[python] [tests] Remove cdb lookup failure test

Remove the test checking for compilation db lookup failure.
Since r342228, JSONCompilationDatabasePlugin infers compile commands for
missing files, therefore making the lookup always succeed.

Differential Revision: https://reviews.llvm.org/D53202

llvm-svn: 344364

Author: mgorny

clang/bindings/python/tests/cindex/test_cdb.py

@@ -31,11 +31,6 @@ def test_create(self):
         """Check we can load a compilation database"""
         cdb = CompilationDatabase.fromDirectory(kInputsDir)
 
-    def test_lookup_fail(self):
-        """Check file lookup failure"""
-        cdb = CompilationDatabase.fromDirectory(kInputsDir)
-        self.assertIsNone(cdb.getCompileCommands('file_do_not_exist.cpp'))
-
     def test_lookup_succeed(self):
         """Check we get some results if the file exists in the db"""
         cdb = CompilationDatabase.fromDirectory(kInputsDir)