1 files changed, 23 insertions, 0 deletions
diff --git a/spec/frontend/__helpers__/graphql_helpers_spec.js b/spec/frontend/__helpers__/graphql_helpers_spec.js
new file mode 100644
index 00000000000..dd23fbbf4e9
--- /dev/null
+++ b/spec/frontend/__helpers__/graphql_helpers_spec.js
@@ -0,0 +1,23 @@
+import { stripTypenames } from './graphql_helpers';
+
+describe('stripTypenames', () => {
+  it.each`
+    input                                                  | expected
+    ${{}}                                                  | ${{}}
+    ${{ __typename: 'Foo' }}                               | ${{}}
+    ${{ bar: 'bar', __typename: 'Foo' }}                   | ${{ bar: 'bar' }}
+    ${{ bar: { __typename: 'Bar' }, __typename: 'Foo' }}   | ${{ bar: {} }}
+    ${{ bar: [{ __typename: 'Bar' }], __typename: 'Foo' }} | ${{ bar: [{}] }}
+    ${[]}                                                  | ${[]}
+    ${[{ __typename: 'Foo' }]}                             | ${[{}]}
+    ${[{ bar: [{ a: 1, __typename: 'Bar' }] }]}            | ${[{ bar: [{ a: 1 }] }]}
+  `('given $input returns $expected, with all __typename keys removed', ({ input, expected }) => {
+    const actual = stripTypenames(input);
+    expect(actual).toEqual(expected);
+    expect(input).not.toBe(actual);
+  });
+
+  it('given null returns null', () => {
+    expect(stripTypenames(null)).toEqual(null);
+  });
+});