[unittests] Fix ExpandTilde test to match handling home dirs with trailing slash

[atanasyan]

Summary

The expandTildeExpr routine just replaces a tilde by a home dir path. If the home dir has a trailing slash, the result of substitution will contain double slash. For example, HOME=/foo/ ~/bar gives /foo//bar. That corresponds to (at least) Bash behaviour because the following command $HOME=/foo/ echo ~/bar prints /foo//bar.

The ExpandTilde test constructs a path expected as the fs::expand_tilde call result by calling path::append and the expected path has a single slash. This patch fixes that and allows to pass the unittest on hosts where the HOME is /.

[JDevlieghere]

LGTM. Thanks!

unittests/Support/Path.cpp

TEST_F(FileSystemTest, ExpandTilde) {
   // This can fail if $HOME is not set and getpwuid fails.
   bool Result = llvm::sys::path::home_directory(HomeDir);
   if (Result) {
     fs::expand_tilde(HomeDir, Expected);
 
     fs::expand_tilde("~", Actual);
     EXPECT_EQ(Expected, Actual);
 
-    path::append(Expected, "foo");
-
 #ifdef _WIN32
+    Expected += "\\foo";
     fs::expand_tilde("~\\foo", Actual);
 #else
+    Expected += "/foo";
     fs::expand_tilde("~/foo", Actual);
 #endif
 
     EXPECT_EQ(Expected, Actual);
   }
 }
 
 #ifdef LLVM_ON_UNIX