[Build] Modify run test script to filter by lang (uber#423)

### Summary:
Now we have CC and Java tests (cc_test and java_test targets). 
Script build/run_bazel_tests.sh allows to specify --lang flag. For example:
python ../build/run_bazel_tests.py --lang java
python ../build/run_bazel_tests.py --lang cc

By default it runs tests for all langs:
python ../build/run_bazel_tests.py

### Test Plan:
Run 
build/test.sh 
python ../build/run_bazel_tests.py --lang java
python ../build/run_bazel_tests.py --lang cc

build/run_cpp_tests.py → build/run_bazel_tests.py

@@ -50,16 +50,20 @@ def test(self):
 
 if __name__ == '__main__':
     # Parse args
-    parser = argparse.ArgumentParser(description='Run C++ Neuropod tests')
+    parser = argparse.ArgumentParser(description='Run Neuropod tests')
+
+    # --lang flag allows cc, java. Default is empty that means all.
+    parser.add_argument('--lang', action='store', default="")
     parser.add_argument('--run-gpu-tests', action='store_true')
     args = parser.parse_args()
 
-    # Get all the bazel test targets
-    cpp_tests = []
-    cpp_tests_xml = subprocess.check_output(['bazel', 'query', 'kind(".*_test rule", //...)', '--output=xml'])
+    # Get all the bazel test targets that match lang argument
+    lang_tests = []
+    kind_pattern = 'kind(".*{lang}_test rule", //...)'.format(lang=args.lang)
+    lang_tests_xml = subprocess.check_output(['bazel', 'query', kind_pattern, '--output=xml'])
 
     # Parse the xml
-    root = ET.fromstring(cpp_tests_xml)
+    root = ET.fromstring(lang_tests_xml)
     for child in root:
 
         # Get tags (if any)
@@ -70,11 +74,11 @@ def test(self):
                 for tag in prop:
                     tags.append(tag.attrib["value"])
 
-        cpp_tests.append((child.attrib["name"], tags))
+        lang_tests.append((child.attrib["name"], tags))
 
 
     # Generate unittests for each bazel test target
-    for test_target, tags in cpp_tests:
+    for test_target, tags in lang_tests:
         # Skip GPU tests by default
         if "gpu" in tags and not args.run_gpu_tests:
             continue

build/test.sh

@@ -34,8 +34,8 @@ NEUROPOD_LOG_LEVEL=TRACE python -m unittest discover --verbose neuropod/tests
 NEUROPOD_LOG_LEVEL=TRACE NEUROPOD_RUN_NATIVE_TESTS=true python -m unittest discover --verbose neuropod/tests
 popd
 
-# Run native tests
-python ../build/run_cpp_tests.py
+# Run native and java tests
+python ../build/run_bazel_tests.py
 popd
 
 # Maybe upload a release

build/test_gpu.sh

@@ -52,7 +52,7 @@ NEUROPOD_LOG_LEVEL=TRACE NEUROPOD_RUN_NATIVE_TESTS=true python -m unittest disco
 popd
 
 # Run native tests
-python ../build/run_cpp_tests.py --run-gpu-tests
+python ../build/run_bazel_tests.py --run-gpu-tests
 popd
 
 # Maybe upload a release