adding comment when unsupported case found

Author: alexreardon

community/memoize-one/src/5.0.0/transform.spec.ts

@@ -125,7 +125,7 @@ describe('memoize-one@5.0.0 transform', () => {
     );
   });
 
-  it('should wrap identifiers', () => {
+  it('should wrap function identifiers', () => {
     const result = applyTransform(
       transformer,
       format(`
@@ -161,4 +161,34 @@ describe('memoize-one@5.0.0 transform', () => {
       `),
     );
   });
+
+  it('should add a comment when an unsupported equality fn is encountered', () => {
+    const result = applyTransform(
+      transformer,
+      format(`
+        import memoize from 'memoize-one';
+
+        function add(a: number, b: number) {
+          return a + b;
+        }
+
+        const memoized = memoize(add, {});
+      `),
+      { parser: 'tsx' },
+    );
+
+    expect(result).toEqual(
+      format(`
+        /* TODO: (@codeshift) Unable to migrate memoize-one custom equality function.
+Expected a function or an identifier */
+        import memoize from 'memoize-one';
+
+        function add(a: number, b: number) {
+          return a + b;
+        }
+
+        const memoized = memoize(add, {});
+      `),
+    );
+  });
 });

community/memoize-one/src/5.0.0/transform.ts

@@ -1,6 +1,7 @@
 import {
   hasImportDeclaration,
   getDefaultImportSpecifierName,
+  insertCommentToStartOfFile,
 } from '@codeshift/utils';
 import { API, FileInfo, Options } from 'jscodeshift';
 
@@ -26,7 +27,6 @@ export default function transformer(
         call.value.callee.type === 'Identifier' &&
         call.value.callee.name === importName,
     )
-    // .filter(call => call.value.arguments.length === 2)
     .forEach(call => {
       const equalityFn = call.value.arguments[1];
       // we don't need to do anything for calls without an equality fn
@@ -92,6 +92,12 @@ export default function transformer(
         call.value.arguments[1] = customEqualityFn;
         return;
       }
+
+      insertCommentToStartOfFile(
+        j,
+        source,
+        'Unable to migrate memoize-one custom equality function.\nExpected a function or an identifier',
+      );
     });
 
   return source.toSource(options.printOptions);