[lit] Move unittest adaptor code into discovery module.

- Also, add a test for it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174019 91177308-0d34-0410-b5e6-96231b3b80d8

utils/lit/tests/Inputs/unittest-adaptor/lit.cfg

@@ -0,0 +1,5 @@
+config.name = 'unittest-adaptor'
+config.suffixes = ['.txt']
+config.test_format = lit.formats.ShTest()
+config.test_source_root = None
+config.test_exec_root = None

utils/lit/tests/Inputs/unittest-adaptor/test-one.txt

@@ -0,0 +1 @@
+# RUN: true

utils/lit/tests/Inputs/unittest-adaptor/test-two.txt

@@ -0,0 +1 @@
+# RUN: false

utils/lit/tests/unittest-adaptor.py

@@ -0,0 +1,18 @@
+# Check the lit adaption to run under unittest.
+#
+# RUN: python %s %{inputs}/unittest-adaptor 2> %t.err
+# RUN: FileCheck < %t.err %s
+#
+# CHECK: unittest-adaptor :: test-one.txt ... ok
+# CHECK: unittest-adaptor :: test-two.txt ... FAIL
+
+import unittest
+import sys
+
+import lit
+import lit.discovery
+
+input_path = sys.argv[1]
+unittest_suite = lit.discovery.load_test_suite([input_path])
+runner = unittest.TextTestRunner(verbosity=2)
+runner.run(unittest_suite)