diff --git a/clang-tools-extra/clangd/Config.h b/clang-tools-extra/clangd/Config.h
--- a/clang-tools-extra/clangd/Config.h
+++ b/clang-tools-extra/clangd/Config.h
@@ -109,7 +109,7 @@
     bool AllowStalePreamble = false;
 
     IncludesPolicy UnusedIncludes = IncludesPolicy::Strict;
-    IncludesPolicy MissingIncludes = IncludesPolicy::None;
+    IncludesPolicy MissingIncludes = IncludesPolicy::Strict;
 
     /// IncludeCleaner will not diagnose usages of these headers matched by
     /// these regexes.
diff --git a/clang-tools-extra/clangd/unittests/ClangdTests.cpp b/clang-tools-extra/clangd/unittests/ClangdTests.cpp
--- a/clang-tools-extra/clangd/unittests/ClangdTests.cpp
+++ b/clang-tools-extra/clangd/unittests/ClangdTests.cpp
@@ -11,6 +11,7 @@
 #include "CodeComplete.h"
 #include "CompileCommands.h"
 #include "ConfigFragment.h"
+#include "Diagnostics.h"
 #include "GlobalCompilationDatabase.h"
 #include "Matchers.h"
 #include "SyncAPI.h"
@@ -1205,8 +1206,13 @@
   public:
     void onDiagnosticsReady(PathRef File, llvm::StringRef Version,
                             std::vector<Diag> Diagnostics) override {
+      bool HasTidyDiags = false;
+      for (auto &D : Diagnostics) {
+        if (D.Source == Diag::ClangTidy)
+          HasTidyDiags = true;
+      }
       std::lock_guard<std::mutex> Lock(Mutex);
-      HadDiagsInLastCallback = !Diagnostics.empty();
+      HadDiagsInLastCallback = HasTidyDiags;
     }
 
     std::mutex Mutex;
diff --git a/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp b/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp
--- a/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp
+++ b/clang-tools-extra/clangd/unittests/DiagnosticsTests.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "/usr/local/google/home/kadircet/repos/llvm/clang-tools-extra/clang-tidy/ClangTidyOptions.h"
+#include "../clang-tidy/ClangTidyOptions.h"
 #include "Annotations.h"
 #include "Config.h"
 #include "Diagnostics.h"
@@ -38,6 +38,7 @@
 #include "gtest/gtest.h"
 #include <cstddef>
 #include <memory>
+#include <optional>
 #include <string>
 #include <utility>
 #include <vector>
@@ -150,7 +151,17 @@
   return M;
 }
 
-TEST(DiagnosticsTest, DiagnosticRanges) {
+class DiagnosticsTest : public ::testing::Test {
+  std::optional<WithContextValue> Ctx;
+  void SetUp() override {
+    Config Cfg;
+    Cfg.Diagnostics.MissingIncludes = Config::IncludesPolicy::None;
+    Cfg.Diagnostics.UnusedIncludes = Config::IncludesPolicy::None;
+    Ctx.emplace(Config::Key, std::move(Cfg));
+  }
+};
+
+TEST_F(DiagnosticsTest, DiagnosticRanges) {
   // Check we report correct ranges, including various edge-cases.
   Annotations Test(R"cpp(
     // error-ok
@@ -214,7 +225,7 @@
 // fires for the full expression range (see tweaks/PopulateSwitchTests.cpp).
 // The quickfix flow only works end-to-end if the tweak can be triggered on
 // the diagnostic's range.
-TEST(DiagnosticsTest, WSwitch) {
+TEST_F(DiagnosticsTest, WSwitch) {
   Annotations Test(R"cpp(
     enum A { X };
     struct B { A a; };
@@ -229,7 +240,7 @@
                                "enumeration value 'X' not handled in switch")));
 }
 
-TEST(DiagnosticsTest, FlagsMatter) {
+TEST_F(DiagnosticsTest, FlagsMatter) {
   Annotations Test("[[void]] main() {} // error-ok");
   auto TU = TestTU::withCode(Test.code());
   EXPECT_THAT(*TU.build().getDiagnostics(),
@@ -245,7 +256,7 @@
           withFix(Fix(Test.range(), "int", "change return type to 'int'")))));
 }
 
