Allow supplying `RunSyntaxTestsCommand` a custom formatter

Problem description

Reading syntax tests' output feels downright painful when scopes start to span multiple lines:

WindowsTerminal_6LXevu3ryK

Does the problem lie with the tests themselves? I don't think so - at times, complexity is unavoidable, and nested contexts tend to bring a lot of clutter with them; rather, I think it's a matter of presentation - not knowing where to look when reading output containing lengthy scopes is...

On the other hand, it's not possible to appeal to everyone - people have their own preferences regarding how an easier to parse output should look like, as previous discussions showed.

Preferred solution

Make RunSyntaxTestsCommand accept a custom formatter as a parameter:

[
  { "keys": (...), "command": "run_syntax_tests", "args": 
    {
      "find_all": (...),
      "syntax": (...),
      "formatter": "{file}:{line}:{column}\n  expect: {expected}\n   found: {actual}\n"
    }
  },
]

Custom syntax + custom formatter = free reign.

Alternatives

Overriding run_syntax_tests.py locally, modifying RunSyntaxTestsCommand at the very least.

Additional Information

Feel free to use the following patch as you deem fit - I don't know how sublime_api.run_syntax_test(...) works exactly, but this assumes it would return list[dict[...]] with failure details instead of list[str]:

diff --git a/Default/run_syntax_tests.py b/Default/run_syntax_tests.py
index 8ec24b73b4a2..228347c2b61f 100644
--- a/Default/run_syntax_tests.py
+++ b/Default/run_syntax_tests.py
@@ -13,12 +13,16 @@ class RunSyntaxTestsCommand(sublime_plugin.WindowCommand):
     def run(self,
             find_all=False,
             syntax='Plain text.tmLanguage',
+            formatter=None,
             **kwargs):

         if not hasattr(self, 'output_view'):
             # Try not to call get_output_panel until the regexes are assigned
             self.output_view = self.window.create_output_panel('exec')

+        if formatter is None:
+            formatter = '{file}:{line}:{column}: [{expected}] does not match scope [{actual}]\n'
+
         settings = self.output_view.settings()
         settings.set('result_file_regex', PACKAGES_FILE_REGEX)
@@ -69,13 +73,12 @@ class RunSyntaxTestsCommand(sublime_plugin.WindowCommand):
         total_assertions = 0
         failed_assertions = 0

-        for t in tests:
-            assertions, test_output_lines = sublime_api.run_syntax_test(t)
+        for test in tests:
+            assertions, failures = sublime_api.run_syntax_test(test)
             total_assertions += assertions
-            if len(test_output_lines) > 0:
-                failed_assertions += len(test_output_lines)
-                for line in test_output_lines:
-                    append(self.output_view, line + '\n')
+            if failures:
+                failed_assertions += len(failures)
+                append(self.output_view, ''.join(formatter.format(failure) for failure in failures))

         if failed_assertions > 0:
             message = 'FAILED: {} of {} assertions in {} files failed\n'

Related: #3022 (though that issue centers on syntax, not semantics)

sublimehq / sublime_text