diff --git a/clang/unittests/Basic/SarifTest.cpp b/clang/unittests/Basic/SarifTest.cpp
--- a/clang/unittests/Basic/SarifTest.cpp
+++ b/clang/unittests/Basic/SarifTest.cpp
@@ -226,7 +226,7 @@
 TEST_F(SarifDocumentWriterTest, checkSerializingArtifacts) {
   // GIVEN:
   const std::string ExpectedOutput =
-      R"({"$schema":"https://docs.oasis-open.org/sarif/sarif/v2.1.0/cos02/schemas/sarif-schema-2.1.0.json","runs":[{"artifacts":[{"length":40,"location":{"index":0,"uri":"file:///main.cpp"},"mimeType":"text/plain","roles":["resultFile"]}],"columnKind":"unicodeCodePoints","results":[{"locations":[{"physicalLocation":{"artifactLocation":{"index":0},"region":{"endColumn":14,"startColumn":14,"startLine":3}}}],"message":{"text":"expected ';' after top level declarator"},"ruleId":"clang.unittest","ruleIndex":0}],"tool":{"driver":{"fullName":"sarif test runner","informationUri":"https://clang.llvm.org/docs/UsersManual.html","language":"en-US","name":"sarif test","rules":[{"fullDescription":{"text":"Example rule created during unit tests"},"id":"clang.unittest","name":"clang unit test"}],"version":"1.0.0"}}}],"version":"2.1.0"})";
+      R"({"$schema":"https://docs.oasis-open.org/sarif/sarif/v2.1.0/cos02/schemas/sarif-schema-2.1.0.json","runs":[{"artifacts":[{"length":40,"location":{"index":0,"uri":"file:///main.cpp"},"mimeType":"text/plain","roles":["resultFile"]}],"columnKind":"unicodeCodePoints","results":[{"level":"error","locations":[{"physicalLocation":{"artifactLocation":{"index":0},"region":{"endColumn":14,"startColumn":14,"startLine":3}}}],"message":{"text":"expected ';' after top level declarator"},"ruleId":"clang.unittest","ruleIndex":0}],"tool":{"driver":{"fullName":"sarif test runner","informationUri":"https://clang.llvm.org/docs/UsersManual.html","language":"en-US","name":"sarif test","rules":[{"fullDescription":{"text":"Example rule created during unit tests"},"id":"clang.unittest","name":"clang unit test"}],"version":"1.0.0"}}}],"version":"2.1.0"})";
 
   SarifDocumentWriter Writer{SourceMgr};
   const SarifRule &Rule =
@@ -252,8 +252,10 @@
   DiagLocs.push_back(SourceCSR);
 
   const SarifResult &Result =
-      SarifResult::create(RuleIdx).setLocations(DiagLocs).setDiagnosticMessage(
-          "expected ';' after top level declarator");
+      SarifResult::create(RuleIdx)
+          .setLocations(DiagLocs)
+          .setDiagnosticMessage("expected ';' after top level declarator")
+          .setDiagnosticLevel(SarifResultLevel::Error);
   Writer.appendResult(Result);
   std::string Output = serializeSarifDocument(Writer.createDocument());
 
