fluentassertions/fluentassertions
Fluentassertions
FluentAssertions is a library of extension methods for .NET that provides a human-readable syntax for verifying expectations in unit tests. It serves as a validation layer that integrates with MSTest, NUnit, and xUnit to throw framework-specific exceptions upon assertion failure.
The project includes a structural equivalency engine that performs deep member-by-member validation of .NET objects using configurable matching rules. It is designed for test-driven and behavior-driven development by generating descriptive failure messages that explain the difference between actual and expected results.
The library covers a broad range of capabilities, including object state verification, complex object validation for nested data structures, and the ability to batch multiple assertion failures into a single report. It also provides extensibility through custom assertion definitions, global configuration settings, and a provider-based system for customizing how values are formatted in failure messages.
Features
- .NET Testing Ecosystem - Provides a fluent assertion library specifically designed for the .NET unit testing ecosystem.
- Test Expectation Frameworks - Provides a comprehensive mechanism to define expected outcomes for unit tests and generate descriptive failure messages.
- Extension Methods - Uses .NET extension methods to provide a fluent, natural-language interface for chaining validation logic.
- Structural Equivalency Engines - Provides a deep member-by-member validation engine for .NET objects with configurable matching rules.
- Comparison Pipeline Customization - Provides a configurable pipeline to inject custom matching rules and member filters into the object equivalency engine.
- Nested Object Validation - Implements recursive validation of nested objects and collections through structural equivalency rules.
- Framework-Specific Exception Mapping - Automatically detects the active unit test framework to throw the required framework-specific exception.
- Reflection-Based Comparisons - Recursively inspects object graphs using reflection to perform deep member-by-member structural comparison.
- Fluent Assertion Chaining - Links multiple validation rules in a sequence to maintain a fluent chain of expectations on a single subject.
- Fluent Assertions - Provides a library of extension methods for .NET that uses a fluent, natural-language syntax for assertions.
- Custom Failure Messaging - Generates detailed, human-readable error descriptions that explain the exact difference between expected and actual results.
- Object State Matchers - Provides compound expectations and matchers to validate that the internal state of objects meets specific criteria.
- Structural Equivalency Configurations - Provides a configurable engine to control how complex objects are compared using value semantics or member comparisons.
- Test Framework Integrations - Integrates with MSTest, NUnit, and xUnit to ensure compatible exception types are thrown upon failure.
- Testing Framework Integrations - Integrates with multiple .NET testing frameworks to ensure the correct framework-specific exceptions are thrown on failure.
- Variable Name Extraction - Parses calling method metadata to include variable names in failure messages for better developer diagnostics.
- Value Formatting Providers - Implements a provider-based system to convert complex objects into human-readable strings during assertion failures.
- Deferred Failure Strategies - Gathers multiple assertion failures within a scope and reports them as a single aggregate exception.
- Assertion Grouping - Groups several checks into a single scope to report all failures collectively instead of halting at the first error.
- Collection Equivalency Assertions - Provides options to verify if collections contain the same elements regardless of or sensitive to their order.
- Custom Matching Steps - Enables insertion of custom logic into the structural comparison plan for specialized object matching.
- Custom Assertions - Enables the definition of new, specialized validation methods using a fluent API with custom failure messages.
- Source-Based Subject Identification - Extracts variable names from source code to include the specific name of the object under test in failure messages.
- Test Result Reporters - Generates descriptive and precise failure messages to help developers identify differences between actual and expected results.
- Test Assertion Extensions - Allows the addition of custom matchers and validation rules to handle domain-specific requirements.
- Member Comparison Filters - Allows specifying which fields and properties should be included or excluded during object comparisons.
- Failure Batching - FluentAssertions collects multiple failed expectations within a defined scope and reports them as a single combined exception.
- Test-Driven Development Workflows - Facilitates TDD and BDD cycles by translating failed expectations into descriptive, human-readable failure messages.
- Test-Driven Development Workflows - Supports TDD and BDD workflows by providing human-readable expectations and descriptive failure messages.
- Testing - Fluent assertion library for tests.
- Test-Frameworks - Fluent extension methods for specifying test outcomes.
