Add Android testing skill for Claude by SaintPatrck · Pull Request #6370 · bitwarden/android

SaintPatrck · 2026-01-15T18:23:32Z

🎟️ Tracking

TBD

📔 Objective

Introduce a new Claude skill named testing-android-code to provide comprehensive guidance and standardized patterns for writing tests within the Bitwarden Android codebase.

The primary objective is to codify best practices and provide Claude with quick access to reference documentation, examples, and common pitfalls, thereby improving test quality, consistency, and development efficiency.

The skill is composed of the following documents:

A main SKILL.md file that serves as a quick-reference guide, outlining key patterns for testing ViewModels, Compose UIs, Repositories, and Services. It also introduces test data builders and utility classes.
A README.md explaining the purpose and contents of the skill.
Detailed reference documents for:
- test-base-classes.md: Explains the usage of BaseViewModelTest, BitwardenComposeTest, and BaseServiceTest.
- flow-testing-patterns.md: Details how to test StateFlow and EventFlow using Turbine, highlighting the critical differences in their testing patterns.
- critical-gotchas.md: Lists common antipatterns and mistakes, such as misusing assertCoroutineThrows with runTest and forgetting to unmock static functions.
Complete, copy-pasteable examples for testing major components:
- viewmodel-test-example.md
- compose-screen-test-example.md
- repository-test-example.md

⏰ Reminders before review

Contributor guidelines followed
All formatters and local linters executed and passed
Written new unit and / or integration tests where applicable
Protected functional changes with optionality (feature flags)
Used internationalization (i18n) for all UI strings
CI builds passed
Communicated to DevOps any deployment requirements
Updated any necessary documentation (Confluence, contributing docs) or informed the documentation team

🦮 Reviewer guidelines

👍 (:+1:) or similar for great changes
📝 (:memo:) or ℹ️ (:information_source:) for notes or general info
❓ (:question:) for questions
🤔 (:thinking:) or 💭 (:thought_balloon:) for more open inquiry that's not quite a confirmed issue and could potentially benefit from discussion
🎨 (:art:) for suggestions / improvements
❌ (:x:) or ⚠️ (:warning:) for more significant problems or concerns needing attention
🌱 (:seedling:) or ♻️ (:recycle:) for future improvements or indications of technical debt
⛏ (:pick:) for minor or nitpick changes

codecov · 2026-01-15T18:26:12Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.07%. Comparing base (b0084d2) to head (5c0f4f4).
⚠️ Report is 20 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6370      +/-   ##
==========================================
+ Coverage   85.77%   86.07%   +0.30%     
==========================================
  Files         775      776       +1     
  Lines       56203    56151      -52     
  Branches     8123     8132       +9     
==========================================
+ Hits        48207    48334     +127     
+ Misses       5172     4984     -188     
- Partials     2824     2833       +9

☔ View full report in Codecov by Sentry.
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github-actions · 2026-01-15T18:29:49Z

Checkmarx One – Scan Summary & Details – 107fff80-9815-43c5-970b-f536dfa33fc4

Great job! No new security vulnerabilities introduced in this pull request

This commit introduces a new Claude skill named `testing-android-code` to provide comprehensive guidance and standardized patterns for writing tests within the Bitwarden Android codebase. The primary objective is to codify best practices and provide developers with quick access to reference documentation, examples, and common pitfalls, thereby improving test quality, consistency, and development efficiency. The skill is composed of the following documents: - A main `SKILL.md` file that serves as a quick-reference guide, outlining key patterns for testing ViewModels, Compose UIs, Repositories, and Services. It also introduces test data builders and utility classes. - A `README.md` explaining the purpose and contents of the skill. - Detailed reference documents for: - `test-base-classes.md`: Explains the usage of `BaseViewModelTest`, `BitwardenComposeTest`, and `BaseServiceTest`. - `flow-testing-patterns.md`: Details how to test StateFlow and EventFlow using Turbine, highlighting the critical differences in their testing patterns. - `critical-gotchas.md`: Lists common antipatterns and mistakes, such as misusing `assertCoroutineThrows` with `runTest` and forgetting to unmock static functions. - Complete, copy-pasteable examples for testing major components: - `viewmodel-test-example.md` - `compose-screen-test-example.md` - `repository-test-example.md`

withinfocus · 2026-01-29T18:08:33Z

https://bitwarden.slack.com/archives/C09MHQNCSKD/p1769693094966979 -- is this a skill or a prompt? And do we think this will move to the marketplace in time or is so specific it will just be here? I am thinking about the reviewer agent benefitting.

