Add regression test for #49 (remove mutator after move)

[erikras-richard-agent]

Adds regression test coverage for issue #49 where the remove mutator would remove the wrong field from the screen after items were reordered with the move mutator.

The bug was fixed in commit f69ab19 (Nov 2020) by using copyField which clears lastFieldState to force React component re-renders.

This test ensures the fix continues to work by:

1. Creating two customers [0, 1]
2. Moving them to [1, 0]
3. Removing index 1 (original item 0)
4. Verifying the correct item was removed and field state is correct

Summary by CodeRabbit

• Tests
  • Added regression test to validate the correct behavior of move and remove operations on array fields in form state.

[coderabbitai]

📝 Walkthrough

Walkthrough

A new regression test file validates the interaction between move and remove operations on arrays in final-form-arrays. The test verifies that array reordering followed by element removal correctly updates both array values and field state entries, including cleanup of all nested field references.

Changes

Cohort / File(s)	Summary
Regression Test for Move/Remove Interaction src/remove.move-bug-49.test.ts	New Jest test that validates correct field state management when move is called on an array followed by remove, ensuring array contents, field entries, and nested field references are properly updated and cleaned.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• Fix #95: Preserve empty array when removing last item #104 — Addresses the remove mutator's handling of array values and field entries preservation.
• Fix #51: Preserve field functions when moving fields with different shapes #105 — Targets move/remove field-state handling logic to ensure correct swapping and removal of field entries.
• Test: Regression test for data preservation after remove (#165) #106 — Adds regression tests for array element shifts and field-state preservation following array mutations.

Suggested reviewers

• erikras

Poem

🐰 A test hops in to check the way,
That move and remove dance and play!
Fields swap and shrink with careful care,
Array entries vanish in thin air. ✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and accurately describes the main change: adding a regression test for issue #49 related to the remove mutator after move operations.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/remove.move-bug-49.test.ts`:
- Around line 61-65: The test currently only checks existence for nested fields
'customers[0].id' and 'customers[0].name' which can hide stale values; update
the assertions for state.fields['customers[0].id'] and
state.fields['customers[0].name'] to assert their .value equals the expected
primitives (e.g., 2 for id and 'Customer `#2`' for name) instead of using
toBeDefined(), keeping the existing check for state.fields['customers[0]'].value
object as-is to ensure both the composite and nested field values are validated.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 331a17d6-ed05-4af0-b3ce-a7b9c05477ce

📥 Commits

Reviewing files that changed from the base of the PR and between ed07005 and 033620a.

📒 Files selected for processing (1)

• src/remove.move-bug-49.test.ts

[coderabbitai]

🧹 Nitpick | 🔵 Trivial

Assert nested surviving field values, not just existence.

At Line 64 and Line 65, toBeDefined() can still pass with stale nested values. Add value assertions to harden the regression test.

Suggested test-strengthening diff

     expect(state.fields['customers[0].id']).toBeDefined()
     expect(state.fields['customers[0].name']).toBeDefined()
+    expect(state.fields['customers[0].id'].value).toBe(2)
+    expect(state.fields['customers[0].name'].value).toBe('Customer `#2`')

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

	// Field state should reflect the remaining customer at index 0
	expect(state.fields['customers[0]']).toBeDefined()
	expect(state.fields['customers[0]'].value).toEqual({ id: 2, name: 'Customer #2' })
	expect(state.fields['customers[0].id']).toBeDefined()
	expect(state.fields['customers[0].name']).toBeDefined()
	// Field state should reflect the remaining customer at index 0
	expect(state.fields['customers[0]']).toBeDefined()
	expect(state.fields['customers[0]'].value).toEqual({ id: 2, name: 'Customer `#2`' })
	expect(state.fields['customers[0].id']).toBeDefined()
	expect(state.fields['customers[0].name']).toBeDefined()
	expect(state.fields['customers[0].id'].value).toBe(2)
	expect(state.fields['customers[0].name'].value).toBe('Customer `#2`')

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@src/remove.move-bug-49.test.ts` around lines 61 - 65, The test currently only
checks existence for nested fields 'customers[0].id' and 'customers[0].name'
which can hide stale values; update the assertions for
state.fields['customers[0].id'] and state.fields['customers[0].name'] to assert
their .value equals the expected primitives (e.g., 2 for id and 'Customer `#2`'
for name) instead of using toBeDefined(), keeping the existing check for
state.fields['customers[0]'].value object as-is to ensure both the composite and
nested field values are validated.