freezeray generate

Generate FreezeRay artifacts (fixtures, schema tests, or migration tests) with granular control over the workflow.

Synopsis

freezeray generate <SUBCOMMAND> [OPTIONS]

# Short alias
freezeray g <SUBCOMMAND> [OPTIONS]

Description

The generate command provides granular operations for creating FreezeRay artifacts separately. Most important: Use generate migration-tests when starting work on a new schema version. This lets you write and test migrations as you develop. The other subcommands (fixtures, schema-tests) are rarely needed because freeze handles them automatically.

Subcommands

`migration-tests` - Generate migration tests ⭐

freezeray generate migration-tests --from-schema <VERSION> --to-schema <VERSION>

Generates a migration test file that validates data migration between two schema versions. This is the primary use case for the generate command. See detailed documentation →

`fixtures` - Generate frozen fixtures (Advanced)

freezeray generate fixtures --schema <VERSION>

Generates frozen SwiftData fixtures for a specific schema version. Rarely needed: freeze does this automatically. See detailed documentation →

`schema-tests` - Generate drift tests (Advanced)

freezeray generate schema-tests --schema <VERSION>

Generates a drift test file that validates a frozen schema hasn’t changed. Rarely needed: freeze does this automatically. See detailed documentation →

Why Use `generate migration-tests`?

The Correct Workflow

Migration tests should be created when you start working on a new schema version, not after:

# 1. Freeze V2
freezeray freeze 2.0.0

# 2. Generate migration test WHEN STARTING V3 work
freezeray generate migration-tests --from-schema 2.0.0 --to-schema 3.0.0

# 3. Edit the generated test, add custom assertions
# 4. Implement V3 schema + migration
# 5. Iterate: run test → fix migration → run test (⌘U)
# 6. When ready, freeze V3
freezeray freeze 3.0.0

This lets you develop with the migration test as you build the new schema.

Key insight: freeze does NOT generate migration tests. You must explicitly run generate migration-tests when starting work on a new schema version.

generate fixtures

Generate frozen fixtures for a specific schema version.

Synopsis

freezeray generate fixtures --schema <VERSION> [OPTIONS]

Description

Generates frozen SwiftData fixtures by:

Discovering the @FreezeSchema(version: "X.Y.Z") annotation
Running a freeze test in iOS Simulator
Extracting fixtures from /tmp to FreezeRay/Fixtures/<VERSION>/

Arguments

`--schema <VERSION>`, `-s <VERSION>`

Required. The schema version to freeze (e.g., “1.0.0”). Must match a @FreezeSchema annotation in your source code:

@FreezeSchema(version: "3.0.0")
enum AppSchemaV3: VersionedSchema {
    // ...
}

Options

`--simulator <NAME>`

Default: iPhone 17 iOS Simulator to use for freezing:

freezeray generate fixtures --schema 3.0.0 --simulator "iPhone 15 Pro"

`--scheme <NAME>`

Default: Auto-detected Xcode scheme to build:

freezeray generate fixtures --schema 3.0.0 --scheme MyApp

`--force`

Overwrite existing fixtures (dangerous!):

freezeray generate fixtures --schema 3.0.0 --force

Only use --force during development before shipping to production. Overwriting frozen fixtures breaks immutability.

`--output <PATH>`

Default: FreezeRay/Fixtures Custom output directory:

freezeray generate fixtures --schema 3.0.0 --output /custom/path

`--config <PATH>`

Path to FreezeRay.yaml config file (experimental):

freezeray generate fixtures --schema 3.0.0 --config .freezeray.yml

What Gets Created

FreezeRay/Fixtures/3.0.0/
├── App-3.0.0.sqlite          # Frozen SQLite database
├── App-3.0.0.sqlite-shm      # SQLite shared memory file
├── schema-3.0.0.sql          # SQL DDL statements
├── schema-3.0.0.json         # Human-readable schema metadata
├── schema-3.0.0.sha256       # SHA256 checksum for drift detection
└── export_metadata.txt       # Timestamp and version info

Examples

Basic usage

freezeray generate fixtures --schema 3.0.0

Output:

