make test: separate test discovery code

Separating test discovery code to it's own script file has the
advantage of easily doing e.g. listing of all existing tests.

Change-Id: I80dc280263cc7e33e7e13cb0d48b39bf08ece24d
Signed-off-by: Klement Sekera <ksekera@cisco.com>

test/discover_tests.py

@@ -0,0 +1,57 @@
+#!/usr/bin/env python
+
+import sys
+import os
+import unittest
+import importlib
+import argparse
+
+
+def discover_tests(directory, callback):
+    do_insert = True
+    for _f in os.listdir(directory):
+        f = "%s/%s" % (directory, _f)
+        if os.path.isdir(f):
+            discover_tests(f, callback)
+            continue
+        if not os.path.isfile(f):
+            continue
+        if do_insert:
+            sys.path.insert(0, directory)
+            do_insert = False
+        if not _f.startswith("test_") or not _f.endswith(".py"):
+            continue
+        name = "".join(f.split("/")[-1].split(".")[:-1])
+        if name in sys.modules:
+            raise Exception("Duplicate test module `%s' found!" % name)
+        module = importlib.import_module(name)
+        for name, cls in module.__dict__.items():
+            if not isinstance(cls, type):
+                continue
+            if not issubclass(cls, unittest.TestCase):
+                continue
+            if name == "VppTestCase":
+                continue
+            for method in dir(cls):
+                if not callable(getattr(cls, method)):
+                    continue
+                if method.startswith("test_"):
+                    callback(_f, cls, method)
+
+
+def print_callback(file_name, cls, method):
+    print("%s.%s.%s" % (file_name, cls.__name__, method))
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description="Discover VPP unit tests")
+    parser.add_argument("-d", "--dir", action='append', type=str,
+                        help="directory containing test files "
+                             "(may be specified multiple times)")
+    args = parser.parse_args()
+    if args.dir is None:
+        args.dir = "."
+
+    suite = unittest.TestSuite()
+    for d in args.dir:
+        discover_tests(d, print_callback)