diff --git a/test/crossrunner/collect.py b/test/crossrunner/collect.py
index f92b9e2..e91ac0b 100644
--- a/test/crossrunner/collect.py
+++ b/test/crossrunner/collect.py
@@ -40,13 +40,13 @@
 # (e.g. "binary" is equivalent to "binary:binary" in tests.json)
 #
 VALID_JSON_KEYS = [
-  'name',  # name of the library, typically a language name
-  'workdir',  # work directory where command is executed
-  'command',  # test command
-  'extra_args',  # args appended to command after other args are appended
-  'remote_args',  # args added to the other side of the program
-  'join_args',  # whether args should be passed as single concatenated string
-  'env',  # additional environmental variable
+    'name',  # name of the library, typically a language name
+    'workdir',  # work directory where command is executed
+    'command',  # test command
+    'extra_args',  # args appended to command after other args are appended
+    'remote_args',  # args added to the other side of the program
+    'join_args',  # whether args should be passed as single concatenated string
+    'env',  # additional environmental variable
 ]
 
 DEFAULT_DELAY = 1
@@ -54,102 +54,102 @@
 
 
 def _collect_testlibs(config, server_match, client_match=[None]):
-  """Collects server/client configurations from library configurations"""
-  def expand_libs(config):
-    for lib in config:
-      sv = lib.pop('server', None)
-      cl = lib.pop('client', None)
-      yield lib, sv, cl
+    """Collects server/client configurations from library configurations"""
+    def expand_libs(config):
+        for lib in config:
+            sv = lib.pop('server', None)
+            cl = lib.pop('client', None)
+            yield lib, sv, cl
 
-  def yield_testlibs(base_configs, configs, match):
-    for base, conf in zip(base_configs, configs):
-      if conf:
-        if not match or base['name'] in match:
-          platforms = conf.get('platforms') or base.get('platforms')
-          if not platforms or platform.system() in platforms:
-            yield merge_dict(base, conf)
+    def yield_testlibs(base_configs, configs, match):
+        for base, conf in zip(base_configs, configs):
+            if conf:
+                if not match or base['name'] in match:
+                    platforms = conf.get('platforms') or base.get('platforms')
+                    if not platforms or platform.system() in platforms:
+                        yield merge_dict(base, conf)
 
-  libs, svs, cls = zip(*expand_libs(config))
-  servers = list(yield_testlibs(libs, svs, server_match))
-  clients = list(yield_testlibs(libs, cls, client_match))
-  return servers, clients
+    libs, svs, cls = zip(*expand_libs(config))
+    servers = list(yield_testlibs(libs, svs, server_match))
+    clients = list(yield_testlibs(libs, cls, client_match))
+    return servers, clients
 
 
 def collect_features(config, match):
-  res = list(map(re.compile, match))
-  return list(filter(lambda c: any(map(lambda r: r.search(c['name']), res)), config))
+    res = list(map(re.compile, match))
+    return list(filter(lambda c: any(map(lambda r: r.search(c['name']), res)), config))
 
 
 def _do_collect_tests(servers, clients):
-  def intersection(key, o1, o2):
-    """intersection of two collections.
-    collections are replaced with sets the first time"""
-    def cached_set(o, key):
-      v = o[key]
-      if not isinstance(v, set):
-        v = set(v)
-        o[key] = v
-      return v
-    return cached_set(o1, key) & cached_set(o2, key)
+    def intersection(key, o1, o2):
+        """intersection of two collections.
+        collections are replaced with sets the first time"""
+        def cached_set(o, key):
+            v = o[key]
+            if not isinstance(v, set):
+                v = set(v)
+                o[key] = v
+            return v
+        return cached_set(o1, key) & cached_set(o2, key)
 
