This happens with the redditService class mock. I'm not sure if the Jest API has changed but the official docs seem to indicate that this code is still functional.
FAIL src/store/topics/tests/actions.spec.js
● store/topics/actions › should fetch topics from server
TypeError: Cannot read property 'mockReturnValueOnce' of undefined
at Object.it (src/store/topics/__tests__/actions.spec.js:16:96)
at process._tickCallback (internal/process/next_tick.js:68:7)
● store/topics/actions › should fetch topics and print to console on error
TypeError: Cannot read property 'mockImplementationOnce' of undefined
at Object.it (src/store/topics/__tests__/actions.spec.js:27:96)
at process._tickCallback (internal/process/next_tick.js:68:7)
FAIL src/store/tests/posts.spec.js
● store/posts integration › should fetch posts and filter
TypeError: Cannot read property 'mockReturnValueOnce' of undefined
at Object.it (src/store/__tests__/posts.spec.js:26:96)
at process._tickCallback (internal/process/next_tick.js:68:7)
● store/posts integration › should select post
TypeError: Cannot read property 'mockReturnValueOnce' of undefined
at Object.it (src/store/__tests__/posts.spec.js:62:97)
at process._tickCallback (internal/process/next_tick.js:68:7)
FAIL src/store/tests/topics.spec.js
● store/topics integration › should fetch topics
TypeError: Cannot read property 'mockReturnValueOnce' of undefined
at Object.it (src/store/__tests__/topics.spec.js:26:96)
at process._tickCallback (internal/process/next_tick.js:68:7)
● store/topics integration › should select topics one by one until valid
TypeError: Cannot read property 'mockReturnValueOnce' of undefined
at Object.it (src/store/__tests__/topics.spec.js:42:96)
at process._tickCallback (internal/process/next_tick.js:68:7)
FAIL src/store/posts/tests/actions.spec.js
● store/posts/actions › should fetch posts when one selected topic
TypeError: Cannot read property 'mockReturnValueOnce' of undefined
at Object.it (src/store/posts/__tests__/actions.spec.js:20:97)
at process._tickCallback (internal/process/next_tick.js:68:7)
● store/posts/actions › should fetch posts from multiple selected topics
TypeError: Cannot read property 'mockReturnValueOnce' of undefined
at Object.it (src/store/posts/__tests__/actions.spec.js:30:97)
at process._tickCallback (internal/process/next_tick.js:68:7)
● store/posts/actions › should fetch posts and print to console on error
TypeError: Cannot read property 'mockReturnValueOnce' of undefined
at Object.it (src/store/posts/__tests__/actions.spec.js:41:97)
at process._tickCallback (internal/process/next_tick.js:68:7)
PASS src/store/posts/tests/selectors.spec.js
PASS src/store/topics/tests/selectors.spec.js
PASS src/store/topics/tests/reducer.spec.js
PASS src/store/posts/tests/reducer.spec.js
PASS src/services/tests/reddit.spec.js
Test Suites: 4 failed, 5 passed, 9 total
Tests: 9 failed, 33 passed, 42 total
Snapshots: 0 total
Time: 0.832s, estimated 1s
Ran all test suites.