typescript-eslint · JoshuaKGoldberg · Feb 1, 2025 · Feb 1, 2024 · Feb 2, 2024 · Jan 22, 2025
diff --git a/packages/eslint-plugin/src/rules/switch-exhaustiveness-check.ts b/packages/eslint-plugin/src/rules/switch-exhaustiveness-check.ts
@@ -142,6 +142,16 @@ export default createRule<Options, MessageIds>({
       return;
     }
 
+    function typeToString(type: ts.Type): string {
+      return checker.typeToString(
+        type,
+        undefined,
+        ts.TypeFormatFlags.AllowUniqueESSymbolType |
+          ts.TypeFormatFlags.UseAliasDefinedOutsideCurrentScope |
+          ts.TypeFormatFlags.UseFullyQualifiedType,
+      );
+    }
+
     function getSwitchMetadata(node: TSESTree.SwitchStatement): SwitchMetadata {
       const defaultCase = node.cases.find(
         switchCase => switchCase.test == null,
@@ -230,7 +240,7 @@ export default createRule<Options, MessageIds>({
               .map(missingType =>
                 tsutils.isTypeFlagSet(missingType, ts.TypeFlags.ESSymbolLike)
                   ? `typeof ${missingType.getSymbol()?.escapedName as string}`
-                  : checker.typeToString(missingType),
+                  : typeToString(missingType),
               )
               .join(' | '),
           },
@@ -282,7 +292,7 @@ export default createRule<Options, MessageIds>({
         )
           ? // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
             missingBranchName!
-          : checker.typeToString(missingBranchType);
+          : typeToString(missingBranchType);
 
         if (
           symbolName &&

diff --git a/packages/eslint-plugin/tests/fixtures/switch-exhaustiveness-check.ts b/packages/eslint-plugin/tests/fixtures/switch-exhaustiveness-check.ts
@@ -0,0 +1,6 @@
+export namespace A {
+  export enum B {
+    C,
+    D,
+  }
+}
diff --git a/packages/eslint-plugin/tests/fixtures/tsconfig.json b/packages/eslint-plugin/tests/fixtures/tsconfig.json
@@ -15,6 +15,7 @@
     "mixed-enums-decl.ts",
     "react.tsx",
     "var-declaration.ts",
-    "errors.ts"
+    "errors.ts",
+    "switch-exhaustiveness-check.ts"
   ]
 }
diff --git a/packages/eslint-plugin/tests/rules/switch-exhaustiveness-check.test.ts b/packages/eslint-plugin/tests/rules/switch-exhaustiveness-check.test.ts
@@ -2947,5 +2947,87 @@ switch (literal) {
         },
       ],
     },
+    {
+      code: `
+        export namespace A {
+          export enum B {
+            C,
+            D,
+          }
+        }
+        declare const foo: A.B;
+        switch (foo) {
+          case A.B.C: {
+            break;
+          }
+        }
+      `,
+      errors: [
+        {
+          column: 17,
+          data: {
+            missingBranches: 'A.B.D',
+          },
+          line: 9,
+          messageId: 'switchIsNotExhaustive',
+          suggestions: [
+            {
+              messageId: 'addMissingCases',
+              output: `
+        export namespace A {
+          export enum B {
+            C,
+            D,
+          }
+        }
+        declare const foo: A.B;
+        switch (foo) {
+          case A.B.C: {
+            break;
+          }
+          case A.B.D: { throw new Error('Not implemented yet: A.B.D case') }
+        }
+      `,
+            },
+          ],
+        },
+      ],
+    },
+    {
+      code: `
+        import { A } from './switch-exhaustiveness-check';
+        declare const foo: A.B;
+        switch (foo) {
+          case A.B.C: {
+            break;
+          }
+        }
+      `,
+      errors: [
+        {
+          column: 17,
+          data: {
+            missingBranches: 'A.B.D',
+          },
+          line: 4,
+          messageId: 'switchIsNotExhaustive',
+          suggestions: [
+            {
+              messageId: 'addMissingCases',
+              output: `
+        import { A } from './switch-exhaustiveness-check';
+        declare const foo: A.B;
+        switch (foo) {
+          case A.B.C: {
+            break;
+          }
+          case A.B.D: { throw new Error('Not implemented yet: A.B.D case') }
+        }
+      `,
+            },
+          ],
+        },
+      ],
+    },
   ],
 });