feat(testing): add test fixture utilities

[galligan]

Add fixture helpers for test environments:

• createTempDir(): Isolated temp directory with cleanup
• createMockLogger(): In-memory logger for assertions
• createTestConfig(): Config with fixtures directory
• createWorkspace(): Full workspace with temp files
• Comprehensive test coverage

Co-Authored-By: Claude Opus 4.5 noreply@anthropic.com

Contributes to #47

[galligan]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
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• chore(outfitter): sync templates on pack #108
• chore(changesets): ignore app package #107
• fix(errors): avoid TaggedError extends warnings #106
• chore(release): align package versions to 0.1.0 #105
• docs: add README and CHANGELOG for testing, kit, outfitter #95
• feat(templates): add daemon project template #94
• feat(templates): add MCP server project template #93
• feat(templates): add CLI project template #92
• fix(cli): implement confirmDestructive prompts #104
• fix(cli): implement createCLI and command builder #103
• feat(kit): add @outfitter/kit meta-package #91
• docs(daemon): add README and CHANGELOG #90
• fix(daemon): fix locking module bugs (GREEN phase) #89
• test(daemon): add locking module tests (RED phase) #88
• feat(daemon): add errors, platform, and locking module stubs #87
• feat(outfitter): add doctor command for environment validation #86
• feat(outfitter): add init command with project scaffolding #85
• feat(daemon): add IPC communication and health checks #84
• feat(daemon): add types and lifecycle management #83
• feat(index): add FTS5 full-text search implementation #82
• feat(index): add types for FTS5 full-text search #81
• feat(testing): add MCP and CLI test harnesses #80
• feat(testing): add test fixture utilities #79 👈 (View in Graphite)
• feat(mcp): add MCP server implementation with typed handlers #78
• feat(mcp): add types and interfaces for MCP server #77
• feat(ui): add Shape discriminated union and render() #76
• feat(ui): add createTokens semantic color layer #75
• feat(state): add pagination helpers #74
• feat(logging): add DEFAULT_PATTERNS for common secret redaction #73
• feat(ui): add formatRelative() for human-readable timestamps #72
• feat(state): add encodeCursor/decodeCursor for pagination #71
• feat(types): add hashId() for deterministic short identifiers #70
• feat(contracts): add Logger.child() and fix AssertionError category #69
• feat(config): centralize environment variable access with Zod validation #42
• fix(logging): enable redaction by default when global rules exist #41
• docs(ui): add README, CHANGELOG, and TSDoc comments #39
• docs(state): add README, CHANGELOG, and TSDoc comments #38
• docs(file-ops): add README, CHANGELOG, and TSDoc comments #37
• docs(logging): add README, CHANGELOG, and TSDoc comments #36
• docs(config): add README, CHANGELOG, and TSDoc comments #35
• fix(cli): enforce cursor TTL #114
• fix(tests): remove placeholder tests #113
• chore(gitattributes): prefer ours for bun lockfiles #115
• main

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[greptile-apps]

Greptile Summary

• Adds new @outfitter/testing package with fixture utilities for isolated test environments including temp directory management, mock loggers, and file loading
• Implements comprehensive TypeScript configuration and package.json with modular exports for fixtures, CLI harness, and MCP harness modules
• Provides deep object cloning/merging utilities with proper cleanup handling and environment variable isolation for test scenarios

Important Files Changed

Filename	Overview
packages/testing/src/fixtures.ts	New file providing core testing utilities; includes temp directory management, environment isolation, and fixture loading with automatic cleanup
packages/testing/package.json	New package configuration with comprehensive exports structure for testing harnesses; requires review of export paths alignment with actual implementation

Confidence score: 4/5

• This PR is safe to merge with minor concerns about export path alignment
• Score reflects solid implementation patterns but potential mismatch between declared exports and current file structure - package.json declares exports for cli-harness and mcp-harness modules that don't exist yet
• Pay close attention to packages/testing/package.json exports configuration to ensure all declared paths will be implemented

Sequence Diagram

sequenceDiagram
    participant User
    participant FixtureFactory as "Fixture Factory"
    participant TempDir as "Temp Directory"
    participant EnvManager as "Environment Manager"
    participant FileSystem as "File System"

    User->>FixtureFactory: "createFixture(defaults)"
    FixtureFactory->>FixtureFactory: "deepClone(defaults)"
    FixtureFactory-->>User: "factory function"

    User->>FixtureFactory: "factory(overrides)"
    FixtureFactory->>FixtureFactory: "deepMerge(cloned, overrides)"
    FixtureFactory-->>User: "merged fixture"

    User->>TempDir: "withTempDir(fn)"
    TempDir->>FileSystem: "mkdir(tempPath)"
    FileSystem-->>TempDir: "directory created"
    TempDir->>User: "fn(tempPath)"
    User-->>TempDir: "result"
    TempDir->>FileSystem: "rm(tempPath, recursive)"
    TempDir-->>User: "result"

    User->>EnvManager: "withEnv(vars, fn)"
    EnvManager->>EnvManager: "store original env"
    EnvManager->>EnvManager: "set new env vars"
    EnvManager->>User: "fn()"
    User-->>EnvManager: "result"
    EnvManager->>EnvManager: "restore original env"
    EnvManager-->>User: "result"

    User->>FileSystem: "loadFixture(name)"
    FileSystem->>FileSystem: "readFileSync(filePath)"
    FileSystem->>FileSystem: "parse if JSON"
    FileSystem-->>User: "fixture data"

Loading

[galligan]

Reviewed Greptile note: package exports now only include the fixtures entrypoint and the root index re-exports fixtures, so exports align with the current file set in this PR.

[galligan]

Fixed @outfitter/testing exports so the root entrypoint exists at this layer, and added fixtures tests to satisfy package test runs. Restacked and submitted the update with gt.

[galligan]

Restacked after downstack update (formatRelative test stabilization); no additional changes in this PR.

[galligan]

Confirmed @outfitter/testing now ships src/index.ts (root export) and only exports ./fixtures; missing harness subpaths are no longer advertised. Resubmitted after restack.