-  def intersect_with_spec(key, o1, o2):
-    # store as set of (spec, impl) tuple
-    def cached_set(o):
-      def to_spec_impl_tuples(values):
-        for v in values:
-          spec, _, impl = v.partition(':')
-          yield spec, impl or spec
-      v = o[key]
-      if not isinstance(v, set):
-        v = set(to_spec_impl_tuples(set(v)))
-        o[key] = v
-      return v
-    for spec1, impl1 in cached_set(o1):
-      for spec2, impl2 in cached_set(o2):
-        if spec1 == spec2:
-          name = impl1 if impl1 == impl2 else '%s-%s' % (impl1, impl2)
-          yield name, impl1, impl2
+    def intersect_with_spec(key, o1, o2):
+        # store as set of (spec, impl) tuple
+        def cached_set(o):
+            def to_spec_impl_tuples(values):
+                for v in values:
+                    spec, _, impl = v.partition(':')
+                    yield spec, impl or spec
+            v = o[key]
+            if not isinstance(v, set):
+                v = set(to_spec_impl_tuples(set(v)))
+                o[key] = v
+            return v
+        for spec1, impl1 in cached_set(o1):
+            for spec2, impl2 in cached_set(o2):
+                if spec1 == spec2:
+                    name = impl1 if impl1 == impl2 else '%s-%s' % (impl1, impl2)
+                    yield name, impl1, impl2
 
-  def maybe_max(key, o1, o2, default):
-    """maximum of two if present, otherwise defult value"""
-    v1 = o1.get(key)
-    v2 = o2.get(key)
-    return max(v1, v2) if v1 and v2 else v1 or v2 or default
+    def maybe_max(key, o1, o2, default):
+        """maximum of two if present, otherwise defult value"""
+        v1 = o1.get(key)
+        v2 = o2.get(key)
+        return max(v1, v2) if v1 and v2 else v1 or v2 or default
 
-  def filter_with_validkeys(o):
-    ret = {}
-    for key in VALID_JSON_KEYS:
-      if key in o:
-        ret[key] = o[key]
-    return ret
+    def filter_with_validkeys(o):
+        ret = {}
+        for key in VALID_JSON_KEYS:
+            if key in o:
+                ret[key] = o[key]
+        return ret
 
-  def merge_metadata(o, **ret):
-    for key in VALID_JSON_KEYS:
-      if key in o:
-        ret[key] = o[key]
-    return ret
+    def merge_metadata(o, **ret):
+        for key in VALID_JSON_KEYS:
+            if key in o:
+                ret[key] = o[key]
+        return ret
 
-  for sv, cl in product(servers, clients):
-    for proto, proto1, proto2 in intersect_with_spec('protocols', sv, cl):
-      for trans, trans1, trans2 in intersect_with_spec('transports', sv, cl):
-        for sock in intersection('sockets', sv, cl):
-          yield {
-            'server': merge_metadata(sv, **{'protocol': proto1, 'transport': trans1}),
-            'client': merge_metadata(cl, **{'protocol': proto2, 'transport': trans2}),
-            'delay': maybe_max('delay', sv, cl, DEFAULT_DELAY),
-            'timeout': maybe_max('timeout', sv, cl, DEFAULT_TIMEOUT),
-            'protocol': proto,
-            'transport': trans,
-            'socket': sock
-          }
+    for sv, cl in product(servers, clients):
+        for proto, proto1, proto2 in intersect_with_spec('protocols', sv, cl):
+            for trans, trans1, trans2 in intersect_with_spec('transports', sv, cl):
+                for sock in intersection('sockets', sv, cl):
+                    yield {
+                        'server': merge_metadata(sv, **{'protocol': proto1, 'transport': trans1}),
+                        'client': merge_metadata(cl, **{'protocol': proto2, 'transport': trans2}),
+                        'delay': maybe_max('delay', sv, cl, DEFAULT_DELAY),
+                        'timeout': maybe_max('timeout', sv, cl, DEFAULT_TIMEOUT),
+                        'protocol': proto,
+                        'transport': trans,
+                        'socket': sock
+                    }
 
 
 def collect_cross_tests(tests_dict, server_match, client_match):
-  sv, cl = _collect_testlibs(tests_dict, server_match, client_match)
-  return list(_do_collect_tests(sv, cl))
+    sv, cl = _collect_testlibs(tests_dict, server_match, client_match)
+    return list(_do_collect_tests(sv, cl))
 
 
 def collect_feature_tests(tests_dict, features_dict, server_match, feature_match):
-  sv, _ = _collect_testlibs(tests_dict, server_match)
-  ft = collect_features(features_dict, feature_match)
-  return list(_do_collect_tests(sv, ft))
+    sv, _ = _collect_testlibs(tests_dict, server_match)
+    ft = collect_features(features_dict, feature_match)
+    return list(_do_collect_tests(sv, ft))