[clangd] Fix parseNamespaceEvents to parse the last token

[hokein]

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

429

could you also add an "empty string" test case?

[kadircet]

• Add empty string testcase

clang-tools-extra/clangd/SourceCode.cpp

static void lex(llvm::StringRef Code, const format::FormatStyle &Style,
   SourceManagerForFile FileSM("dummy.cpp", NullTerminatedCode);
   auto &SM = FileSM.get();
   auto FID = SM.getMainFileID();
   Lexer Lex(FID, SM.getBuffer(FID), SM, format::getFormattingLangOpts(Style));
   Token Tok;
 
   while (!Lex.LexFromRawLexer(Tok))
     A(Tok);
+  // LexFromRawLexer returns true after it lexes last token, so we still have
+  // one more token to report.
+  A(Tok);
 }
 
 llvm::StringMap<unsigned> collectIdentifiers(llvm::StringRef Content,
                                              const format::FormatStyle &Style) {
   llvm::StringMap<unsigned> Identifiers;
   lex(Content, Style, [&](const clang::Token &Tok) {
     switch (Tok.getKind()) {
     case tok::identifier:

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

std::vector<std::pair<const char *, std::vector<std::string>>> Cases = {
             namespace foo{}
             }}}
             namespace bar{
           )cpp",
           {"bar", ""},
       },
       {
           R"cpp(
+            // Parse until EOF
+            namespace bar{})cpp",
+          {""},
+      },
+      {
+          R"cpp(
             // Namespaces with multiple chunks.
             namespace a::b {
               using namespace c::d;
               namespace e::f {
           )cpp",
           {
               "a::b::e::f",
               "",