🔍 Generating fixtures for schema version 3.0.0...
📱 Running freeze test in simulator (iPhone 17)...
📦 Extracting fixtures from simulator...
✅ Generated fixtures: FreezeRay/Fixtures/3.0.0/
   - App-3.0.0.sqlite
   - schema-3.0.0.sql
   - schema-3.0.0.json
   - schema-3.0.0.sha256
   - export_metadata.txt
   - App-3.0.0.sqlite-shm

Short form

freezeray g fixtures -s 3.0.0

Custom simulator

freezeray generate fixtures --schema 3.0.0 --simulator "iPhone 15"

Common Errors

”No @FreezeSchema found for version X.Y.Z”

Cause: The version doesn’t match any @FreezeSchema annotation. Fix: Add the annotation to your schema:

@FreezeSchema(version: "3.0.0")
enum AppSchemaV3: VersionedSchema {
    // ...
}

“Fixtures already exist”

Cause: Fixtures for this version already exist. Solutions: During development (before shipping):

freezeray generate fixtures --schema 3.0.0 --force

After shipping to production:

# Create new version instead
freezeray generate fixtures --schema 3.0.1

generate schema-tests

Generate drift test for a frozen schema version.

Synopsis

freezeray generate schema-tests --schema <VERSION> [OPTIONS]

Description

Generates a drift test file that validates the current schema definition matches the frozen fixtures. Requirements:

Fixtures must already exist for the specified version
Run freezeray generate fixtures first if needed

Arguments

`--schema <VERSION>`, `-s <VERSION>`

Required. The schema version to generate tests for (e.g., “3.0.0”).

Options

`--force`

Overwrite existing test file:

freezeray generate schema-tests --schema 3.0.0 --force

By default, existing test files are never overwritten (they’re user-owned).

`--config <PATH>`

Path to config file (experimental):

freezeray generate schema-tests --schema 3.0.0 --config .freezeray.yml

What Gets Created

// FreezeRay/Tests/AppSchemaV3_DriftTests.swift
import Testing
import FreezeRay
@testable import MyApp

/// Drift test for AppSchemaV3 v3.0.0
///
/// This test verifies that the current schema definition matches the frozen fixture.
/// If this test fails, it means the schema has been modified since it was frozen.
///
/// Note: Tests run serially to avoid SwiftData store conflicts
@Suite(.serialized)
struct AppSchemaV3_3_0_0_DriftTests {
    @Test("AppSchemaV3 v3.0.0 has not drifted")
    func testAppSchemaV3_3_0_0_Drift() throws {
        // Call the macro-generated check function
        try AppSchemaV3.__freezeray_check_3_0_0()

        // TODO: Add custom data validation here
        // Example:
        // - Verify specific model properties exist
        // - Check relationship configurations
        // - Validate index definitions
    }
}

Generated tests use @Suite(.serialized) to prevent parallel execution issues with SwiftData stores.

Examples

Basic usage

freezeray generate schema-tests --schema 3.0.0

Output:

🔍 Generating schema tests for version 3.0.0...
✅ Generated drift test: AppSchemaV3_DriftTests.swift

Short form

freezeray g schema-tests -s 3.0.0

Regenerate (overwrite)

freezeray generate schema-tests --schema 3.0.0 --force

Common Errors

”No fixtures found for version X.Y.Z”

Cause: Fixtures don’t exist for the specified version. Fix: Generate fixtures first:

freezeray generate fixtures --schema 3.0.0
freezeray generate schema-tests --schema 3.0.0

“Test file already exists”

Cause: The drift test file was already generated. Solutions: If you want to keep your custom assertions:

# Do nothing - the existing test is yours to maintain

If you want to regenerate:

freezeray generate schema-tests --schema 3.0.0 --force

generate migration-tests

Generate migration test from one schema version to another.