SaintPatrck · 2026-01-29T18:52:50Z

@withinfocus it's a Skill, although I'm toying with the idea of making it a Rule once I've had a chance to tinker with them.

I keep going back-and-forth on moving it to the marketplace or keeping it here given it's so specialized. My main hesitation is the friction it may introduce for maintenance. If we consider it a living document to update as we fine-tune Claude for this repo, I would prefer it reside here. I feel like that will encourage and facilitate faster iterations.

The reviewer agent, and the implementor/developer agent being built, will inherently have access to this as long as they're initiated in the repo root. If we move it to the marketplace the plugin has to be manually installed everywhere. There may be ways to configure the repo to automagically install the marketplace+plugin, but I've not looked into that approach thoroughly.

For the sake of getting something started I think it's best we begin with it here, iterate a bit until the team is confident with it, then promote it to the marketplace if there's a larger desire/need to do so.

Edit:
With all of that being said, I just remembered we have at least one other Android repo. If it follows the guidelines and best practices we've established in this repo, that's a good enough reason for me to promote it to the marketplace sooner rather than later.

david-livefront · 2026-01-29T18:55:56Z

.claude/skills/testing-android-code/examples/compose-screen-test-example.md

+    }
+
+    companion object {
+        private val DEFAULT_STATE = ExampleState(


Can we move this out of the companion object and just have it be at the top-level of the file?

david-livefront · 2026-01-29T18:57:03Z

.claude/skills/testing-android-code/examples/viewmodel-test-example.md

+    }
+
+    // Default state for assertions - always define complete expected states
+    private val defaultState = ExampleState(


Stuff like this is usually top-level

..and done.

david-livefront · 2026-01-29T18:57:17Z

.claude/skills/testing-android-code/examples/viewmodel-test-example.md

+    private fun createViewModel(
+        initialState: ExampleState? = null,
+    ): ExampleViewModel = ExampleViewModel(
+        savedStateHandle = SavedStateHandle().apply { set("state", initialState) },


Moves the `DEFAULT_STATE` constant from a class-level property to a top-level private val in both `viewmodel-test-example.md` and `compose-screen-test-example.md`. This change improves consistency and cleans up the test class structure by removing the `companion object` in the Compose test example.

claude · 2026-01-29T19:01:49Z

Claude finished @SaintPatrck's task in 2m 18s —— View job

Code Review Summary

PR: #6370 - Add Android testing skill for Claude

Review Status: Approved

This PR introduces a comprehensive testing skill that codifies Bitwarden Android testing patterns for Claude. The documentation is well-structured and provides accurate guidance.

What was reviewed:

Skill documentation structure and completeness
File path accuracy against actual codebase
Consistency with existing codebase patterns
Previous review feedback resolution

Verification performed:

All referenced file paths verified to exist at specified locations
BaseViewModelTest, BitwardenComposeTest, BaseServiceTest locations confirmed
bufferedMutableSharedFlow, assertCoroutineThrows, Result extensions confirmed
Example patterns align with actual test implementations

Previous feedback addressed:

DEFAULT_STATE moved to top-level in examples (per david-livefront)
assertSuccess patterns removed from repository example
TestHelpers path corrected (per theMickster)
KDoc in examples clarified as Claude context association

No new issues found. The skill documentation accurately reflects codebase conventions and will provide valuable guidance for writing consistent tests.

This review was performed by Claude.

david-livefront · 2026-01-29T22:27:03Z

.claude/skills/testing-android-code/examples/compose-screen-test-example.md

+
+    /**
+     * Test: Back button sends action to ViewModel
+     */


We generally don't have docs on our tests, right?

