isa<> tests

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108851 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/Support/Casting.cpp b/unittests/Support/Casting.cpp
index d7e89f8..3a3af7e 100644
--- a/unittests/Support/Casting.cpp
+++ b/unittests/Support/Casting.cpp
@@ -22,8 +22,14 @@
 extern bar &B1;
 extern const bar *B2;
 
-TEST(CastingTest, Basics) {
+TEST(CastingTest, isa) {
+  // test various configurations of const
+  const bar &B3 = B1;
+  const bar *const B4 = B2;
   EXPECT_TRUE(isa<foo>(B1));
+  EXPECT_TRUE(isa<foo>(B2));
+  EXPECT_TRUE(isa<foo>(B3));
+  EXPECT_TRUE(isa<foo>(B4));
 }
 
 bar B;