[clang-format] Set of unit test to begin to validate that we don't change defaults

[MyDeveloperDay]

Summary

This revision is to complement D75791: [clang-format] Added new option IndentExternBlock so we can be sure that we don't change any default behavior.

For now just add rules to cover AfterExternBlock, but in the future we should add cases to cover the other BraceWrapping rules for each style. This will help guard us when we change code inside of the various getXXXStyle() functions to ensure we are not breaking everyone.

[JakeMerdichAMD]

+1 for this idea. It'd eventually be neat to also take all samples from the style guide of each project and test them, if there aren't licensing concerns.

LGTM with an appropriate merge fix/CI passing.

[MarcusJohnson91]

LGTM

[JakeMerdichAMD]

Just belatedly caught something: Webkit style is supported too but not listed here. Can you add that?

[MyDeveloperDay]

Adding WebKitStyle()

[JakeMerdichAMD]

LGTM

[MyDeveloperDay]

I think we should take these tests now once they are landed, and we can begin to flesh them out with for() , do(), while() if() conditions so we always know we are not breaking the default style.

clang/unittests/Format/FormatTest.cpp

verifyFormat("if (argc > 5) [[unlikely]] {\n"
                "} else if (argc > 10) [[likely]] {\n"
                "  return 99;\n"
                "} else {\n"
                "  return 42;\n"
                "}\n",
                Style);
 }
 
+TEST_F(FormatTest, LLVMDefaultStyle) {
+  FormatStyle Style = getLLVMStyle();
+  verifyFormat("extern \"C\" {\n"
+               "int foo();\n"
+               "}",
+               Style);
+}
+TEST_F(FormatTest, GNUDefaultStyle) {
+  FormatStyle Style = getGNUStyle();
+  verifyFormat("extern \"C\"\n"
+               "{\n"
+               "  int foo ();\n"
+               "}",
+               Style);
+}
+TEST_F(FormatTest, MozillaDefaultStyle) {
+  FormatStyle Style = getMozillaStyle();
+  verifyFormat("extern \"C\"\n"
+               "{\n"
+               "  int foo();\n"
+               "}",
+               Style);
+}
+TEST_F(FormatTest, GoogleDefaultStyle) {
+  FormatStyle Style = getGoogleStyle();
+  verifyFormat("extern \"C\" {\n"
+               "int foo();\n"
+               "}",
+               Style);
+}
+TEST_F(FormatTest, ChromiumDefaultStyle) {
+  FormatStyle Style = getChromiumStyle(FormatStyle::LanguageKind::LK_Cpp);
+  verifyFormat("extern \"C\" {\n"
+               "int foo();\n"
+               "}",
+               Style);
+}
+TEST_F(FormatTest, MicrosoftDefaultStyle) {
+  FormatStyle Style = getMicrosoftStyle(FormatStyle::LanguageKind::LK_Cpp);
+  verifyFormat("extern \"C\"\n"
+               "{\n"
+               "    int foo();\n"
+               "}",
+               Style);
+}
+TEST_F(FormatTest, WebKitDefaultStyle) {
+  FormatStyle Style = getWebKitStyle();
+  verifyFormat("extern \"C\" {\n"
+               "int foo();\n"
+               "}",
+               Style);
+}
 } // namespace
 } // namespace format
 } // namespace clang