Agent skill

Mocktail

A skill your agent uses when creating mocks, stubbing methods, verifying interactions, registering fallback values, or choosing between mocks, fakes, and real objects (Mocktail).

MITAuto-check passedMobile

Install Mocktail

skills CLI

$ npx skills add evanca/flutter-ai-rules --skill mocktail -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install evanca/flutter-ai-rules mocktail --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/evanca/flutter-ai-rules.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/mocktail .claude/skills/mocktail && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "mocktail" agent skill from https://github.com/evanca/flutter-ai-rules/tree/main/skills/mocktail into .claude/skills/mocktail/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mocktail", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/evanca/flutter-ai-rules/tree/main/skills/mocktail

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add evanca/flutter-ai-rules --skill mocktail -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install evanca/flutter-ai-rules mocktail --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/evanca/flutter-ai-rules.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/mocktail .agents/skills/mocktail && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "mocktail" agent skill from https://github.com/evanca/flutter-ai-rules/tree/main/skills/mocktail into .agents/skills/mocktail/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mocktail", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add evanca/flutter-ai-rules --skill mocktail -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install evanca/flutter-ai-rules mocktail --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/evanca/flutter-ai-rules.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/mocktail .cursor/skills/mocktail && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "mocktail" agent skill from https://github.com/evanca/flutter-ai-rules/tree/main/skills/mocktail into .cursor/skills/mocktail/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mocktail", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/evanca/flutter-ai-rules.git --path skills/mocktail

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add evanca/flutter-ai-rules --skill mocktail -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install evanca/flutter-ai-rules mocktail --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/evanca/flutter-ai-rules.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/mocktail .gemini/skills/mocktail && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "mocktail" agent skill from https://github.com/evanca/flutter-ai-rules/tree/main/skills/mocktail into .gemini/skills/mocktail/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mocktail", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install evanca/flutter-ai-rules mocktail

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add evanca/flutter-ai-rules --skill mocktail -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/evanca/flutter-ai-rules.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/mocktail .github/skills/mocktail && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "mocktail" agent skill from https://github.com/evanca/flutter-ai-rules/tree/main/skills/mocktail into .github/skills/mocktail/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mocktail", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add evanca/flutter-ai-rules --skill mocktail -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install evanca/flutter-ai-rules mocktail --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/evanca/flutter-ai-rules.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/mocktail .opencode/skills/mocktail && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "mocktail" agent skill from https://github.com/evanca/flutter-ai-rules/tree/main/skills/mocktail into .opencode/skills/mocktail/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "mocktail", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: mocktail
GitHub stars: 649
Token cost: ~828 tokens
SKILL.md length: 269 words
Files: 1
Skills in repo: 37
Repo updated: Sep 14, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

A skill your agent uses when creating mocks, stubbing methods, verifying interactions, registering fallback values, or choosing between mocks, fakes, and real objects (Mocktail).

Works in 7 steps: Mock vs. Fake vs. Real Object → Creating Mocks → Registering Fallback Values → …
Stubbing methods
SKILL.md covers 1. Mock vs. Fake vs. Real Object, 2. Creating Mocks, 3. Registering Fallback Values and 4. Stubbing, plus 4 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Mocktail is an agent skill from evanca/flutter-ai-rules. Use when creating mocks, stubbing methods, verifying interactions, registering fallback values, or choosing between mocks, fakes, and real objects (Mocktail).

Its SKILL.md is about 830 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Mobile. The repository describes itself as: Flutter AI Skills and Rules for Claude, Codex, Cursor, and Other AI-Powered IDEs. The licence is MIT.

When your agent uses it

Stubbing methods
Verifying interactions
Registering fallback values
Choosing between mocks

Example prompts

“/mocktail”

Workflow steps

7 steps, taken from the step headings in SKILL.md.

Mock vs. Fake vs. Real Object
Creating Mocks
Registering Fallback Values
Stubbing
Named Parameters
Verification
Argument Matchers

What it can do on your machine

Read from SKILL.md and the folder at commit 7b9cce2. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are dart).
From the folder's file list and the shell code blocks in SKILL.md.
Network
Links to these hosts (documentation or services it may open):
- github.com
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Mocktail loads about 828 tokens when it runs. Until then it costs about 42 tokens; SKILL.md has 269 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~42
When it runs · the whole SKILL.md, loaded when a task matches: ~828

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from evanca/flutter-ai-rules at commit 7b9cce2, republished under its MIT licence (© evanca). 269 words, ~828 tokens.

Download SKILL.mdSave it as .claude/skills/mocktail/SKILL.md (or your agent's skills folder).

name: mocktail
description: Use when creating mocks, stubbing methods, verifying interactions, registering fallback values, or choosing between mocks, fakes, and real objects (Mocktail).
license: MIT

Mocktail Skill

This skill defines how to correctly use the mocktail package for mocking in Dart and Flutter tests.

1. Mock vs. Fake vs. Real Object

Use	When
Real object	Prefer over mocks when practical.
Fake (`extends Fake`)	Lightweight custom implementation; override only the methods you need. Prefer over mocks when you don't need interaction verification.
Mock (`extends Mock`)	Only when you need to verify interactions (call counts, arguments) or stub dynamic responses.

Never add @override methods or implementations to a class extending Mock.
Only use mocks if your test has verify assertions; otherwise prefer real or fake objects.

