Changelog for mockcat

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to the Haskell Package Versioning Policy.

[1.4.0.0] - 2026-01-10

Changed

• Breaking Change: Removed the verify fallback mechanism that searched thread history when StableName lookup failed.
  • Impact: Strict verification is now enforced. Tests using shouldBeCalled or related matchers will now deterministically fail if the mock function's identity cannot be strictly resolved (e.g., in some HPC/Coverage environments without proper handling), rather than attempting to guess the intent.
  • Motivation: To ensure absolute confidence in test results and support reliable HPC coverage analysis.

Improved

• HPC Code Coverage Support: The library and test suite are now fully compatible with stack test --coverage.
  • Verification logic has been hardened to handle HPC instrumentation.
  • The test suite now automatically detects HPC mode and skips only those tests that strictly depend on StableName identity (which is inherently unstable under HPC), ensuring the rest of the suite runs safely.
• Test Suite Modernization: Refactored Property-based tests and WithMockIO specs to use the expects pattern (definition-time expectation). This makes them robust enough to strictly verify behavior even in HPC environments.
• Granularity: Improved module organization in Spec.hs for better maintainability.

[1.3.3.0] - 2026-01-04

Added

• Type Families Support: deriveMockInstances now supports type classes containing Associated Type Families.
• Improved withMockIO: withMockIO now enables direct execution of IO actions within mock contexts without liftIO.

[1.3.2.0] - 2026-01-04

Added

• New Derivation Macros:
  • deriveMockInstances: Automatically derives MockT instances for user-defined "Capability" type classes (e.g., MonadLogger). It lifts operations to the base monad.
    • Note: Type Families are currently not supported.
  • deriveNoopInstance: Generates "No-op" instances where methods (returning m ()) do nothing. Useful for ignoring specific interactions (e.g., MonadAuditor).

Improved

• Compile-Time Verification: Enhanced robustness of internal verification scripts (verify_th_errors.sh) to ensure consistent error reporting across GHC versions.
• Documentation: Clarified "Capability vs. Control" design philosophy and limitations regarding Type Families in deriveMockInstances.

[1.3.1.0] - 2026-01-03

Added

• New Parameter Matcher: Introduced when and when_ as the primary functions for condition-based matching.
  • These replace expect and expect_ to improve readability (e.g., mock (when (>5) ~> True) reads naturally as "mock when > 5").

Changed

• Renaming / Deprecation: expect and expect_ have been renamed to when and when_.
  • The old expect and expect_ are now DEPRECATED and will trigger a compiler warning. They will be removed in a future major release.
• Documentation: Updated when / when_ usage and added guidance on resolving name collisions with Control.Monad.when.

[1.3.0.0] - 2026-01-03

Added

• Type-Safe Verification Result: Generated mock helpers now return MockResult params. This type carries parameter information, enabling robust type inference and compile-time safety checks when using declarative verification (expects).
  • This change is part of an ongoing effort to make misuse of mocks impossible at the type level.

Changed

• Breaking Change: Due to the introduction of MockResult, generated mock helpers (e.g., _myMethod) no longer return the mock function itself (MockT m (FunctionType)).
  • Code that previously relied on capturing the returned function (e.g., fn <- _myMethod ...) will need to be updated.
• Refactoring: Reorganized internal test verification logic to utilize MockResult properties.
• Internal: Refactored test suite organization for better maintainability.

[1.2.1.0] - 2026-01-01

Added

• Dynamic Language Extension Detection: mockcat now automatically identifies and requests only necessary extensions (e.g., MultiParamTypeClasses, UndecidableInstances) based on the target class definition.
• Granular Extension Optimization: Simple multi-parameter type classes no longer require AllowAmbiguousTypes or FunctionalDependencies unless they are actually used.

Fixed

• Resolved NoVerification scope issues in Template Haskell generated code.
• Resolved ambiguous any occurrences in internal Template Haskell logic.
• Fixed several typos in Template Haskell error messages.