Synopsis

freezeray generate migration-tests --from-schema <VERSION> --to-schema <VERSION> [OPTIONS]

Description

Generates a migration test file that validates data migration between two schema versions. This is the key innovation of the generate command: you can create the migration test early in your development workflow, not after the fact. Requirements:

Fixtures must exist for --from-schema version
@FreezeSchema must exist in code for --to-schema version
SchemaMigrationPlan must have a migration stage between versions

Behavior if test file exists:

Does NOT overwrite (preserves user’s custom assertions)
Prints skip message
Use --force to overwrite

Arguments

`--from-schema <VERSION>`, `-f <VERSION>`

Required. Source schema version (e.g., “2.0.0”).

`--to-schema <VERSION>`, `-t <VERSION>`

Required. Target schema version (e.g., “3.0.0”).

Options

`--force`

Overwrite existing test file:

freezeray generate migration-tests -f 2.0.0 -t 3.0.0 --force

Only use --force if you’re sure you want to discard custom assertions you’ve added to the test.

`--config <PATH>`

Path to config file (experimental):

freezeray generate migration-tests -f 2.0.0 -t 3.0.0 --config .freezeray.yml

What Gets Created

// FreezeRay/Tests/MigrateV2_0_0toV3_0_0_Tests.swift
import Testing
import FreezeRay
@testable import MyApp

/// Migration test from v2.0.0 → v3.0.0
///
/// This test verifies that the migration path between these versions works correctly.
///
/// Note: Tests run serially to avoid SwiftData store conflicts
@Suite(.serialized)
struct MigrateV2_0_0toV3_0_0_Tests {
    @Test("Migrate v2.0.0 → v3.0.0")
    func testMigrateV2_0_0toV3_0_0() throws {
        // Test the migration using FreezeRayRuntime
        try FreezeRayRuntime.testMigration(
            from: AppSchemaV2.self,
            to: AppSchemaV3.self,
            migrationPlan: AppMigrations.self
        )

        // TODO: Add data integrity checks here
        // Example:
        // - Verify data is preserved during migration
        // - Check that new fields have default values
        // - Validate relationship updates
        // - Ensure no data loss for critical fields
    }
}

The generated test includes @Suite(.serialized) to fix parallel execution issues that cause SwiftData store conflicts.

Examples

Basic usage (early workflow)

# When starting V3 development
freezeray generate migration-tests --from-schema 2.0.0 --to-schema 3.0.0

# Edit generated test, add assertions
# Implement V3 schema + migration
# Iterate: run test → fix migration → run test

Output:

🔍 Generating migration test: v2.0.0 → v3.0.0...
✅ Generated migration test: MigrateV2_0_0toV3_0_0_Tests.swift
   Edit this file to add custom migration assertions

Short form

freezeray g migration-tests -f 2.0.0 -t 3.0.0

Regenerate (overwrite custom assertions)

freezeray generate migration-tests -f 2.0.0 -t 3.0.0 --force

Output:

✅ Generated migration test: MigrateV2_0_0toV3_0_0_Tests.swift

Common Errors

”No fixtures found for version X.Y.Z”

Cause: Source schema fixtures don’t exist. Fix: Freeze the source version first:

freezeray freeze 2.0.0
freezeray generate migration-tests -f 2.0.0 -t 3.0.0

“No @FreezeSchema found for version X.Y.Z”

Cause: Target schema doesn’t exist in code yet. Fix: Define the target schema:

@FreezeSchema(version: "3.0.0")
enum AppSchemaV3: VersionedSchema {
    // ...
}

Then generate the test:

freezeray generate migration-tests -f 2.0.0 -t 3.0.0

“No SchemaMigrationPlan found in codebase”

Cause: You haven’t defined a migration plan. Fix: Create a migration plan:

enum AppMigrations: SchemaMigrationPlan {
    static var schemas: [any VersionedSchema.Type] {
        [AppSchemaV1.self, AppSchemaV2.self, AppSchemaV3.self]
    }

    static var stages: [MigrationStage] {
        [migrateV1toV2, migrateV2toV3]
    }

    static let migrateV2toV3 = MigrationStage.custom(
        fromVersion: AppSchemaV2.self,
        toVersion: AppSchemaV3.self,
        willMigrate: nil,
        didMigrate: { context in
            // Migration logic
        }
    )
}

