Allow singling out a particular test

[nzakas]

One of the issues I've been having as I'm trying to fix things is that the custom test runner is a bit difficult to work with when trying to focus on a specific issue. After several cycles of commenting out every test except the one I'm working on, I hacked in testOnly, testFailOnly and testAssertOnly locally and found that it really helped. Basically, the first one of these wins and all other tests are ignored. Here's the diff:

diff --git a/test/driver.js b/test/driver.js
index ed48ace..a582b93 100644
--- a/test/driver.js
+++ b/test/driver.js
@@ -1,16 +1,32 @@
 (function(exports) {
-  var tests = [];
+  var tests = [], only = false;

   exports.test = function(code, ast, options) {
+    if (only) return;
     tests.push({code: code, ast: ast, options: options});
   };
   exports.testFail = function(code, message, options) {
+    if (only) return;
     tests.push({code: code, error: message, options: options});
   };
   exports.testAssert = function(code, assert, options) {
+    if (only) return;
     tests.push({code: code, assert: assert, options: options});
   };

+  exports.testOnly = function(code, ast, options) {
+    tests = [{code: code, ast: ast, options: options}];
+    only = true;
+  };
+  exports.testFailOnly = function(code, message, options) {
+    tests = [{code: code, error: message, options: options}];
+    only = true;
+  };
+  exports.testAssertOnly = function(code, assert, options) {
+    tests = [{code: code, assert: assert, options: options}];
+    only = true;
+  };
+
   exports.runTests = function(config, callback) {
     var parse = config.parse;

Would you be open to including this in Acorn?

[marijnh]

If someone has good experiences with a test runner module, I'm also definitely open to moving to a proper test framework. (I haven't run into any I liked, but I haven't used a lot.)

[RReverser]

@marijnh That would be great. Personally, I like Mocha, but we could also stick with something as minimal as Tape. However, we still need to use own wrappers for AST comparison in any case.

[platinumazure]

For what it's worth, typescript-eslint-parser has recently moved to Jest for testing. Jest has a snapshot feature which may or may not be useful to this project for AST deep-compares. Would that be worth looking into at all?

[RReverser]

@platinumazure I played with snapshots (without Jest) for Acorn tests, but not quite sure yet if it helps - diffs are still way too noisy and now you need to check two places instead of one when updating them, so decided not to proceed for now.

[marijnh]

I'm not a big fan of snapshot testing -- using unvetted possibly wrong output as reference data, and committing huge blobs of that to the repository, feels dirty, and as @RReverser mentions, working with them often gets noisy and awkward. But I'm willing to be convinced if someone has good arguments in favor of it.

[KentAKA1970]

Thanks
Thanks