[libTooling][NFC] Switch StencilTest.cpp to use EXPECT_THAT_EXPECTED

[ymandel]

Summary

Currently, some tests use homegrown matchers to handle llvm::Expected
values. This revision standardizes on EXPECT_THAT_EXPECTED and HasValue.

[ilya-biryukov]

LGTM

clang/unittests/Tooling/StencilTest.cpp

 using ::testing::HasSubstr;
 using MatchResult = MatchFinder::MatchResult;
 using stencil::access;
 using stencil::cat;
 using stencil::dPrint;
 using stencil::ifBound;
 using stencil::text;
 
-// In tests, we can't directly match on llvm::Expected since its accessors
-// mutate the object. So, we collapse it to an Optional.
-static llvm::Optional<std::string> toOptional(llvm::Expected<std::string> V) {
-  if (V)
-    return *V;
-  ADD_FAILURE() << "Losing error in conversion to IsSomething: "
-                << llvm::toString(V.takeError());
-  return llvm::None;
-}
-
-// A very simple matcher for llvm::Optional values.
-MATCHER_P(IsSomething, ValueMatcher, "") {
-  if (!arg)
-    return false;
-  return ::testing::ExplainMatchResult(ValueMatcher, *arg, result_listener);
-}
-
 // Create a valid translation-unit from a statement.
 static std::string wrapSnippet(StringRef StatementCode) {
   return ("struct S { int field; }; auto stencil_test_snippet = []{" +
           StatementCode + "};")
       .str();
 }
 
 static DeclarationMatcher wrapMatcher(const StatementMatcher &Matcher) {
TEST_F(StencilTest, SingleStatement) {
   )cc";
   auto StmtMatch = matchStmt(
       Snippet, ifStmt(hasCondition(expr().bind(Condition)),
                       hasThen(stmt().bind(Then)), hasElse(stmt().bind(Else))));
   ASSERT_TRUE(StmtMatch);
   // Invert the if-then-else.
   auto Stencil = cat("if (!", node(Condition), ") ", statement(Else), " else ",
                      statement(Then));
-  EXPECT_THAT(toOptional(Stencil.eval(StmtMatch->Result)),
-              IsSomething(Eq("if (!true) return 0; else return 1;")));
+  EXPECT_THAT_EXPECTED(Stencil.eval(StmtMatch->Result),
+                       HasValue("if (!true) return 0; else return 1;"));
 }
 
 TEST_F(StencilTest, SingleStatementCallOperator) {
   StringRef Condition("C"), Then("T"), Else("E");
   const std::string Snippet = R"cc(
     if (true)
       return 1;
     else
       return 0;
   )cc";
   auto StmtMatch = matchStmt(
       Snippet, ifStmt(hasCondition(expr().bind(Condition)),
                       hasThen(stmt().bind(Then)), hasElse(stmt().bind(Else))));
   ASSERT_TRUE(StmtMatch);
   // Invert the if-then-else.
   Stencil S = cat("if (!", node(Condition), ") ", statement(Else), " else ",
                   statement(Then));
-  EXPECT_THAT(toOptional(S(StmtMatch->Result)),
-              IsSomething(Eq("if (!true) return 0; else return 1;")));
+  EXPECT_THAT_EXPECTED(S(StmtMatch->Result),
+                       HasValue("if (!true) return 0; else return 1;"));
 }
 
 TEST_F(StencilTest, UnboundNode) {
   const std::string Snippet = R"cc(
     if (true)
       return 1;
     else
       return 0;