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Meziantou.Framework.Assertions

v2.0.0
net10.0net11.0

Assertion helpers for .NET tests

meziantou
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Published
Jul 5, 2026
3mo ago
Total Downloads
14.0K
14,020

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dotnet add package Meziantou.Framework.Assertions --version 2.0.0
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.NET
net10.0net11.0

README

Meziantou.Framework.Assertions

Assertion helpers for .NET tests.

Assertion methods

Assert provides the following assertion methods:

  • True: Asserts a condition is true.
  • False: Asserts a condition is false.
  • Null: Asserts a value is null.
  • NotNull: Asserts a value is not null and returns it.
  • Same: Asserts two references point to the same instance.
  • NotSame: Asserts two references are different instances.
  • Equal: Asserts two values are equal.
  • NotEqual: Asserts two values are not equal.
  • EqualUnordered: Asserts two sequences contain the same values regardless of order.
  • NotEqualUnordered: Asserts two sequences differ when compared without ordering.
  • Equivalent: Asserts two objects are equal by recursively comparing members.
  • NotEquivalent: Asserts two objects are structurally different.
  • IsType: Asserts a value is exactly of the specified type and returns it.
  • IsNotType: Asserts a value is not exactly of the specified type.
  • IsAssignableTo: Asserts a value is assignable to the specified type and returns it.
  • IsNotAssignableTo: Asserts a value is not assignable to the specified type.
  • InRange: Asserts a value is within the inclusive range.
  • NotInRange: Asserts a value is outside the inclusive range.
  • StartsWith: Asserts text or sequence starts with an expected prefix.
  • EndsWith: Asserts text or sequence ends with an expected suffix.
  • DoesNotStartWith: Asserts text or sequence does not start with a prefix.
  • DoesNotEndWith: Asserts text or sequence does not end with a suffix.
  • Contains: Asserts a value, key, predicate, or subsequence is present.
  • DoesNotContain: Asserts a value, key, predicate, or subsequence is not present.
  • Matches: Asserts text matches a regular expression.
  • DoesNotMatch: Asserts text does not match a regular expression.
  • All: Asserts all items in a collection satisfy an assertion.
  • Collection: Asserts collection items match a list of inspectors.
  • Distinct: Asserts all items in a sequence are distinct.
  • NotDistinct: Asserts a sequence contains duplicate items.
  • Empty: Asserts a collection or sequence is empty.
  • NotEmpty: Asserts a collection or sequence is not empty.
  • Single: Asserts a sequence has exactly one item and returns it.
  • HasCount: Asserts a collection has an exact count.
  • DoesNotHaveCount: Asserts a collection count differs from the specified count.
  • HasCountGreaterThan: Asserts a collection count is greater than a value.
  • HasCountGreaterThanOrEqual: Asserts a collection count is greater than or equal to a value.
  • HasCountLessThan: Asserts a collection count is less than a value.
  • HasCountLessThanOrEqual: Asserts a collection count is less than or equal to a value.
  • ProperSubset: Asserts a set is a proper subset of another set.
  • NotProperSubset: Asserts a set is not a proper subset of another set.
  • ProperSuperset: Asserts a set is a proper superset of another set.
  • NotProperSuperset: Asserts a set is not a proper superset of another set.
  • Throws: Asserts a specific exception type is thrown and returns it.
  • ThrowsAny: Asserts an exception assignable to the specified type is thrown and returns it.
  • ThrowsAsync: Asserts a specific exception type is thrown by an async delegate.
  • ThrowsAnyAsync: Asserts an assignable exception type is thrown by an async delegate.
  • DoesNotThrow: Asserts a delegate completes without throwing.
  • DoesNotThrowAny: Asserts a delegate completes without throwing any exception type.
  • Raise: Asserts a specific event is raised and captures event data.
  • RaiseAny: Asserts an event with a compatible event args type is raised.
  • DoesNotRaise: Asserts a specific event is not raised.
  • DoesNotRaiseAny: Asserts no compatible event is raised.
  • Fail: Fails the test with a custom message.

Use as the default Assert class

You can override the Assert type used in your tests with a global alias:

<Using Include="Meziantou.Framework.Assertions.Assert" Alias="Assert" />

or:

global using Assert = Meziantou.Framework.Assertions.Assert;

Analyzer rules

The package ships analyzers and code fixes to help write clearer assertions.

Id Category Description Severity Enabled
MFAS0001 Assertions Pass the expected value before the actual value Warning ✔️
MFAS0002 Assertions Use Assert.Same instead of Assert.ReferenceEquals Error ✔️
MFAS0003 Assertions Do not use Assert.IsType with static or abstract types Error ✔️
MFAS0004 Assertions Use Assert.Empty for zero count checks Warning ✔️
MFAS0005 Assertions Use specialized count assertions Warning ✔️
MFAS0006 Assertions Use Assert.Null for null comparisons Warning ✔️
MFAS0007 Assertions Use Assert.NotNull for null comparisons Warning ✔️
MFAS0008 Assertions Do not use Assert.Null with value types Error ✔️
MFAS0009 Assertions Do not use Assert.NotNull with value types Error ✔️
MFAS0010 Assertions Do not use Assert.Same with value types Error ✔️
MFAS0011 Assertions Do not use Assert.NotSame with value types Error ✔️
MFAS0012 Assertions Use Assert.IsAssignableTo for type pattern checks Warning ✔️
MFAS0013 Assertions Use Assert.IsNotAssignableTo for type pattern checks Warning ✔️
MFAS0014 Assertions Use Assert.Matches instead of Assert.True(Regex.IsMatch(...)) Warning ✔️
MFAS0015 Assertions Use Assert.DoesNotMatch instead of Assert.False(Regex.IsMatch(...)) Warning ✔️
MFAS0016 Assertions Use Assert.Contains instead of Assert.True(string.Contains(...)) Warning ✔️
MFAS0017 Assertions Use Assert.DoesNotContain instead of Assert.False(string.Contains(...)) Warning ✔️
MFAS0018 Assertions Use Assert.StartsWith instead of Assert.True(string.StartsWith(...)) Warning ✔️
MFAS0019 Assertions Use Assert.DoesNotStartWith instead of Assert.False(string.StartsWith(...)) Warning ✔️
MFAS0020 Assertions Use Assert.EndsWith instead of Assert.True(string.EndsWith(...)) Warning ✔️
MFAS0021 Assertions Use Assert.DoesNotEndWith instead of Assert.False(string.EndsWith(...)) Warning ✔️
MFAS0022 Assertions Use Assert.Contains instead of Assert.True(collection.Contains(...)) Warning ✔️
MFAS0023 Assertions Use Assert.DoesNotContain instead of Assert.False(collection.Contains(...)) Warning ✔️
MFAS0024 Assertions Use Assert.Contains instead of Assert.True(collection.Any(...)) Warning ✔️
MFAS0025 Assertions Use Assert.DoesNotContain instead of Assert.False(collection.Any(...)) Warning ✔️
MFAS0026 Assertions Use Assert.All instead of Assert.True(collection.All(...)) Warning ✔️
MFAS0027 Assertions Use Assert.DoesNotAll instead of Assert.False(collection.All(...)) Warning ✔️

Changes from Previous Version

v1.0.1v2.0.0
Removed Frameworks
net8.0net9.0

Adoption Assessment

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Compatibility metadata lists 2 target frameworks; confirm the exact target used by your application.

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