Then generate the test:

freezeray generate migration-tests -f 2.0.0 -t 3.0.0

“Migration test already exists”

Cause: You’ve already generated the migration test. Solutions: If you’ve added custom assertions:

# Do nothing - keep your custom test

If you want to start over:

freezeray generate migration-tests -f 2.0.0 -t 3.0.0 --force

Complete Workflow Example

# 1. Ship V2
freezeray freeze 2.0.0

# 2. Start V3 development - generate migration test immediately
freezeray generate migration-tests -f 2.0.0 -t 3.0.0

# 3. Edit generated test, add custom assertions
vim FreezeRay/Tests/MigrateV2_0_0toV3_0_0_Tests.swift

# 4. Implement V3 schema + migration
# (edit schema files, add migration stage)

# 5. Iterate: run tests normally as you develop
# ⌘U in Xcode or:
xcodebuild test -scheme MyApp

# 6. Ship V3
freezeray freeze 3.0.0  # Just generates fixtures + drift test

Key point: You develop with the migration test from the start, not after the fact.

Parallel Execution Fix

All generated tests now use @Suite(.serialized) to prevent parallel execution issues.

Problem (Before)

Migration tests failed when run in parallel (Swift Testing default):

swift test
# ❌ All 3 migration tests fail due to parallel execution

Running individually worked:

swift test --filter MigrateV2toV3
# ✅ Passes

Cause: Tests create/destroy SwiftData stores in temp directories with potential collisions.

Solution (After)

Generated tests now use @Suite(.serialized):

@Suite(.serialized)  // ← Prevents parallel execution
struct MigrateV2_0_0toV3_0_0_Tests {
    @Test func testMigrateV2_0_0toV3_0_0() throws {
        // ...
    }
}

Now tests work in default harness:

swift test
# ✅ All tests pass

Best Practices

1. Generate Migration Tests Early

Generate the migration test when you start working on the migration:

# ✅ Good: Generate early
freezeray generate migration-tests -f 2.0.0 -t 3.0.0
# Edit test, add assertions
# Implement migration
# Iterate until test passes

# ❌ Bad: Generate after implementing
# (implement migration)
# (write custom test)
freezeray freeze 3.0.0  # Conflict!

2. Never Overwrite User Tests

The generate commands never overwrite existing test files by default:

# First time: creates file
freezeray generate migration-tests -f 2.0.0 -t 3.0.0
# ✅ Generated migration test

# Second time: skips
freezeray generate migration-tests -f 2.0.0 -t 3.0.0
# ⚠️  Migration test already exists (preserving custom assertions)

This protects your custom assertions.

3. Use `freeze` for Complete Workflow

For most users, freeze is still the recommended command:

# This is still the easiest workflow
freezeray freeze 1.0.0  # Does everything

Only use generate when you need fine-grained control:

Generate migration tests early ✅
Regenerate specific artifacts ✅
Customize the workflow ✅

4. Commit Generated Tests

Generated tests are yours to maintain:

freezeray generate migration-tests -f 2.0.0 -t 3.0.0

# Add custom assertions
vim FreezeRay/Tests/MigrateV2_0_0toV3_0_0_Tests.swift

# Commit with schema changes
git add FreezeRay/Tests/
git commit -m "Add migration test for V2→V3 with data integrity checks"

Test files evolve with your schema, just like any other test.

What `freeze` Does

The freeze command is simpler than generate - it only creates fixtures and drift tests:

freezeray freeze 3.0.0

Internally equivalent to:

# 1. Generate fixtures (via simulator)
freezeray generate fixtures --schema 3.0.0

# 2. Generate drift test (if doesn't exist)
freezeray generate schema-tests --schema 3.0.0

That’s it! freeze does NOT touch migration tests. Migration tests are managed separately with generate migration-tests.

