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Guidelines for writing robust CLI end-to-end tests using BATS

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SKILL.md

name CLI E2E Testing
description Guidelines for writing robust CLI end-to-end tests using BATS

CLI E2E Testing

Tests use BATS (Bash Automated Testing System) located in e2e/.

Quick Start

# Run all tests
./e2e/run.sh

# Run specific test file
./e2e/test/libs/bats/bin/bats e2e/tests/02-parallel/t03-volumes.bats

Test File Template

#!/usr/bin/env bats

load '../../helpers/setup'

setup() {
    # Use unique names with timestamp to avoid conflicts
    export TEST_DIR="$(mktemp -d)"
    export RESOURCE_NAME="e2e-test-$(date +%s)"
}

teardown() {
    # Always clean up temp directories
    [ -n "$TEST_DIR" ] && [ -d "$TEST_DIR" ] && rm -rf "$TEST_DIR"
}

@test "descriptive test name" {
    run $CLI_COMMAND subcommand args
    assert_success
    assert_output --partial "expected text"
}

Assertions

# Exit status
assert_success                    # exit code 0
assert_failure                    # exit code != 0

# Output matching
assert_output --partial "text"    # output contains text
refute_output --partial "text"    # output does NOT contain text
assert_output --regexp "pattern"  # output matches regex

# Line matching
assert_line --index 0 "first line"

Key Patterns

1. Unique Resource Names

# Always use timestamp to prevent test conflicts
export VOLUME_NAME="e2e-volume-$(date +%s)"
export ARTIFACT_NAME="e2e-artifact-$(date +%s)"

2. Inline Config Files (Important!)

Always create config files inline within tests instead of using shared fixture files. This avoids conflicts when multiple test suites run in parallel (each test suite may compose the same config simultaneously).

@test "vm0 compose with custom config" {
    echo "# Create config inline"
    cat > "$TEST_DIR/vm0.yaml" <<EOF
version: "1.0"

agents:
  $AGENT_NAME:
    provider: claude-code
    description: "Test agent"
EOF

    run $CLI_COMMAND compose "$TEST_DIR/vm0.yaml"
    assert_success
}

Why inline configs:

  • Each test file gets its own isolated $TEST_DIR (created in setup())
  • Parallel test execution won't conflict on shared config files
  • Test is self-contained and easier to understand

3. Debug Output with Echo Comments

@test "multi-step test" {
    echo "# Step 1: Setup..."
    # ... setup code ...

    echo "# Step 2: Execute..."
    run $CLI_COMMAND ...

    echo "# Step 3: Verify..."
    assert_success
}

4. Extract IDs from Output

# Extract UUID patterns
CHECKPOINT_ID=$(echo "$output" | grep -oP 'Checkpoint:\s*\K[a-f0-9-]{36}' | head -1)
SESSION_ID=$(echo "$output" | grep -oP 'Session:\s*\K[a-f0-9-]{36}' | head -1)

# Verify extraction succeeded
[ -n "$CHECKPOINT_ID" ] || {
    echo "# Failed to extract checkpoint ID"
    echo "$output"
    return 1
}

5. Test Both Success and Failure

@test "valid input succeeds" {
    run $CLI_COMMAND volume init
    assert_success
}

@test "invalid input fails with error" {
    run $CLI_COMMAND volume pull "nonexistent"
    assert_failure
    assert_output --partial "not found"
}

6. Suppress Output for Setup Commands

# Use >/dev/null for setup commands that must succeed
$CLI_COMMAND artifact init >/dev/null
$CLI_COMMAND artifact push >/dev/null

# Only use `run` when you need to check output/status
run $CLI_COMMAND artifact push
assert_success

File Organization

e2e/
├── tests/
│   ├── 01-serial/         # Tests that must run sequentially (before parallel tests)
│   │   ├── ser-t01-smoke.bats
│   │   └── ser-t02-vm0-scope.bats
│   └── 02-parallel/       # Feature-specific tests (run in parallel with -j 10)
│       ├── t01-validation.bats
│       ├── t03-volumes.bats
│       └── t04-vm0-artifact-checkpoint.bats
└── helpers/
    └── setup.bash         # Shared setup (loads bats-assert)

Serial vs Parallel Tests

Default: Place tests in 02-parallel/. Tests run in parallel with -j 10.

Use 01-serial/ when:

  • Test modifies shared user state (e.g., scope set --force)
  • Test sets up state that parallel tests depend on
  • Race conditions could occur with parallel execution

Serial test naming: Use ser-tXX-name.bats prefix for files in 01-serial/.

Note: Config files should be created inline within each test (see "Inline Config Files" pattern above), not stored in a shared fixtures directory.

Naming Convention

  • Serial test files: ser-tXX-feature-name.bats (in 01-serial/)
  • Parallel test files: tXX-feature-name.bats (in 02-parallel/)
  • Test resources: e2e-{type}-$(date +%s)

CI Integration

Tests run in two steps:

# Step 1: Run serial tests sequentially (establishes shared state like scope)
bats ./e2e/tests/01-serial/*.bats

# Step 2: Run parallel tests with -j 10
bats -j 10 --no-parallelize-within-files ./e2e/tests/02-parallel/*.bats
  • Serial tests run first to establish stable shared state
  • -j 10: Run up to 10 test files in parallel
  • --no-parallelize-within-files: Tests within a file run sequentially

Checklist

Before submitting:

  • Uses unique resource names with timestamp
  • Creates config files inline (not in shared fixtures)
  • Has setup() and teardown() for cleanup
  • Tests both success and failure cases
  • Includes debug echo comments for multi-step tests
  • Placed in correct directory (01-serial for shared state, 02-parallel for most tests)
  • Runs successfully: ./e2e/run.sh tests/02-parallel/your-test.bats