test-gen

A command that creates Go tests from a file, function, or package, using table-driven test cases for normal inputs, edge cases, and errors.

In plain words
What is it for?
Use it to generate tests for Go code and review the resulting coverage for missing cases.
Why use it?
It helps cover expected behavior and less obvious failures while matching the testing tools already used by the project.

Command

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/gopherguides/gopher-ai/test-gen
Clone the repo
git clone --depth 1 https://github.com/gopherguides/gopher-ai
Per session 8 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,572 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00008 $0.01572
Opus 5 $0.00004 $0.00786
Sonnet 5 $0.00002 $0.00314
Haiku 4.5 $0.00001 $0.00157

Measured 2d ago against content hash c5f96878aaeb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

test-gen scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/go-dev/commands/test-gen.md · 181 lines

How it starts

The opening of the file, as written. The whole thing — 181 lines — stays where its author put it; the contents beside it link to each section on GitHub.

If $ARGUMENTS is empty or not provided:

Usage: /test-gen <target>

  • /test-gen pkg/auth/login.go — generate tests for a file
  • /test-gen HandleAuthentication — generate tests for a function
  • /test-gen pkg/utils/ — generate tests for a package

Workflow: detect testing setup (testify/gomock/etc.) → analyze target → generate test cases (happy path, edge cases, errors) → create test file with table-driven patterns → self-review for coverage gaps.

Ask: "What file or function would you like me to generate tests for?"


If $ARGUMENTS is provided:

Generate comprehensive Go tests for the specified code with table-driven patterns and edge cases.

Loop Initialization

!if [ ! -x "${CLAUDE_PLUGIN_ROOT}/scripts/setup-loop.sh" ]; then echo "ERROR: Plugin cache stale. Run /gopher-ai-refresh (or refresh-plugins.sh) and restart Claude Code."; exit 1; else "${CLAUDE_PLUGIN_ROOT}/scripts/setup-loop.sh" "test-gen" "COMPLETE"; fi

Configuration

  • Target: $ARGUMENTS (file path or function name)

Steps

1. Detect Testing Environment

  • testify: go list -m all | grep testify
  • gomock: go list -m all | grep gomock
  • mockery: look for mockery.yaml / .mockery.yaml
  • Existing _test.go patterns

Also detect: file naming (*_test.go), package organization (same vs _test suffix), assertions (testify assert/require vs stdlib), mocking (gomock, mockery, hand-written).

2. Analyze Target

Read the target and extract: function signatures + parameters, return types and possible values, dependencies/interfaces, error conditions and returns, side effects (mutations, I/O, network), conditional branches and logic paths.

3. Identify Test Cases

Category Examples
Happy path Basic functionality, expected returns, standard use cases
Edge cases Empty inputs (nil/""/[]byte{}/empty slice); boundary values (0, -1, max int, empty string); single vs multiple elements; Unicode/special chars
Error scenarios Invalid input types, out-of-range values, missing required parameters, context cancellation, I/O failures
Concurrency (if applicable) Race conditions, deadlocks, parallel execution with t.Parallel()

Read the full file on GitHub · 181 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 181 lines · 8 tokens per session scan A c5f96878aaeb

Subscribe to this mod's changes

test-gen is a command published in the GitHub repository gopherguides/gopher-ai (21 stars, last pushed 2d ago), licensed MIT. It adds 8 tokens to every session and 1,572 once invoked, about $0.0000 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.