Claude code init

Author: hadley

.Rbuildignore

@@ -23,3 +23,5 @@
 ^[\.]?air\.toml$
 ^\.vscode$
 ^\.git-blame-ignore-rev$
+^CLAUDE\.md$
+^\.claude$

.claude/settings.local.json

@@ -0,0 +1,8 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(find:*)"
+    ],
+    "deny": []
+  }
+}

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## About This Project
+
+testthat is R's most popular unit testing framework, used by thousands of CRAN packages. It provides functions to make testing R code as fun and addictive as possible, with clear expectations, visual progress indicators, and seamless integration with R package development workflows.
+
+## Key Development Commands
+
+### Testing
+- `devtools::test()` or `Ctrl/Cmd+Shift+T` in RStudio - Run all tests
+- `devtools::test_file("tests/testthat/test-filename.R")` - Run tests in a specific file
+- `testthat::test_local()` - Run tests for local source package
+- `testthat::test_package("testthat")` - Run tests for installed package
+- `R CMD check` - Full package check including tests
+
+### Building and Installation
+- `devtools::load_all()` or `Ctrl/Cmd+Shift+L` - Load package for development
+- `devtools::document()` - Generate documentation
+- `devtools::check()` - Run R CMD check
+- `devtools::install()` - Install package locally
+
+## Core Architecture
+
+### Main Components
+
+1. **Core Testing Functions** (`R/test-that.R`, `R/test-package.R`):
+   - `test_that()` - The fundamental testing function
+   - `test_local()`, `test_package()`, `test_check()` - Different ways to run test suites
+
+2. **Expectations** (`R/expect-*.R`):
+   - Modular expectation functions (equality, conditions, types, etc.)
+   - Each expectation type has its own file following the pattern `expect-[type].R`
+
+3. **Reporters** (`R/reporter*.R`):
+   - Different output formats for test results
+   - Object-oriented design with base `Reporter` class
+   - Includes check, debug, progress, summary, JUnit, TAP formats
+
+4. **Snapshot Testing** (`R/snapshot*.R`):
+   - Value snapshots, file snapshots, output snapshots
+   - Automatic management and comparison of expected outputs
+
+5. **Parallel Testing** (`R/parallel*.R`):
+   - Multi-core test execution
+   - Configuration via `Config/testthat/parallel: true` in DESCRIPTION
+
+6. **Mocking** (`R/mock*.R`, `R/mock2*.R`):
+   - Function mocking capabilities
+   - Both legacy (`mock.R`) and modern (`mock2*.R`) implementations
+
+### Key Design Patterns
+
+- **Editions**: testthat has different "editions" with varying behavior, controlled by `Config/testthat/edition`
+- **Reporters**: Extensible reporting system using R6 classes
+- **Lazy Evaluation**: Expectations use substitute() and lazy evaluation for better error messages
+- **C++ Integration**: Core functionality implemented in C++ for performance
+
+### File Organization
+
+- `R/` - All R source code, organized by functionality
+- `src/` - C++ source code and Makevars
+- `inst/include/testthat/` - C++ headers for other packages to use
+- `tests/testthat/` - Package's own comprehensive test suite
+- `vignettes/` - Documentation on testing concepts and workflows
+
+### Important Configuration
+
+The package uses several DESCRIPTION fields for configuration:
+- `Config/testthat/edition: 3` - Sets testthat edition
+- `Config/testthat/parallel: true` - Enables parallel testing
+- `Config/testthat/start-first` - Tests to run first in parallel mode
+
+### C++ Testing Infrastructure
+
+testthat provides C++ testing capabilities via Catch framework:
+- Headers in `inst/include/testthat/`
+- Test runner infrastructure in `src/test-runner.cpp`
+- Integration with R's testing system
+
+### Snapshot Testing Workflow
+
+- Snapshots stored in `tests/testthat/_snaps/`
+- Different snapshot types: values, files, output
+- Version-specific snapshots for different R versions
+- Use `testthat::snapshot_accept()` to update snapshots
+
+This codebase prioritizes backward compatibility, comprehensive testing, and clear, descriptive error messages to help R developers write better tests.