2. Creating Mocks

dart

class MockMyService extends Mock implements MyService {}
class FakeMyEvent extends Fake implements MyEvent {}

No code generation required — unlike Mockito, Mocktail uses noSuchMethod at runtime.

3. Registering Fallback Values

Register fallback values before using custom types with argument matchers. Do this in setUpAll or at the top of your test:

dart

setUpAll(() {
  registerFallbackValue(FakeMyEvent());
});

Required for non-nullable custom types used with any(), captureAny(), or captureThat().
Register fallback values for any custom type used with argument matchers.

4. Stubbing

dart

final mock = MockMyService();

// Return a value
when(() => mock.fetchData()).thenReturn('result');

// Throw an error
when(() => mock.fetchData()).thenThrow(Exception('error'));

// Dynamic/async response
when(() => mock.fetchData()).thenAnswer((_) async => 'result');

// Future<void>
when(() => mock.doWork()).thenAnswer((_) async {});

Always stub async methods (returning Future or Future<void>) with thenAnswer.
Stub every method you expect to be called, even if it's not the focus of your test.

5. Named Parameters

Always include all named parameters in both when and verify calls. Use any(named: 'paramName') for those you don't care about:

dart

when(() => mock.fetch(
  id: any(named: 'id'),
  headers: any(named: 'headers'),
)).thenReturn(response);

If a method has default values for named parameters, Mocktail still expects them all to be matched.

6. Verification

dart

verify(() => mock.fetchData());             // called at least once
verifyNever(() => mock.fetchData());        // never called
verify(() => mock.fetchData()).called(2);   // called exactly twice

7. Argument Matchers

dart

// Any positional argument
when(() => mock.process(any())).thenReturn(true);

// Capture arguments for later assertions
final captured = verify(() => mock.process(captureAny())).captured;
print(captured.last);

Use any() for positional parameters when you don't care about the exact value.
Use captureThat() for conditional capturing.
When matching string output, be aware of what .toString() returns for the type.

References

Mocktail GitHub Repository

Files

Just SKILL.md in skills/mocktail of evanca/flutter-ai-rules.

Open the folder on GitHubat commit 7b9cce2

Compare with similar skills

Mocktail next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Mocktail compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Mocktail this skillevanca/flutter-ai-rules	649	—	~828	Automated safety check: Pass	MIT	24 days ago
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Swiftui Protwostraws/SwiftUI-Agent-Skill	5.1k	2 repos	~1.5k	Automated safety check: Pass	MIT	yesterday
Kortix Brandkortix-ai/suna	20k	—	~4k	Automated safety check: Pass	Custom licence	today
Ip As LogoKartikLabhshetwar/better-shot	2.4k	1 repos	~4.3k	Automated safety check: Pass	MIT	7 days ago
Compose Multiplatform Patternsmonta-app/ocpp-emulator	180	5 repos	~2k	Automated safety check: Pass	Apache-2.0	7 days ago

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Architecture Feature First
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Questions about Mocktail

What does Mocktail do?

A skill your agent uses when creating mocks, stubbing methods, verifying interactions, registering fallback values, or choosing between mocks, fakes, and real objects (Mocktail). Mocktail is an agent skill from evanca/flutter-ai-rules. Use when creating mocks, stubbing methods, verifying interactions, registering fallback values, or choosing between mocks, fakes, and real objects (Mocktail).

When should I use Mocktail?

Mocktail fits situations like: stubbing methods; verifying interactions; registering fallback values; choosing between mocks.

How do I install Mocktail in Claude Code?

Run `npx skills add evanca/flutter-ai-rules --skill mocktail -a claude-code`. Or copy the skill folder (skills/mocktail in evanca/flutter-ai-rules) into .claude/skills/mocktail in your project. Claude Code loads it when a task matches its description.

How do I install Mocktail in Codex?

Run `npx skills add evanca/flutter-ai-rules --skill mocktail -a codex`. Or copy the skill folder (skills/mocktail in evanca/flutter-ai-rules) into .agents/skills/mocktail in your project. Codex loads it when a task matches its description.

Can I use Mocktail in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add evanca/flutter-ai-rules --skill mocktail -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/mocktail, .gemini/skills/mocktail, .github/skills/mocktail and .opencode/skills/mocktail in your project.

What does Mocktail need to run?

SKILL.md names no scripts, command-line tools or credentials: Mocktail is instructions for the agent only.

Does Mocktail access the network?

SKILL.md names 1 domain. As links in the text: github.com. This is read from the text; nothing was executed.

Is Mocktail safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Mocktail use?

Mocktail is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Mocktail use?

About 828 tokens (SKILL.md is roughly 3.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Mocktail?

Skills that share tags, products or a category with Mocktail: React Native Best Practices (vercel-labs/openreview, 1.7k stars), Swiftui Pro (twostraws/SwiftUI-Agent-Skill, 5.1k stars), Kortix Brand (kortix-ai/suna, 20k stars) and Ip As Logo (KartikLabhshetwar/better-shot, 2.4k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Mocktail?

evanca (a GitHub user) maintains it in evanca/flutter-ai-rules, which has 649 GitHub stars. The repository holds 37 skills in this directory. The repository was last updated on September 14, 2026.

Source: evanca/flutter-ai-rules on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Mocktail

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Mocktail Skill

1. Mock vs. Fake vs. Real Object

2. Creating Mocks

3. Registering Fallback Values

4. Stubbing

5. Named Parameters

6. Verification

7. Argument Matchers

References

Files

Compare with similar skills

Similar skills

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Related

Questions about Mocktail