[lit] Add back LitTestCase

This essentially reverts a commit [1] that removed the adaptor for
Python unittests.  The code has been slightly refactored to make it more
additive: all code is contained in LitTestCase.py.

Usage sites will require a small adaption:
```
[old]
  import lit.discovery
  ...
  test_suite = lit.discovery.load_test_suite(...)

[new]
  import lit.LitTestCase
  ...
  test_suite = lit.LitTestCase.load_test_suite(...)
```

This was put back on request by Daniel Dunbar, since I wrongly assumed
that the functionality is unused.  At least llbuild still uses this [2].

[1] 70ca752ccf6a8f362aea25ccd3ee2bbceca93b20
[2] https://github.com/apple/swift-llbuild/blob/master/utils/Xcode/LitXCTestAdaptor/LitTests.py#L16

Reviewed By: ddunbar

Differential Revision: https://reviews.llvm.org/D69002

llvm-svn: 374947

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/utils/lit/tests/unittest-adaptor.py b/llvm/utils/lit/tests/unittest-adaptor.py
new file mode 100644
index 00000000000..ee2eee4572e
--- /dev/null
+++ b/llvm/utils/lit/tests/unittest-adaptor.py
@@ -0,0 +1,17 @@
+# Check the lit adaption to run under unittest.
+#
+# RUN: %{python} %s %{inputs}/unittest-adaptor 2> %t.err
+# RUN: FileCheck < %t.err %s
+#
+# CHECK-DAG: unittest-adaptor :: test-two.txt ... FAIL
+# CHECK-DAG: unittest-adaptor :: test-one.txt ... ok
+
+import sys
+import unittest
+
+import lit.LitTestCase
+
+input_path = sys.argv[1]
+unittest_suite = lit.LitTestCase.load_test_suite([input_path])
+runner = unittest.TextTestRunner(verbosity=2)
+runner.run(unittest_suite)