[clangd] Verify the diagnostic code in include-fixer diagnostic tests, NFC.

[hokein]

Summary

Make it easier to spot which diagnostics in the include-fixer list are tested.

[kadircet]

LGTM, but can you add some description about why you've decided to do it now :D

[hokein]

In D88828#2311679, @kadircet wrote:

LGTM, but can you add some description about why you've decided to do it now :D

yeah, this comes up when I read the code, I think it is easier to spot which diagnostics in the include-fixer list are tested, (e.g. err_incomplete_type is not tested yet).

And my next step to see whether there are other missing diagnostics that could be fixed by inserting a header.

clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp

auto Index = buildIndexWithSymbol(
       {SymbolWithHeader{"ns::X", "unittest:///x.h", "\"x.h\""}});
   TU.ExternalIndex = Index.get();
 
   EXPECT_THAT(
       TU.build().getDiagnostics(),
       UnorderedElementsAre(
           AllOf(Diag(Test.range("nested"),
                      "incomplete type 'ns::X' named in nested name specifier"),
+                DiagName("incomplete_nested_name_spec"),
                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                             "Add include \"x.h\" for symbol ns::X"))),
           AllOf(Diag(Test.range("base"), "base class has incomplete type"),
+                DiagName("incomplete_base_class"),
                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                             "Add include \"x.h\" for symbol ns::X"))),
           AllOf(Diag(Test.range("access"),
                      "member access into incomplete type 'ns::X'"),
+                DiagName("incomplete_member_access"),
                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                             "Add include \"x.h\" for symbol ns::X")))));
 }
 
 TEST(IncludeFixerTest, NoSuggestIncludeWhenNoDefinitionInHeader) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace ns {
   class X;
auto Index = buildIndexWithSymbol(
       {SymbolWithHeader{"ns::X", "unittest:///x.h", "\"x.h\""},
        SymbolWithHeader{"Global", "unittest:///global.h", "\"global.h\""}});
   TU.ExternalIndex = Index.get();
 
   EXPECT_THAT(
       TU.build().getDiagnostics(),
       UnorderedElementsAre(
           AllOf(Diag(Test.range("unqualified1"), "unknown type name 'X'"),
+                DiagName("unknown_typename"),
                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                             "Add include \"x.h\" for symbol ns::X"))),
           Diag(Test.range("unqualified2"), "use of undeclared identifier 'X'"),
           AllOf(Diag(Test.range("qualified1"),
                      "no type named 'X' in namespace 'ns'"),
+                DiagName("typename_nested_not_found"),
                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                             "Add include \"x.h\" for symbol ns::X"))),
           AllOf(Diag(Test.range("qualified2"),
                      "no member named 'X' in namespace 'ns'"),
+                DiagName("no_member"),
                 WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                             "Add include \"x.h\" for symbol ns::X"))),
           AllOf(Diag(Test.range("global"),
                      "no type named 'Global' in the global namespace"),
+                DiagName("typename_nested_not_found"),
                 WithFix(Fix(Test.range("insert"), "#include \"global.h\"\n",
                             "Add include \"global.h\" for symbol Global")))));
 }
 
 TEST(IncludeFixerTest, MultipleMatchedSymbols) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace na {
 namespace nb {
 void foo() {
   $unqualified[[X]] x;
 }
 }
 }
   )cpp");
   auto TU = TestTU::withCode(Test.code());
   auto Index = buildIndexWithSymbol(
       {SymbolWithHeader{"na::X", "unittest:///a.h", "\"a.h\""},
        SymbolWithHeader{"na::nb::X", "unittest:///b.h", "\"b.h\""}});
   TU.ExternalIndex = Index.get();
 
   EXPECT_THAT(TU.build().getDiagnostics(),
               UnorderedElementsAre(AllOf(
                   Diag(Test.range("unqualified"), "unknown type name 'X'"),
+                  DiagName("unknown_typename"),
                   WithFix(Fix(Test.range("insert"), "#include \"a.h\"\n",
                               "Add include \"a.h\" for symbol na::X"),
                           Fix(Test.range("insert"), "#include \"b.h\"\n",
                               "Add include \"b.h\" for symbol na::nb::X")))));
 }
 
 TEST(IncludeFixerTest, NoCrashMemebrAccess) {
   Annotations Test(R"cpp(// error-ok
void g() {  ns::$[[scope]]::X_Y();  }
   auto Index = buildIndexWithSymbol(
       SymbolWithHeader{"ns::scope::X_Y", "unittest:///x.h", "\"x.h\""});
   TU.ExternalIndex = Index.get();
 
   EXPECT_THAT(
       TU.build().getDiagnostics(),
       UnorderedElementsAre(AllOf(
           Diag(Test.range(), "no member named 'scope' in namespace 'ns'"),
+          DiagName("no_member"),
           WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                       "Add include \"x.h\" for symbol ns::scope::X_Y")))));
 }
 
 TEST(IncludeFixerTest, UnresolvedSpecifierWithSemaCorrection) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace clang {
 void f() {
void f() {
   TU.ExternalIndex = Index.get();
 
   EXPECT_THAT(
       TU.build().getDiagnostics(),
       UnorderedElementsAre(
           AllOf(
               Diag(Test.range("q1"), "use of undeclared identifier 'clangd'; "
                                      "did you mean 'clang'?"),
+              DiagName("undeclared_var_use_suggest"),
               WithFix(_, // change clangd to clang
                       Fix(Test.range("insert"), "#include \"x.h\"\n",
                           "Add include \"x.h\" for symbol clang::clangd::X"))),
           AllOf(
               Diag(Test.range("x"), "no type named 'X' in namespace 'clang'"),
+              DiagName("typename_nested_not_found"),
               WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                           "Add include \"x.h\" for symbol clang::clangd::X"))),
           AllOf(
               Diag(Test.range("q2"), "use of undeclared identifier 'clangd'; "
                                      "did you mean 'clang'?"),
+              DiagName("undeclared_var_use_suggest"),
               WithFix(
-                  _, // change clangd to clangd
+                  _, // change clangd to clang
                   Fix(Test.range("insert"), "#include \"y.h\"\n",
                       "Add include \"y.h\" for symbol clang::clangd::ns::Y"))),
           AllOf(Diag(Test.range("ns"),
                      "no member named 'ns' in namespace 'clang'"),
+                DiagName("no_member"),
                 WithFix(Fix(
                     Test.range("insert"), "#include \"y.h\"\n",
                     "Add include \"y.h\" for symbol clang::clangd::ns::Y")))));
 }
 
 TEST(IncludeFixerTest, SpecifiedScopeIsNamespaceAlias) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace a {}
 namespace b = a;
 namespace c {
   b::$[[X]] x;
 }
   )cpp");
   auto TU = TestTU::withCode(Test.code());
   auto Index = buildIndexWithSymbol(
       SymbolWithHeader{"a::X", "unittest:///x.h", "\"x.h\""});
   TU.ExternalIndex = Index.get();
 
   EXPECT_THAT(TU.build().getDiagnostics(),
               UnorderedElementsAre(AllOf(
                   Diag(Test.range(), "no type named 'X' in namespace 'a'"),
+                  DiagName("typename_nested_not_found"),
                   WithFix(Fix(Test.range("insert"), "#include \"x.h\"\n",
                               "Add include \"x.h\" for symbol a::X")))));
 }
 
 TEST(IncludeFixerTest, NoCrashOnTemplateInstantiations) {
   Annotations Test(R"cpp(
     template <typename T> struct Templ {
       template <typename U>