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>

1 files changed, 4 insertions, 2 deletions

diff --git a/test/parallel/test-zlib-truncated.js b/test/parallel/test-zlib-truncated.js
index c7b84c0d70..678bfedd41 100644
--- a/test/parallel/test-zlib-truncated.js
+++ b/test/parallel/test-zlib-truncated.js
@@ -15,6 +15,8 @@ const inputString = 'ΩΩLorem ipsum dolor sit amet, consectetur adipiscing eli'
                     'm arcu mi, sodales non suscipit id, ultrices ut massa. S' +
                     'ed ac sem sit amet arcu malesuada fermentum. Nunc sed. ';
 
+const errMessage = /unexpected end of file/;
+
 [
   { comp: 'gzip', decomp: 'gunzip', decompSync: 'gunzipSync' },
   { comp: 'gzip', decomp: 'unzip', decompSync: 'unzipSync' },
@@ -41,11 +43,11 @@ const inputString = 'ΩΩLorem ipsum dolor sit amet, consectetur adipiscing eli'
     // sync truncated input test
     assert.throws(function() {
       zlib[methods.decompSync](truncated);
-    }, /unexpected end of file/);
+    }, errMessage);
 
     // async truncated input test
     zlib[methods.decomp](truncated, function(err, result) {
-      assert(/unexpected end of file/.test(err.message));
+      assert(errMessage.test(err.message));
     });
 
     const syncFlushOpt = { finishFlush: zlib.constants.Z_SYNC_FLUSH };