMessage.test(stderr));
 });
 
 execFile(node, noWarn, function(er, stdout, stderr) {
   // Hide Process Warnings
   assert.strictEqual(er, null);
   assert.strictEqual(stdout, '');
-  assert(!/^\(.+\)\sWarning: a bad practice warning/.test(stderr));
+  assert(!warningMessage.test(stderr));
 });
 
 execFile(node, traceWarn, function(er, stdout, stderr) {
   // Show Warning Trace
   assert.strictEqual(er, null);
   assert.strictEqual(stdout, '');
-  assert(/^\(.+\)\sWarning: a bad practice warning/.test(stderr));
+  assert(warningMessage.test(stderr));
   assert(/at Object\.<anonymous>\s\(.+warnings\.js:3:9\)/.test(stderr));
 });
diff --git a/test/sequential/test-regress-GH-784.js b/test/sequential/test-regress-GH-784.js
index 7abc622dbe..127d921626 100644
--- a/test/sequential/test-regress-GH-784.js
+++ b/test/sequential/test-regress-GH-784.js
@@ -70,28 +70,30 @@ const responses = [];
 function afterPing(result) {
   responses.push(result);
   console.error(`afterPing. responses.length = ${responses.length}`);
+  const ECONNREFUSED_RE = /ECONNREFUSED/;
+  const successRE = /success/;
   switch (responses.length) {
     case 2:
-      assert.ok(/ECONNREFUSED/.test(responses[0]));
-      assert.ok(/ECONNREFUSED/.test(responses[1]));
+      assert.ok(ECONNREFUSED_RE.test(responses[0]));
+      assert.ok(ECONNREFUSED_RE.test(responses[1]));
       serverOn();
       break;
 
     case 4:
-      assert.ok(/success/.test(responses[2]));
-      assert.ok(/success/.test(responses[3]));
+      assert.ok(successRE.test(responses[2]));
+      assert.ok(successRE.test(responses[3]));
       serverOff();
       break;
 
     case 6:
-      assert.ok(/ECONNREFUSED/.test(responses[4]));
-      assert.ok(/ECONNREFUSED/.test(responses[5]));
+      assert.ok(ECONNREFUSED_RE.test(responses[4]));
+      assert.ok(ECONNREFUSED_RE.test(responses[5]));
       serverOn();
       break;
 
     case 8:
-      assert.ok(/success/.test(responses[6]));
-      assert.ok(/success/.test(responses[7]));
+      assert.ok(successRE.test(responses[6]));
+      assert.ok(successRE.test(responses[7]));
       server.close();
       // we should go to process.on('exit') from here.
       break;