@@ -264,7 +266,7 @@
 TEST_F(SarifDocumentWriterTest, checkSerializingCodeflows) {
   // GIVEN:
   const std::string ExpectedOutput =
-      R"({"$schema":"https://docs.oasis-open.org/sarif/sarif/v2.1.0/cos02/schemas/sarif-schema-2.1.0.json","runs":[{"artifacts":[{"length":27,"location":{"index":1,"uri":"file:///test-header-1.h"},"mimeType":"text/plain","roles":["resultFile"]},{"length":30,"location":{"index":2,"uri":"file:///test-header-2.h"},"mimeType":"text/plain","roles":["resultFile"]},{"length":28,"location":{"index":3,"uri":"file:///test-header-3.h"},"mimeType":"text/plain","roles":["resultFile"]},{"length":41,"location":{"index":0,"uri":"file:///main.cpp"},"mimeType":"text/plain","roles":["resultFile"]}],"columnKind":"unicodeCodePoints","results":[{"codeFlows":[{"threadFlows":[{"locations":[{"importance":"essential","location":{"message":{"text":"Message #1"},"physicalLocation":{"artifactLocation":{"index":1},"region":{"endColumn":8,"endLine":2,"startColumn":1,"startLine":1}}}},{"importance":"important","location":{"message":{"text":"Message #2"},"physicalLocation":{"artifactLocation":{"index":2},"region":{"endColumn":8,"endLine":2,"startColumn":1,"startLine":1}}}},{"importance":"unimportant","location":{"message":{"text":"Message #3"},"physicalLocation":{"artifactLocation":{"index":3},"region":{"endColumn":8,"endLine":2,"startColumn":1,"startLine":1}}}}]}]}],"locations":[{"physicalLocation":{"artifactLocation":{"index":0},"region":{"endColumn":8,"endLine":2,"startColumn":5,"startLine":2}}}],"message":{"text":"Redefinition of 'foo'"},"ruleId":"clang.unittest","ruleIndex":0}],"tool":{"driver":{"fullName":"sarif test runner","informationUri":"https://clang.llvm.org/docs/UsersManual.html","language":"en-US","name":"sarif test","rules":[{"fullDescription":{"text":"Example rule created during unit tests"},"id":"clang.unittest","name":"clang unit test"}],"version":"1.0.0"}}}],"version":"2.1.0"})";
+      R"({"$schema":"https://docs.oasis-open.org/sarif/sarif/v2.1.0/cos02/schemas/sarif-schema-2.1.0.json","runs":[{"artifacts":[{"length":27,"location":{"index":1,"uri":"file:///test-header-1.h"},"mimeType":"text/plain","roles":["resultFile"]},{"length":30,"location":{"index":2,"uri":"file:///test-header-2.h"},"mimeType":"text/plain","roles":["resultFile"]},{"length":28,"location":{"index":3,"uri":"file:///test-header-3.h"},"mimeType":"text/plain","roles":["resultFile"]},{"length":41,"location":{"index":0,"uri":"file:///main.cpp"},"mimeType":"text/plain","roles":["resultFile"]}],"columnKind":"unicodeCodePoints","results":[{"codeFlows":[{"threadFlows":[{"locations":[{"importance":"essential","location":{"message":{"text":"Message #1"},"physicalLocation":{"artifactLocation":{"index":1},"region":{"endColumn":8,"endLine":2,"startColumn":1,"startLine":1}}}},{"importance":"important","location":{"message":{"text":"Message #2"},"physicalLocation":{"artifactLocation":{"index":2},"region":{"endColumn":8,"endLine":2,"startColumn":1,"startLine":1}}}},{"importance":"unimportant","location":{"message":{"text":"Message #3"},"physicalLocation":{"artifactLocation":{"index":3},"region":{"endColumn":8,"endLine":2,"startColumn":1,"startLine":1}}}}]}]}],"level":"warning","locations":[{"physicalLocation":{"artifactLocation":{"index":0},"region":{"endColumn":8,"endLine":2,"startColumn":5,"startLine":2}}}],"message":{"text":"Redefinition of 'foo'"},"ruleId":"clang.unittest","ruleIndex":0}],"tool":{"driver":{"fullName":"sarif test runner","informationUri":"https://clang.llvm.org/docs/UsersManual.html","language":"en-US","name":"sarif test","rules":[{"fullDescription":{"text":"Example rule created during unit tests"},"id":"clang.unittest","name":"clang unit test"}],"version":"1.0.0"}}}],"version":"2.1.0"})";
 
   const char *SourceText = "int foo = 0;\n"
                            "int foo = 1;\n"
@@ -309,10 +311,12 @@
   // WHEN: A result containing code flows and diagnostic locations is added
   Writer.createRun("sarif test", "sarif test runner", "1.0.0");
   unsigned RuleIdx = Writer.createRule(Rule);
-  const SarifResult &Result = SarifResult::create(RuleIdx)
-                                  .setLocations({DiagLoc})
-                                  .setDiagnosticMessage("Redefinition of 'foo'")
-                                  .setThreadFlows(Threadflows);
+  const SarifResult &Result =
+      SarifResult::create(RuleIdx)
+          .setLocations({DiagLoc})
+          .setDiagnosticMessage("Redefinition of 'foo'")
+          .setThreadFlows(Threadflows)
+          .setDiagnosticLevel(SarifResultLevel::Warning);
   Writer.appendResult(Result);
   std::string Output = serializeSarifDocument(Writer.createDocument());