No, this is so Claude has examples of associating what is being tested to expected test names. Claude is not actually writing KDoc like this.

.claude/skills/testing-android-code/examples/repository-test-example.md

david-livefront · 2026-01-29T22:29:00Z

.claude/skills/testing-android-code/examples/repository-test-example.md

+
+    /**
+     * PATTERN: For error paths that require exceptions, create isolated
+     * repository instances with mocked dependencies.


Do we ever do this?

No. It's coming from #6424. I'm going to remove it since we don't encounter this scenario often.

- Compose tests: Change @beforeeach to @before (JUnit 4) - Compose tests: Add dialog testing examples with isDialog() - Repository tests: Fix Fake pattern to use private storage with setter - Repository tests: Remove fictional emitData() helper method - SKILL.md: Remove PR review references from pattern descriptions Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Rename "Reference Implementations" to "Complete Examples" and update paths to point to the local example files instead of codebase files. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

SaintPatrck · 2026-01-30T16:15:02Z

These latest changes are looking good. #6442 was generated after the latest updates and correctly follows our testing guidelines for View Models. 🥳

theMickster

I think we address the TestHelpers.kt and then we let this thing fly!

theMickster · 2026-02-02T17:10:37Z

.claude/skills/testing-android-code/SKILL.md

+
+**Locations:**
+- `.asSuccess()`, `.asFailure()`: `core/src/main/kotlin/com/bitwarden/core/data/util/ResultExtensions.kt`
+- `assertCoroutineThrows`: `app/src/test/kotlin/com/x8bit/bitwarden/data/util/TestHelpers.kt`


❓I don't see this file in the location mentioned. Did it move recently?

Nice catch! It did. Thank you.

github-actions bot added the t:ci Change Type - Updates to automated workflows label Jan 15, 2026

SaintPatrck force-pushed the claude/testing-android-code-skill branch 3 times, most recently from ebe7698 to f83fdfc Compare January 29, 2026 17:38

SaintPatrck force-pushed the claude/testing-android-code-skill branch from f83fdfc to db99690 Compare January 29, 2026 17:49

SaintPatrck marked this pull request as ready for review January 29, 2026 17:50

SaintPatrck requested a review from a team as a code owner January 29, 2026 17:50

SaintPatrck requested review from a team and david-livefront January 29, 2026 17:51

SaintPatrck added the ai-review Request a Claude code review label Jan 29, 2026

david-livefront reviewed Jan 29, 2026

View reviewed changes

.claude/skills/testing-android-code/examples/repository-test-example.md Outdated Show resolved Hide resolved

david-livefront reviewed Jan 29, 2026

View reviewed changes

SaintPatrck and others added 3 commits January 29, 2026 21:26

Update test base classes reference to point to example files

b14b59a

Rename "Reference Implementations" to "Complete Examples" and update paths to point to the local example files instead of codebase files. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Use assertNull where appropriate

43b52a6

theMickster requested changes Feb 2, 2026

View reviewed changes

Correct TestHelpers path

5c0f4f4

github-actions bot removed the t:ci Change Type - Updates to automated workflows label Feb 2, 2026

github-actions bot added the t:llm Change Type - LLM related change (e.g. CLAUDE.md files) label Feb 2, 2026

SaintPatrck requested a review from theMickster February 2, 2026 17:45

SaintPatrck enabled auto-merge February 2, 2026 18:39

theMickster approved these changes Feb 2, 2026

View reviewed changes

SaintPatrck added this pull request to the merge queue Feb 2, 2026

Merged via the queue into main with commit d49629d Feb 2, 2026
16 checks passed

SaintPatrck deleted the claude/testing-android-code-skill branch February 2, 2026 19:13

Conversation

SaintPatrck commented Jan 15, 2026

🎟️ Tracking

📔 Objective

⏰ Reminders before review

🦮 Reviewer guidelines

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Great job! No new security vulnerabilities introduced in this pull request

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withinfocus commented Jan 29, 2026

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Code Review Summary

Review Status: Approved

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SaintPatrck commented Jan 30, 2026

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