-TEST(DiagnosticsTest, DiagnosticPreamble) {
+TEST_F(DiagnosticsTest, DiagnosticPreamble) {
   Annotations Test(R"cpp(
     #include $[["not-found.h"]] // error-ok
   )cpp");
@@ -257,7 +268,7 @@
                   diagSource(Diag::Clang), diagName("pp_file_not_found"))));
 }
 
-TEST(DiagnosticsTest, DeduplicatedClangTidyDiagnostics) {
+TEST_F(DiagnosticsTest, DeduplicatedClangTidyDiagnostics) {
   Annotations Test(R"cpp(
     float foo = [[0.1f]];
   )cpp");
@@ -295,7 +306,7 @@
           diagSource(Diag::ClangTidy)))));
 }
 
-TEST(DiagnosticsTest, ClangTidy) {
+TEST_F(DiagnosticsTest, ClangTidy) {
   Annotations Test(R"cpp(
     #include $deprecated[["assert.h"]]
 
@@ -356,7 +367,7 @@
                "function 'bar' is within a recursive call chain"))));
 }
 
-TEST(DiagnosticsTest, ClangTidyEOF) {
+TEST_F(DiagnosticsTest, ClangTidyEOF) {
   // clang-format off
   Annotations Test(R"cpp(
   [[#]]include <b.h>
@@ -373,7 +384,7 @@
                 diagSource(Diag::ClangTidy), diagName("llvm-include-order")))));
 }
 
-TEST(DiagnosticTest, TemplatesInHeaders) {
+TEST_F(DiagnosticsTest, TemplatesInHeaders) {
   // Diagnostics from templates defined in headers are placed at the expansion.
   Annotations Main(R"cpp(
     Derived<int> [[y]]; // error-ok
@@ -393,7 +404,7 @@
                                       "'Derived<int>' requested here")))));
 }
 
-TEST(DiagnosticTest, MakeUnique) {
+TEST_F(DiagnosticsTest, MakeUnique) {
   // We usually miss diagnostics from header functions as we don't parse them.
   // std::make_unique is an exception.
   Annotations Main(R"cpp(
@@ -418,7 +429,7 @@
                        "no matching constructor for initialization of 'S'")));
 }
 
-TEST(DiagnosticTest, MakeShared) {
+TEST_F(DiagnosticsTest, MakeShared) {
   // We usually miss diagnostics from header functions as we don't parse them.
   // std::make_shared is only parsed when --parse-forwarding-functions is set
   Annotations Main(R"cpp(
@@ -444,7 +455,7 @@
                        "no matching constructor for initialization of 'S'")));
 }
 
-TEST(DiagnosticTest, NoMultipleDiagnosticInFlight) {
+TEST_F(DiagnosticsTest, NoMultipleDiagnosticInFlight) {
   Annotations Main(R"cpp(
     template <typename T> struct Foo {
       T *begin();
@@ -471,7 +482,7 @@
           diagSource(Diag::ClangTidy), diagName("modernize-loop-convert")))));
 }
 
-TEST(DiagnosticTest, RespectsDiagnosticConfig) {
+TEST_F(DiagnosticsTest, RespectsDiagnosticConfig) {
   Annotations Main(R"cpp(
     // error-ok
     void x() {
@@ -493,7 +504,7 @@
                                "use of undeclared identifier 'unknown'")));
 }
 
-TEST(DiagnosticTest, RespectsDiagnosticConfigInHeader) {
+TEST_F(DiagnosticsTest, RespectsDiagnosticConfigInHeader) {
   Annotations Header(R"cpp(
     int x = "42";  // error-ok
   )cpp");
@@ -508,7 +519,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), IsEmpty());
 }
 
-TEST(DiagnosticTest, ClangTidySuppressionComment) {
+TEST_F(DiagnosticsTest, ClangTidySuppressionComment) {
   Annotations Main(R"cpp(
     int main() {
       int i = 3;
@@ -540,7 +551,7 @@
           diagName("bugprone-integer-division")))));
 }
 
