Test-driven development. Use when the user wants to build features or fix bugs test-first, mentions "red-green-refactor", or wants integration tests.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# Test-Driven Development
TDD is the red → green loop. This skill is the reference that makes that loop produce tests worth keeping: what a good test is, where tests go, the anti-patterns, and the rules of the loop. Every section applies on every cycle: consult them before and during the loop, not after.
When exploring the codebase, read `GLOSSARY.md` (if it exists) so test names and interface vocabulary match the project's domain language, and respect ADRs in the area you're touching.
## What a good test is
Tests verify behavior through public interfaces, not implementation details. Code can change entirely; tests shouldn't. A good test reads like a specification: "user can checkout with valid cart" tells you exactly what capability exists, and it survives refactors because it doesn't care about internal structure.
See [tests.md](tests.md) for examples and [mocking.md](mocking.md) for mocking guidelines.
## Seams: where tests go
A **seam** is the public boundary you test at: the interface where you observe behavior without reaching inside. Tests live at seams, never against internals.
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Source
GitHub
shaderera/shaderera · 7 stars · license MIT · pushed 2026-10-31 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_tefjdtjxzg44xlpy
GET https://markdownregistry.com/api/v1/resolve?ref=shaderera/shaderera/tdd
GET https://markdownregistry.com/api/v1/blob/92dcbe945ad00a4b9f27de32a40c4e36f9f32984c1824bd528193c02421053b7
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shaderera/shaderera · .claude/skills/code-review/SKILL.md · Review the changes since a fixed point (commit, branch, tag, or merge-base) along two axes: Standards (does the code…
shaderera/shaderera · .claude/skills/codebase-design/SKILL.md · Shared vocabulary for designing deep modules. Use when the user wants to design or improve a module's interface, find…
shaderera/shaderera · .claude/skills/diagnosing-bugs/SKILL.md · Diagnosis loop for hard bugs and performance regressions. Use when the user says "diagnose"/"debug this", or reports…
shaderera/shaderera · .claude/skills/domain-modeling/SKILL.md · Build and sharpen a project's domain model. Use when discussing codebase terminology, writing or editing a GLOSSARY.md…
shaderera/shaderera · .claude/skills/grill-with-docs/SKILL.md · A relentless interview to sharpen a plan or design, which also creates docs (ADR's and glossary) as we go.
shaderera/shaderera · .claude/skills/grilling/SKILL.md · Grill the user relentlessly about a plan, decision, or idea. Use when the user wants to stress-test their thinking, or…
shaderera/shaderera · .claude/skills/improve-codebase-architecture/SKILL.md · Scan a codebase for deepening opportunities, present them as a visual HTML report, then grill through whichever one you…
cursor/plugins · pstack/skills/tdd/SKILL.md · Use only when the user explicitly asks for TDD, a failing test, or a regression test, OR when the bug has an obvious…
cursor/plugins · harness/pstack/claude-code/skills/tdd/SKILL.md · Use only when the user explicitly asks for TDD, a failing test, or a regression test, OR when the bug has an obvious…
nightly-labs/openbot · marketplace/production-catalog/bundles/pstack/skills/tdd/SKILL.md · Use only when the user explicitly asks for TDD, a failing test, or a regression test, OR when the bug has an obvious…
michael-denyer/pstack-claude · plugins/pstack/skills/tdd/SKILL.md · Use only when the user explicitly asks for TDD, a failing test, or a regression test, OR when the bug has an obvious…