[1.2.0.0] - 2025-12-31

Changed

• Breaking Change: Changed the fixity of expects operator to infixl 0 to resolve precedence issues with $.
  • Impact: Code using mock $ ... expects ... will now fail to compile.
  • Migration: Wrap the mock definition in parentheses: mock (... ~> ...) expects ....
• Breaking Change: expects now strictly enforces that it can only be applied to a mock creation action (m fn).
  • Attempting to apply expects directly to a MockSpec (e.g. (any ~> 1) expects ...) or an already instantiated function will result in a compile-time TypeError.
• Removed redundant Typeable constraints from expects, enabling cleaner builds on GHC 9.8+.

[1.1.0.0] - 2025-12-29

Added

• HPC Coverage Support: Verification logic now robustly handles unstable StableNames caused by HPC instrumentation (stack test --coverage).
• Optimization Hardening: Protected verification logic against GHC optimizations (CSE/LICM) to ensure stable tests in optimized builds.

Changed

• Automatic History Reset: runMockT and withMock now strictly scope mock history. History is automatically reset to prevent interference between sequential tests or Property-Based Testing iterations.

[1.0.0.0] - 2025-12-24

Changed

• DSL Reboot: Replaced |> with ~> as the primary parameter chain operator (representing the "mock arrow").
• Terminology Shift: Standardized terminology to "called" instead of "applied" throughout the library and error messages.
• Simplified creating/stubbing API: f <- mock $ ... is now the canonical way.
• Expanded structural diffing support for nested records and lists.
• Unified verification API: All verification is now handled via shouldBeCalled.
• Strict by Default: makeMock and makePartialMock now default to strict return values (implicit monadic return is disabled). makeAutoLiftMock was introduced for the previous behavior.

Added

• Deep Structural Diff: Enhanced error messages with precise caret pointers for complex nested data structures.
• STM-based concurrency for mock registration and call recording.
• Infinite arity support for mock/stub building.

Removed

• Backward compatibility with 0.x.x APIs (stubFn, createMock, applied, etc.).
• makeMockWithOptions, makePartialMockWithOptions, and MockOptions (internalized to simplify API).

Migration Guide (0.x -> 1.0)

This release is a complete reboot. Previous code will break.

1. Operator Change: Replace |> with ~>.

   -- Old
   createStubFn $ "arg" |> "result"
   
   -- New
   stub $ "arg" ~> "result"
   

2. Mock Creation: Use mock / stub instead of createMock / createStubFn.

   -- Old
   f <- createMock $ "arg" |> "result"
   
   -- New
   f <- mock $ "arg" ~> "result"
   

3. Verification: Use shouldBeCalled (unified API).

   -- Old
   f `shouldApplyTo` "arg"
   
   -- New
   f `shouldBeCalled` "arg"
   

4. Template Haskell Generics: makeMock is now strict by default (requires explicit pure for IO actions).

   • Use makeAutoLiftMock for old implicit behavior.
   • Or stick to makeMock and add pure to your return values.

0.6.0.0

Changed

• Removed the upper limit on variable arguments when creating stub functions. Previously, there was a restriction on the maximum number of arguments, but this limitation has been removed, allowing stub functions to accept an arbitrary number of arguments.

0.5.5.0

Added

• Aliases expectApplyTimes and expectNever (preferred names) for pre-run expectation declarations.

Documentation

• README (EN/JA) now recommends expectApplyTimes / expectNever over legacy applyTimesIs / neverApply.
• Clarified that expectApplyTimes n is the canonical form; expectNever is sugar for expectApplyTimes 0.

Notes

• Legacy names remain exported for backward compatibility (no deprecation pragma yet). They may receive a soft deprecation notice in a future minor release after community feedback.

0.5.4.0

Added

• Parallel execution support (verified counting under concurrency, stress tests).
• Verification helpers: applyTimesIs, neverApply.

Changed

• Refactored MockT from StateT to ReaderT (TVar [Definition]) architecture.
• Simplified Template Haskell generated constraints.

Fixed

• Race causing lost/double count in concurrent stub applications (strict modifyTVar').

Removed

• unsafePerformIO in TH-generated code.

Internal

• Introduced MonadMockDefs abstraction.

0.5.3.0

Added

• MonadUnliftIO instance for MockT (initial groundwork for later parallel support).