-TEST(DiagnosticTest, ClangTidySystemMacro) {
+TEST_F(DiagnosticsTest, ClangTidySystemMacro) {
   Annotations Main(R"cpp(
     #include "user.h"
     #include "system.h"
@@ -571,7 +582,7 @@
                                        Diag(Main.range("user"), BadDivision))));
 }
 
-TEST(DiagnosticTest, ClangTidyWarningAsError) {
+TEST_F(DiagnosticsTest, ClangTidyWarningAsError) {
   Annotations Main(R"cpp(
     int main() {
       int i = 3;
@@ -603,7 +614,7 @@
   };
 }
 
-TEST(DiagnosticTest, ClangTidyEnablesClangWarning) {
+TEST_F(DiagnosticsTest, ClangTidyEnablesClangWarning) {
   Annotations Main(R"cpp( // error-ok
     static void [[foo]]() {}
   )cpp");
@@ -692,7 +703,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), IsEmpty());
 }
 
-TEST(DiagnosticTest, LongFixMessages) {
+TEST_F(DiagnosticsTest, LongFixMessages) {
   // We limit the size of printed code.
   Annotations Source(R"cpp(
     int main() {
@@ -724,7 +735,7 @@
                   Fix(Source.range(), "ident", "change 'ide\\…' to 'ident'"))));
 }
 
-TEST(DiagnosticTest, NewLineFixMessage) {
+TEST_F(DiagnosticsTest, NewLineFixMessage) {
   Annotations Source("int a;[[]]");
   TestTU TU = TestTU::withCode(Source.code());
   TU.ExtraArgs = {"-Wnewline-eof"};
@@ -733,7 +744,7 @@
       ElementsAre(withFix((Fix(Source.range(), "\n", "insert '\\n'")))));
 }
 
-TEST(DiagnosticTest, ClangTidySuppressionCommentTrumpsWarningAsError) {
+TEST_F(DiagnosticsTest, ClangTidySuppressionCommentTrumpsWarningAsError) {
   Annotations Main(R"cpp(
     int main() {
       int i = 3;
@@ -746,7 +757,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), UnorderedElementsAre());
 }
 
-TEST(DiagnosticTest, ClangTidyNoLiteralDataInMacroToken) {
+TEST_F(DiagnosticsTest, ClangTidyNoLiteralDataInMacroToken) {
   Annotations Main(R"cpp(
     #define SIGTERM 15
     using pthread_t = int;
@@ -761,7 +772,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), UnorderedElementsAre()); // no-crash
 }
 
-TEST(DiagnosticTest, ElseAfterReturnRange) {
+TEST_F(DiagnosticsTest, ElseAfterReturnRange) {
   Annotations Main(R"cpp(
     int foo(int cond) {
     if (cond == 1) {
@@ -779,7 +790,7 @@
                   Diag(Main.range(), "do not use 'else' after 'return'"))));
 }
 
-TEST(DiagnosticTest, ClangTidySelfContainedDiags) {
+TEST_F(DiagnosticsTest, ClangTidySelfContainedDiags) {
   Annotations Main(R"cpp($MathHeader[[]]
     struct Foo{
       int A, B;
@@ -840,7 +851,7 @@
                 withFix(equalToFix(ExpectedDFix))))));
 }
 
-TEST(DiagnosticsTest, Preprocessor) {
+TEST_F(DiagnosticsTest, Preprocessor) {
   // This looks like a preamble, but there's an #else in the middle!
   // Check that:
   //  - the #else doesn't generate diagnostics (we had this bug)
@@ -859,7 +870,7 @@
       ElementsAre(Diag(Test.range(), "use of undeclared identifier 'b'")));
 }
 
-TEST(DiagnosticsTest, IgnoreVerify) {
+TEST_F(DiagnosticsTest, IgnoreVerify) {
   auto TU = TestTU::withCode(R"cpp(
     int a; // expected-error {{}}
   )cpp");
@@ -868,7 +879,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), IsEmpty());
 }
 
