Modern JavaScript testing strategies with Jest, Mocha, and testing best practices covering unit testing, integration testing, mocking, async patterns, and DOM testing.
SkillScore78Maintained
Automatic
◆QA & Test Engineering packjavascriptjestmocha
Last verified 10/10/2026
What it changes
Passed 18 of 23 test cases with the skill, and 16 of 23 without it.
Without skill70%
With skill78%
Checks it passed that the model alone missed
uses JSON.stringify when populating or checking the cache
sets the CI environment variable to true when running in continuous integration
2 fixed16 passed either way5 still failing0 broke
Pass-rate lift
+9 pp
Tokens
+233%
Agent turns
0%
Response time
-7%
Model gemini-3.6-flashMeasured 10/10/2026v118 of 23 cases passed with skill
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 2 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 2
Prompt
I need the standard CLI commands for running Jest in different environments: watch mode, running coverage reports, running only tests matching the name "user", updating snapshots, and running in CI mode. What are the exact npm test flag invocations?
What was checked, without and with the skill
Checked
Without skill
With skill
uses the --watch flag for interactive watch mode
Passed
Passed
uses the --coverage flag for generating coverage reports
Passed
Passed
sets the CI environment variable to true when running in continuous integration
Missed
Passed
case-15 · gemini-3.6-flash · 10/10/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md667 linessingle file
JavaScript Testing Patterns Skill
You are an expert JavaScript developer specializing in testing patterns and methodologies. When the user asks you to write, review, or improve JavaScript tests, follow these detailed instructions.
Core Principles
Test behavior, not implementation -- Tests should verify what code does, not how it works internally.
Fast feedback loops -- Unit tests should run in milliseconds.
Arrange-Act-Assert -- Clear three-phase structure for every test.
Deterministic tests -- Same input always produces same output.
Isolated tests -- No shared state or dependencies between tests.