A shared set of RSpec conventions for a Ruby gem’s test suite. It defines how to name test subjects, describe situations, and write expectations so tests read consistently.

Use it when adding or editing RSpec tests, especially tests for models, matchers, analyzers, validators, and attachment behavior.

It makes tests easier to understand and avoids common naming and structure problems. It also helps keep new tests consistent with the existing suite.

spec — Cursor rule by igorkasyanchuk

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 rules/igorkasyanchuk/active_storage_validations/spec

Clone the repo

git clone --depth 1 https://github.com/igorkasyanchuk/active_storage_validations

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.

When invoked 490 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.

Model	Per session	Once invoked
Fable 5	$0.00000	$0.00490
Opus 5	$0.00000	$0.00245
Sonnet 5	$0.00000	$0.00098
Haiku 4.5	$0.00000	$0.00049

Measured 2d ago against content hash 15df2e83342f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

spec 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.

.cursor/rules/spec.mdc · 39 lines

What it actually says

Spec conventions

Boot via rails_helper / .rspec; prefer described_class over repeating the described constant.
Always use a named subject — never anonymous subject { ... } / subject do.
Prefer referencing the name in expectations (expect(metadata)), not bare subject. Shared helpers under spec/**/support/ may call subject (aliases any named subject); RSpec/NamedSubject does not scan helper methods.
Prefer these names (avoid clashing with an existing let of the same name — that causes recursion):

Situation	Name
Fresh model (`Something.new`)	`subject(:model)`
Model after `attach(...)` (body uses `let(:model)`)	`subject(:record)`
Matcher / chained matcher API	`subject(:configured_matcher)`
Analyzer `#metadata` / `#content_type`	`subject(:metadata)` / `subject(:content_type)`
Other return values	descriptive name (`:result`, `:html`, `:valid`, …)

# good
subject(:metadata) { analyzer.metadata }
subject(:record) { model.avatar.attach(file) and model }
subject(:configured_matcher) { matcher.allowing("image/png") }

expect(metadata).to eq({})
expect(record).to be_valid

# bad
subject { analyzer.metadata }
expect(subject).to eq({})

Use describe for named units/topics (#metadata, :less_than, "one", "several", "Edge cases", "working with …") and context for situations (when …, with …, without …, nested and … / which … / that … / but …). Never context "one" — that is a topic, so describe "one".
Prefer let / before for setup; keep it descriptions as outcomes, not conditionals already expressed by the surrounding context.
Domain rules: spec-validators.mdc, spec-matchers.mdc, spec-analyzers.mdc, spec-integration.mdc.

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.

2d ago First seen · 39 lines · 0 tokens per session scan A 15df2e83342f

Subscribe to this mod's changes

spec is a cursor rule published in the GitHub repository igorkasyanchuk/active_storage_validations (1,191 stars, last pushed 10d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 490 tokens. 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.

Backend and APIs Planning Testing active-storage activestorage rails validations

spec

Getting it into your agent

What it costs to keep this loaded

Grade A, and why

Nothing flagged

What it actually says

Spec conventions

What this file has done since we first saw it

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