-TEST(DiagnosticTest, IgnoreBEFilelistOptions) {
+TEST_F(DiagnosticsTest, IgnoreBEFilelistOptions) {
   auto TU = TestTU::withCode("");
   TU.ExtraArgs.push_back("-Xclang");
   for (const auto *DisableOption :
@@ -882,7 +893,7 @@
 }
 
 // Recursive main-file include is diagnosed, and doesn't crash.
-TEST(DiagnosticsTest, RecursivePreamble) {
+TEST_F(DiagnosticsTest, RecursivePreamble) {
   auto TU = TestTU::withCode(R"cpp(
     #include "foo.h" // error-ok
     int symbol;
@@ -894,7 +905,7 @@
 }
 
 // Recursive main-file include with #pragma once guard is OK.
-TEST(DiagnosticsTest, RecursivePreamblePragmaOnce) {
+TEST_F(DiagnosticsTest, RecursivePreamblePragmaOnce) {
   auto TU = TestTU::withCode(R"cpp(
     #pragma once
     #include "foo.h"
@@ -908,7 +919,7 @@
 
 // Recursive main-file include with #ifndef guard should be OK.
 // However, it's not yet recognized (incomplete at end of preamble).
-TEST(DiagnosticsTest, RecursivePreambleIfndefGuard) {
+TEST_F(DiagnosticsTest, RecursivePreambleIfndefGuard) {
   auto TU = TestTU::withCode(R"cpp(
     #ifndef FOO
     #define FOO
@@ -923,7 +934,7 @@
   EXPECT_THAT(TU.build().getLocalTopLevelDecls(), SizeIs(1));
 }
 
-TEST(DiagnosticsTest, PreambleWithPragmaAssumeNonnull) {
+TEST_F(DiagnosticsTest, PreambleWithPragmaAssumeNonnull) {
   auto TU = TestTU::withCode(R"cpp(
 #pragma clang assume_nonnull begin
 void foo(int *x);
@@ -936,7 +947,7 @@
               NullabilityKind::NonNull);
 }
 
-TEST(DiagnosticsTest, PreambleHeaderWithBadPragmaAssumeNonnull) {
+TEST_F(DiagnosticsTest, PreambleHeaderWithBadPragmaAssumeNonnull) {
   Annotations Header(R"cpp(
 #pragma clang assume_nonnull begin  // error-ok
 void foo(int *X);
@@ -956,7 +967,7 @@
   ASSERT_FALSE(Y->getOriginalType()->getNullability());
 }
 
-TEST(DiagnosticsTest, InsideMacros) {
+TEST_F(DiagnosticsTest, InsideMacros) {
   Annotations Test(R"cpp(
     #define TEN 10
     #define RET(x) return x + 10
@@ -977,7 +988,7 @@
                                "'int *' with an rvalue of type 'int'")));
 }
 
-TEST(DiagnosticsTest, NoFixItInMacro) {
+TEST_F(DiagnosticsTest, NoFixItInMacro) {
   Annotations Test(R"cpp(
     #define Define(name) void name() {}
 
@@ -989,7 +1000,7 @@
                                 Not(withFix(_)))));
 }
 
-TEST(DiagnosticsTest, PragmaSystemHeader) {
+TEST_F(DiagnosticsTest, PragmaSystemHeader) {
   Annotations Test("#pragma clang [[system_header]]\n");
   auto TU = TestTU::withCode(Test.code());
   EXPECT_THAT(
@@ -1000,7 +1011,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), IsEmpty());
 }
 
-TEST(ClangdTest, MSAsm) {
+TEST_F(DiagnosticsTest, MSAsm) {
   // Parsing MS assembly tries to use the target MCAsmInfo, which we don't link.
   // We used to crash here. Now clang emits a diagnostic, which we filter out.
   llvm::InitializeAllTargetInfos(); // As in ClangdMain
@@ -1009,7 +1020,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), IsEmpty());
 }
 
-TEST(DiagnosticsTest, ToLSP) {
+TEST_F(DiagnosticsTest, ToLSP) {
   URIForFile MainFile =
       URIForFile::canonicalize(testPath("foo/bar/main.cpp"), "");
   URIForFile HeaderFile =
@@ -1137,7 +1148,7 @@
   return MemIndex::build(std::move(Slab).build(), RefSlab(), RelationSlab());
 }
 