Requirements

Same as freezeray freeze:

macOS 14+
Xcode 15+
iOS Simulator (iPhone 17 recommended)
Project structure:
- @FreezeSchema(version: "X.X.X") annotations
- Test target for running freeze tests
- Xcode project or Swift Package with iOS target

Next Steps

freeze command

Learn about the convenience freeze command

Testing Migrations

Step-by-step guide for the new migration workflow

Migration Testing Concepts

Understand how migration tests work

Drift Detection

Learn about schema drift detection

​freezeray generate

​Synopsis

​Description

​Subcommands

​migration-tests - Generate migration tests ⭐

​fixtures - Generate frozen fixtures (Advanced)

​schema-tests - Generate drift tests (Advanced)

​Why Use generate migration-tests?

​The Correct Workflow

​generate fixtures

​Synopsis

​Description

​Arguments

​--schema <VERSION>, -s <VERSION>

​Options

​--simulator <NAME>

​--scheme <NAME>

​--force

​--output <PATH>

​--config <PATH>

​What Gets Created

​Examples

​Basic usage

​Short form

​Custom simulator

​Common Errors

​”No @FreezeSchema found for version X.Y.Z”

​“Fixtures already exist”

​generate schema-tests

​Synopsis

​Description

​Arguments

​--schema <VERSION>, -s <VERSION>

​Options

​--force

​--config <PATH>

​What Gets Created

​Examples

​Basic usage

​Short form

​Regenerate (overwrite)

​Common Errors

​”No fixtures found for version X.Y.Z”

​“Test file already exists”

​generate migration-tests

​Synopsis

​Description

​Arguments

​--from-schema <VERSION>, -f <VERSION>

​--to-schema <VERSION>, -t <VERSION>

​Options

​--force

​--config <PATH>

​What Gets Created

​Examples

​Basic usage (early workflow)

​Short form

​Regenerate (overwrite custom assertions)

​Common Errors

​”No fixtures found for version X.Y.Z”

​“No @FreezeSchema found for version X.Y.Z”

​“No SchemaMigrationPlan found in codebase”

​“Migration test already exists”

​Complete Workflow Example

​Parallel Execution Fix

​Problem (Before)

​Solution (After)

​Best Practices

​1. Generate Migration Tests Early

​2. Never Overwrite User Tests

​3. Use freeze for Complete Workflow

​4. Commit Generated Tests

​What freeze Does

​Requirements

​Next Steps

freeze command

Testing Migrations

Migration Testing Concepts

Drift Detection

freezeray generate

Synopsis

Description

Subcommands

`migration-tests` - Generate migration tests ⭐

`fixtures` - Generate frozen fixtures (Advanced)

`schema-tests` - Generate drift tests (Advanced)

Why Use `generate migration-tests`?

The Correct Workflow

generate fixtures

Synopsis

Description

Arguments

`--schema <VERSION>`, `-s <VERSION>`

Options

`--simulator <NAME>`

`--scheme <NAME>`

`--force`

`--output <PATH>`

`--config <PATH>`

What Gets Created

Examples

Basic usage

Short form

Custom simulator

Common Errors

”No @FreezeSchema found for version X.Y.Z”

“Fixtures already exist”

generate schema-tests

Synopsis

Description

Arguments

`--schema <VERSION>`, `-s <VERSION>`

Options

`--force`

`--config <PATH>`

What Gets Created

Examples

Basic usage

Short form

Regenerate (overwrite)

Common Errors

”No fixtures found for version X.Y.Z”

“Test file already exists”

generate migration-tests

Synopsis

Description

Arguments

`--from-schema <VERSION>`, `-f <VERSION>`

`--to-schema <VERSION>`, `-t <VERSION>`

Options

`--force`

`--config <PATH>`

What Gets Created

Examples

Basic usage (early workflow)

Short form

Regenerate (overwrite custom assertions)

Common Errors

”No fixtures found for version X.Y.Z”

“No @FreezeSchema found for version X.Y.Z”

“No SchemaMigrationPlan found in codebase”

“Migration test already exists”

Complete Workflow Example

Parallel Execution Fix

Problem (Before)

Solution (After)

Best Practices

1. Generate Migration Tests Early

2. Never Overwrite User Tests

3. Use `freeze` for Complete Workflow

4. Commit Generated Tests

What `freeze` Does

Requirements

Next Steps