Gomega is a Go library for writing test assertions with matchers, including support for asynchronous checks and several specialized testing sub-libraries. It is used by Go developers, especially alongside the Ginkgo behavior-driven testing framework, to express and evaluate test expectations. The catalogue entries are Claude Code skills and a plugin that help agents use Gomega's matchers and testing idioms.
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.
npx skills add onsi/gomega --skill matchersgit clone --depth 1 https://github.com/onsi/gomegaWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/onsi/gomega/matchers)<a href="https://agentmods.dev/skills/onsi/gomega/matchers"><img src="https://agentmods.dev/badge/skills/onsi/gomega/matchers/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/onsi/gomega/matchers"><img src="https://agentmods.dev/badge/skills/onsi/gomega/matchers.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00163 | $0.02215 |
| Opus 5 | $0.00081 | $0.01107 |
| Sonnet 5 | $0.00033 | $0.00443 |
| Haiku 4.5 | $0.00016 | $0.00221 |
Grade A, and why
matchers 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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Gomega matcher catalog
Full reference: https://onsi.github.io/gomega/#provided-matchers. Assumes dot-import.
Three rules: prefer the most specific matcher — it produces far better failure messages. Every matcher is negatable (NotTo/ShouldNot). Many matchers accept other matchers as arguments (e.g. ContainElement(ContainSubstring("x"))) — compose freely. Anything taking a format string, args ...any runs fmt.Sprintf on it.
Asserting Equivalence
Equal(expected)— deep equality viareflect.DeepEqual; type-strict (actual and expected must be the same type). The default; reach for something more specific first.BeEquivalentTo(expected)— likeEqualbut converts actual's type to expected's first. Laxer and risky —5.1matchesBeEquivalentTo(5)via truncation. Never use with numbers (useBeNumerically); fine for type aliases.BeComparableTo(expected, options ...cmp.Option)— deep equality via go-cmp (github.com/google/go-cmp); passcmp.Optionsto ignore fields, compare unexported, set tolerances, etc.BeIdenticalTo(expected)—==identity; for primitives, or to assert two pointers point to the same memory.BeAssignableToTypeOf(expected)— succeeds if actual is assignable to a variable of expected's type. Asserts type, not value.
Asserting Presence
BeNil()— actual isnil. Gotcha: a non-nil interface holding a nil concrete pointer is notnil.BeZero()— actual is the zero value for its type (ornil).BeEmpty()— actual (string/array/map/chan/slice/iterator) has zero length.
Asserting Truthiness
BeTrue/BeFalse require a bool (no "truthiness" — use ShouldNot(BeNil())/ShouldNot(BeZero()) for presence).
BeTrue()— actual istrue. Weak failure message; preferBeTrueBecause.BeFalse()— actual isfalse. PreferBeFalseBecause.BeTrueBecause(reason, args...)—BeTruewith an explanatory message. Best practice.BeFalseBecause(reason, args...)—BeFalsewith an explanatory message. Best practice.
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.
- 9d ago First seen · 127 lines · 163 tokens per session scan A b35213dc2eb3
matchers is a skill published in the GitHub repository onsi/gomega (2,355 stars, last pushed 12d ago), licensed MIT. It adds 163 tokens to every session and 2,215 once invoked, about $0.0008 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.
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