-TEST(IncludeFixerTest, IncompleteType) {
+TEST_F(DiagnosticsTest, IncludeFixerIncompleteType) {
   auto TU = TestTU::withHeaderCode("namespace ns { class X; } ns::X *x;");
   TU.ExtraArgs.push_back("-std=c++20");
   auto Index = buildIndexWithSymbol(
@@ -1185,7 +1196,7 @@
   }
 }
 
-TEST(IncludeFixerTest, IncompleteEnum) {
+TEST_F(DiagnosticsTest, IncludeFixerIncompleteEnum) {
   Symbol Sym = enm("X");
   Sym.Flags |= Symbol::IndexedForCodeCompletion;
   Sym.CanonicalDeclaration.FileURI = Sym.Definition.FileURI = "unittest:///x.h";
@@ -1216,7 +1227,7 @@
   }
 }
 
-TEST(IncludeFixerTest, NoSuggestIncludeWhenNoDefinitionInHeader) {
+TEST_F(DiagnosticsTest, IncludeFixerNoSuggestIncludeWhenNoDefinitionInHeader) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace ns {
   class X;
@@ -1247,7 +1258,7 @@
                        "member access into incomplete type 'ns::X'")));
 }
 
-TEST(IncludeFixerTest, Typo) {
+TEST_F(DiagnosticsTest, IncludeFixerTypo) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace ns {
 void foo() {
@@ -1307,7 +1318,7 @@
                             "Include \"x.h\" for symbol ns::X")))));
 }
 
-TEST(IncludeFixerTest, TypoInMacro) {
+TEST_F(DiagnosticsTest, IncludeFixerTypoInMacro) {
   auto TU = TestTU::withCode(R"cpp(// error-ok
 #define ID(T) T
 X a1;
@@ -1328,7 +1339,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), Each(withFix(_)));
 }
 
-TEST(IncludeFixerTest, MultipleMatchedSymbols) {
+TEST_F(DiagnosticsTest, IncludeFixerMultipleMatchedSymbols) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace na {
 namespace nb {
@@ -1354,7 +1365,7 @@
                               "Include \"b.h\" for symbol na::nb::X")))));
 }
 
-TEST(IncludeFixerTest, NoCrashMemberAccess) {
+TEST_F(DiagnosticsTest, IncludeFixerNoCrashMemberAccess) {
   Annotations Test(R"cpp(// error-ok
     struct X { int  xyz; };
     void g() { X x; x.$[[xy]]; }
@@ -1369,7 +1380,7 @@
       UnorderedElementsAre(Diag(Test.range(), "no member named 'xy' in 'X'")));
 }
 
-TEST(IncludeFixerTest, UseCachedIndexResults) {
+TEST_F(DiagnosticsTest, IncludeFixerUseCachedIndexResults) {
   // As index results for the identical request are cached, more than 5 fixes
   // are generated.
   Annotations Test(R"cpp(// error-ok
@@ -1409,7 +1420,7 @@
   }
 }
 
-TEST(IncludeFixerTest, UnresolvedNameAsSpecifier) {
+TEST_F(DiagnosticsTest, IncludeFixerUnresolvedNameAsSpecifier) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace ns {
 }
@@ -1432,7 +1443,7 @@
                             "Include \"x.h\" for symbol ns::scope::X_Y")))));
 }
 
-TEST(IncludeFixerTest, UnresolvedSpecifierWithSemaCorrection) {
+TEST_F(DiagnosticsTest, IncludeFixerUnresolvedSpecifierWithSemaCorrection) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace clang {
 void f() {
@@ -1479,7 +1490,7 @@
                         "Include \"y.h\" for symbol clang::clangd::ns::Y")))));
 }
 
-TEST(IncludeFixerTest, SpecifiedScopeIsNamespaceAlias) {
+TEST_F(DiagnosticsTest, IncludeFixerSpecifiedScopeIsNamespaceAlias) {
   Annotations Test(R"cpp(// error-ok
 $insert[[]]namespace a {}
 namespace b = a;
@@ -1500,7 +1511,7 @@
                               "Include \"x.h\" for symbol a::X")))));
 }
 
