diff --git a/packages/pyright-internal/src/tests/testUtils.test.ts b/packages/pyright-internal/src/tests/testUtils.test.ts
new file mode 100644
index 0000000000..a5597037ee
--- /dev/null
+++ b/packages/pyright-internal/src/tests/testUtils.test.ts
@@ -0,0 +1,81 @@
+import { AssertionError } from 'assert';
+import { Diagnostic } from '../common/diagnostic';
+import { Uri } from '../common/uri/uri';
+import { FileAnalysisResult, ExpectedResults, validateResultsButBased } from './testUtils';
+import { DiagnosticRule } from '../common/diagnosticRules';
+
+const fakeUri = {} as Uri;
+const fakeDiagnostic = (line: number, code?: DiagnosticRule) =>
+    ({ getRule: () => code, range: { start: { line } } } as Diagnostic);
+
+test('validateResults pass 😀', () => {
+    const expectedResults: ExpectedResults = {
+        errors: [{ line: 1 }, { line: 2 }],
+    };
+    const actualResults: FileAnalysisResult[] = [
+        {
+            errors: [fakeDiagnostic(1), fakeDiagnostic(2)],
+            fileUri: fakeUri,
+            warnings: [],
+            infos: [],
+            unusedCodes: [],
+            deprecateds: [],
+            unreachableCodes: [],
+        },
+    ];
+    validateResultsButBased(actualResults, expectedResults);
+});
+
+test('validateResults wrong number of errors', () => {
+    const expectedResults: ExpectedResults = {
+        errors: [{ line: 1 }, { line: 2 }],
+    };
+    const actualResults: FileAnalysisResult[] = [
+        {
+            errors: [fakeDiagnostic(1)],
+            fileUri: fakeUri,
+            warnings: [],
+            infos: [],
+            unusedCodes: [],
+            deprecateds: [],
+            unreachableCodes: [],
+        },
+    ];
+    expect(() => validateResultsButBased(actualResults, expectedResults)).toThrow(AssertionError);
+});
+
+test('validateResults wrong line number', () => {
+    const expectedResults: ExpectedResults = {
+        errors: [{ line: 2 }],
+    };
+    const actualResults: FileAnalysisResult[] = [
+        {
+            errors: [fakeDiagnostic(1)],
+            fileUri: fakeUri,
+            warnings: [],
+            infos: [],
+            unusedCodes: [],
+            deprecateds: [],
+            unreachableCodes: [],
+        },
+    ];
+    expect(() => validateResultsButBased(actualResults, expectedResults)).toThrow(AssertionError);
+});
+
+test('validateResults wrong code', () => {
+    const expectedResults: ExpectedResults = {
+        errors: [{ line: 1, code: DiagnosticRule.reportUnboundVariable }],
+    };
+    const actualResults: FileAnalysisResult[] = [
+        {
+            errors: [fakeDiagnostic(1, DiagnosticRule.analyzeUnannotatedFunctions)],
+            fileUri: fakeUri,
+            warnings: [],
+            infos: [],
+            unusedCodes: [],
+            deprecateds: [],
+            unreachableCodes: [],
+        },
+    ];
+    expect(() => validateResultsButBased(actualResults, expectedResults)).toThrow(AssertionError);
+});