Bug 1642709 - Make a relative path from topsrcdir work in jstestbrowser. r=jmaher

jsreftest tests are staged into objdir, and specifying a path inside it isn't
user friendly.

Made it automatically try resolving the relative path from staged area, if
the relative path doesn't find any test.

Differential Revision: https://phabricator.services.mozilla.com/D106010

layout/tools/reftest/reftestcommandline.py

@@ -308,7 +308,10 @@ class ReftestArgumentsParser(argparse.ArgumentParser):
             "tests",
             metavar="TEST_PATH",
             nargs="*",
-            help="Path to test file, manifest file, or directory containing tests",
+            help="Path to test file, manifest file, or directory containing "
+            "tests. For jstestbrowser, the relative path can be either from "
+            "topsrcdir or the staged area "
+            "($OBJDIR/dist/test-stage/jsreftest/tests)",
         )
 
         self.add_argument(

layout/tools/reftest/runreftest.py

@@ -216,7 +216,9 @@ class ReftestResolver(object):
         """
         rv = []
         default_manifest = self.defaultManifest(suite)
+        relative_path = None
         if not os.path.isabs(test_file):
+            relative_path = test_file
             test_file = self.absManifestPath(test_file)
 
         if os.path.isdir(test_file):
@@ -227,6 +229,18 @@ class ReftestResolver(object):
                     # of include directives we get the same manifest multiple times.
                     # However reftest.js will only read each manifest once
 
+            if (
+                len(rv) == 0
+                and relative_path
+                and suite == "jstestbrowser"
+                and build_obj
+            ):
+                # The relative path can be from staging area.
+                staged_js_dir = os.path.join(
+                    build_obj.topobjdir, "dist", "test-stage", "jsreftest"
+                )
+                staged_file = os.path.join(staged_js_dir, "tests", relative_path)
+                return self.findManifest(suite, staged_file, subdirs)
         elif test_file.endswith(".list"):
             if os.path.exists(test_file):
                 rv = [(test_file, None)]