-TEST(IncludeFixerTest, NoCrashOnTemplateInstantiations) {
+TEST_F(DiagnosticsTest, IncludeFixerNoCrashOnTemplateInstantiations) {
   Annotations Test(R"cpp(
     template <typename T> struct Templ {
       template <typename U>
@@ -1522,7 +1533,7 @@
       ElementsAre(Diag(Test.range(), "use of undeclared identifier 'a'")));
 }
 
-TEST(IncludeFixerTest, HeaderNamedInDiag) {
+TEST_F(DiagnosticsTest, IncludeFixerHeaderNamedInDiag) {
   Annotations Test(R"cpp(
     $insert[[]]int main() {
       [[printf]]("");
@@ -1554,7 +1565,7 @@
                       "Include <stdio.h> for symbol printf")))));
 }
 
-TEST(IncludeFixerTest, CImplicitFunctionDecl) {
+TEST_F(DiagnosticsTest, IncludeFixerCImplicitFunctionDecl) {
   Annotations Test("void x() { [[foo]](); }");
   auto TU = TestTU::withCode(Test.code());
   TU.Filename = "test.c";
@@ -1588,7 +1599,7 @@
                               "Include \"foo.h\" for symbol foo")))));
 }
 
-TEST(DiagsInHeaders, DiagInsideHeader) {
+TEST_F(DiagnosticsTest, DiagInsideHeader) {
   Annotations Main(R"cpp(
     #include [["a.h"]]
     void foo() {})cpp");
@@ -1602,7 +1613,7 @@
                   withNote(Diag(Header.range(), "error occurred here")))));
 }
 
-TEST(DiagsInHeaders, DiagInTransitiveInclude) {
+TEST_F(DiagnosticsTest, DiagInTransitiveInclude) {
   Annotations Main(R"cpp(
     #include [["a.h"]]
     void foo() {})cpp");
@@ -1615,7 +1626,7 @@
                                         "required for all declarations")));
 }
 
-TEST(DiagsInHeaders, DiagInMultipleHeaders) {
+TEST_F(DiagnosticsTest, DiagInMultipleHeaders) {
   Annotations Main(R"cpp(
     #include $a[["a.h"]]
     #include $b[["b.h"]]
@@ -1631,7 +1642,7 @@
                                         "required for all declarations")));
 }
 
-TEST(DiagsInHeaders, PreferExpansionLocation) {
+TEST_F(DiagnosticsTest, PreferExpansionLocation) {
   Annotations Main(R"cpp(
     #include [["a.h"]]
     #include "b.h"
@@ -1645,7 +1656,7 @@
                                           "is required for all declarations")));
 }
 
-TEST(DiagsInHeaders, PreferExpansionLocationMacros) {
+TEST_F(DiagnosticsTest, PreferExpansionLocationMacros) {
   Annotations Main(R"cpp(
     #define X
     #include "a.h"
@@ -1663,7 +1674,7 @@
                                         "required for all declarations")));
 }
 
-TEST(DiagsInHeaders, LimitDiagsOutsideMainFile) {
+TEST_F(DiagnosticsTest, LimitDiagsOutsideMainFile) {
   Annotations Main(R"cpp(
     #include [["a.h"]]
     #include "b.h"
@@ -1692,7 +1703,7 @@
                                         "required for all declarations")));
 }
 
-TEST(DiagsInHeaders, OnlyErrorOrFatal) {
+TEST_F(DiagnosticsTest, OnlyErrorOrFatal) {
   Annotations Main(R"cpp(
     #include [["a.h"]]
     void foo() {})cpp");
@@ -1708,7 +1719,7 @@
                   withNote(Diag(Header.range(), "error occurred here")))));
 }
 
-TEST(DiagsInHeaders, OnlyDefaultErrorOrFatal) {
+TEST_F(DiagnosticsTest, OnlyDefaultErrorOrFatal) {
   Annotations Main(R"cpp(
     #include [["a.h"]] // get unused "foo" warning when building preamble.
     )cpp");
@@ -1722,7 +1733,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), IsEmpty());
 }
 
