--- a/testing/cppunittest.ini
+++ b/testing/cppunittest.ini
@@ -1,14 +1,14 @@
 [ShowSSEConfig]
 [TestPrintf]
 [TestAlgorithm]
 [TestArray]
 [TestArrayUtils]
-[TestAtomicBitfields]
+[TestAtomicBitflags]
 [TestAtomics]
 [TestBinarySearch]
 [TestBitSet]
 [TestBloomFilter]
 [TestBufferList]
 [TestCasting]
 [TestCeilingFloor]
 [TestCheckedInt]
@@ -72,21 +72,23 @@ skip-if = os == 'android' # Bug 1147630
 [TestRollingMean]
 [TestScopeExit]
 [TestSegmentedVector]
 [TestSHA1]
 [TestSmallPointerArray]
 [TestSaturate]
 [TestSplayTree]
 [TestSPSCQueue]
+[TestTainting]
 [TestTemplateLib]
 [TestTextUtils]
 [TestThreadSafeWeakPtr]
 [TestTuple]
 [TestTypeTraits]
 [TestTypedEnum]
 [TestUniquePtr]
 [TestUtf8]
 [TestVariant]
 [TestVector]
 [TestWeakPtr]
 [TestWrappingOperations]
 [TestXorShift128PlusRNG]
+[jsapi-tests]

--- a/testing/runcppunittests.py
+++ b/testing/runcppunittests.py
@@ -267,18 +267,18 @@ def extract_unittests_from_args(args, en
                 except IOError:
                     files = [os.path.abspath(os.path.join(p, x)) for x in os.listdir(p)]
                     tests.extend(
                         (f, 1) for f in files if os.access(f, os.R_OK | os.X_OK)
                     )
             else:
                 tests.append((os.path.abspath(p), 1))
 
-    # We don't use the manifest parser's existence-check only because it will
-    # fail on Windows due to the `.exe` suffix.
+    # we skip the existence check here because not all tests are built
+    # for all platforms (and it will fail on Windows anyway)
     active_tests = mp.active_tests(exists=False, disabled=False, **environ)
     suffix = ".exe" if mozinfo.isWin else ""
     if binary_path:
         tests.extend(
             [
                 (
                     os.path.join(binary_path, test["relpath"] + suffix),
                     int(test.get("requesttimeoutfactor", 1)),
@@ -289,28 +289,26 @@ def extract_unittests_from_args(args, en
     else:
         tests.extend(
             [
                 (test["path"] + suffix, int(test.get("requesttimeoutfactor", 1)))
                 for test in active_tests
             ]
         )
 
-    # Manually confirm that all tests named in the manifest exist.
-    errors = False
+    # skip and warn for any tests in the manifest that are not found
+    final_tests = []
     log = mozlog.get_default_logger()
     for test in tests:
-        if not os.path.isfile(test[0]):
-            errors = True
-            log.error("test file not found: %s" % test[0])
+        if os.path.isfile(test[0]):
+            final_tests.append(test)
+        else:
+            log.warning("test file not found: %s - skipped" % test[0])
 
-    if errors:
-        raise RuntimeError("One or more cppunittests not found; aborting.")
-
-    return tests
+    return final_tests
 
 
 def update_mozinfo():
     """walk up directories to find mozinfo.json update the info"""
     path = SCRIPT_DIR
     dirs = set()
     while path != os.path.expanduser("~"):
         if path in dirs: