[clang-format] In tests, expected code should be format-stable

Summary: Extend various verifyFormat helper functions to check that the
expected text is "stable". This provides some protection against bugs
where formatting results are ocilating between two forms, or continually
change in some other way.

Testing Done:

* Ran unit tests.

* Reproduced a known instability in preprocessor indentation which was
  caught by this new check.

Reviewers: krasimir

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D42034

llvm-svn: 329231

clang/unittests/Format/FormatTest.cpp

@@ -72,6 +72,8 @@ class FormatTest : public ::testing::Test {
 
   void verifyFormat(llvm::StringRef Expected, llvm::StringRef Code,
                     const FormatStyle &Style = getLLVMStyle()) {
+    EXPECT_EQ(Expected.str(), format(Expected, Style))
+        << "Expected code is not stable";
     EXPECT_EQ(Expected.str(), format(Code, Style));
     if (Style.Language == FormatStyle::LK_Cpp) {
       // Objective-C++ is a superset of C++, so everything checked for C++

clang/unittests/Format/FormatTestComments.cpp

@@ -70,6 +70,7 @@ class FormatTestComments : public ::testing::Test {
 
   void verifyFormat(llvm::StringRef Code,
                     const FormatStyle &Style = getLLVMStyle()) {
+    EXPECT_EQ(Code.str(), format(Code, Style)) << "Expected code is not stable";
     EXPECT_EQ(Code.str(), format(test::messUp(Code), Style));
   }
 

clang/unittests/Format/FormatTestJS.cpp

@@ -49,6 +49,8 @@ class FormatTestJS : public ::testing::Test {
   static void verifyFormat(
       llvm::StringRef Code,
       const FormatStyle &Style = getGoogleStyle(FormatStyle::LK_JavaScript)) {
+    EXPECT_EQ(Code.str(), format(Code, Style))
+        << "Expected code is not stable";
     std::string Result = format(test::messUp(Code), Style);
     EXPECT_EQ(Code.str(), Result) << "Formatted:\n" << Result;
   }
@@ -57,6 +59,8 @@ class FormatTestJS : public ::testing::Test {
       llvm::StringRef Expected,
       llvm::StringRef Code,
       const FormatStyle &Style = getGoogleStyle(FormatStyle::LK_JavaScript)) {
+    EXPECT_EQ(Expected.str(), format(Expected, Style))
+        << "Expected code is not stable";
     std::string Result = format(Code, Style);
     EXPECT_EQ(Expected.str(), Result) << "Formatted:\n" << Result;
   }

clang/unittests/Format/FormatTestJava.cpp

@@ -46,6 +46,7 @@ class FormatTestJava : public ::testing::Test {
   static void verifyFormat(
       llvm::StringRef Code,
       const FormatStyle &Style = getGoogleStyle(FormatStyle::LK_Java)) {
+    EXPECT_EQ(Code.str(), format(Code, Style)) << "Expected code is not stable";
     EXPECT_EQ(Code.str(), format(test::messUp(Code), Style));
   }
 };

clang/unittests/Format/FormatTestObjC.cpp

@@ -58,6 +58,7 @@ class FormatTestObjC : public ::testing::Test {
   }
 
   void verifyFormat(StringRef Code) {
+    EXPECT_EQ(Code.str(), format(Code)) << "Expected code is not stable";
     EXPECT_EQ(Code.str(), format(test::messUp(Code)));
   }
 

clang/unittests/Format/FormatTestProto.cpp

@@ -38,6 +38,7 @@ class FormatTestProto : public ::testing::Test {
   }
 
   static void verifyFormat(llvm::StringRef Code) {
+    EXPECT_EQ(Code.str(), format(Code)) << "Expected code is not stable";
     EXPECT_EQ(Code.str(), format(test::messUp(Code)));
   }
 };

clang/unittests/Format/FormatTestTextProto.cpp

@@ -36,6 +36,7 @@ class FormatTestTextProto : public ::testing::Test {
   }
 
   static void verifyFormat(llvm::StringRef Code, const FormatStyle &Style) {
+    EXPECT_EQ(Code.str(), format(Code, Style)) << "Expected code is not stable";
     EXPECT_EQ(Code.str(), format(test::messUp(Code), Style));
   }