-TEST(DiagsInHeaders, FromNonWrittenSources) {
+TEST_F(DiagnosticsTest, FromNonWrittenSources) {
   Annotations Main(R"cpp(
     #include [["a.h"]]
     void foo() {})cpp");
@@ -1739,7 +1750,7 @@
                   withNote(Diag(Header.range(), "error occurred here")))));
 }
 
-TEST(DiagsInHeaders, ErrorFromMacroExpansion) {
+TEST_F(DiagnosticsTest, ErrorFromMacroExpansion) {
   Annotations Main(R"cpp(
   void bar() {
     int fo; // error-ok
@@ -1756,7 +1767,7 @@
                                      "identifier 'foo'; did you mean 'fo'?")));
 }
 
-TEST(DiagsInHeaders, ErrorFromMacroArgument) {
+TEST_F(DiagnosticsTest, ErrorFromMacroArgument) {
   Annotations Main(R"cpp(
   void bar() {
     int fo; // error-ok
@@ -1773,7 +1784,7 @@
                                      "identifier 'foo'; did you mean 'fo'?")));
 }
 
-TEST(IgnoreDiags, FromNonWrittenInclude) {
+TEST_F(DiagnosticsTest, FromNonWrittenInclude) {
   TestTU TU;
   TU.ExtraArgs.push_back("--include=a.h");
   TU.AdditionalFiles = {{"a.h", "void main();"}};
@@ -1782,7 +1793,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), UnorderedElementsAre());
 }
 
-TEST(ToLSPDiag, RangeIsInMain) {
+TEST_F(DiagnosticsTest, RangeIsInMain) {
   ClangdDiagnosticOptions Opts;
   clangd::Diag D;
   D.Range = {pos(1, 2), pos(3, 4)};
@@ -1805,7 +1816,7 @@
              });
 }
 
-TEST(ParsedASTTest, ModuleSawDiag) {
+TEST_F(DiagnosticsTest, ModuleSawDiag) {
   static constexpr const llvm::StringLiteral KDiagMsg = "StampedDiag";
   struct DiagModifierModule final : public FeatureModule {
     struct Listener : public FeatureModule::ASTListener {
@@ -1831,7 +1842,7 @@
               testing::Contains(Diag(Code.range(), KDiagMsg.str())));
 }
 
-TEST(Preamble, EndsOnNonEmptyLine) {
+TEST_F(DiagnosticsTest, EndsOnNonEmptyLine) {
   TestTU TU;
   TU.ExtraArgs = {"-Wnewline-eof"};
 
@@ -1850,7 +1861,7 @@
   }
 }
 
-TEST(Diagnostics, Tags) {
+TEST_F(DiagnosticsTest, Tags) {
   TestTU TU;
   TU.ExtraArgs = {"-Wunused", "-Wdeprecated"};
   Annotations Test(R"cpp(
@@ -1879,7 +1890,7 @@
                 withTag(DiagnosticTag::Deprecated)))));
 }
 
-TEST(DiagnosticsTest, IncludeCleaner) {
+TEST_F(DiagnosticsTest, IncludeCleaner) {
   Annotations Test(R"cpp(
 $fix[[  $diag[[#include "unused.h"]]
 ]]
@@ -1935,7 +1946,7 @@
   EXPECT_THAT(*TU.build().getDiagnostics(), IsEmpty());
 }
 
-TEST(DiagnosticsTest, FixItFromHeader) {
+TEST_F(DiagnosticsTest, FixItFromHeader) {
   llvm::StringLiteral Header(R"cpp(
     void foo(int *);
     void foo(int *, int);)cpp");
@@ -1958,7 +1969,7 @@
                       "the argument with &")))));
 }
 
-TEST(DiagnosticsTest, UnusedInHeader) {
+TEST_F(DiagnosticsTest, UnusedInHeader) {
   // Clang diagnoses unused static inline functions outside headers.
   auto TU = TestTU::withCode("static inline void foo(void) {}");
   TU.ExtraArgs.push_back("-Wunused-function");