Add BeDefined and NotBeDefined to EnumAssertions (#1888)

Add methods `BeDefined` and `NotBeDefined` to `EnumAssertions`
fluentassertions · Apr 15, 2022 · 192f48c · 192f48c
1 parent db4562b
commit 192f48c
Show file tree

Hide file tree

Showing 10 changed files with 156 additions and 0 deletions.
diff --git a/Src/FluentAssertions/Primitives/EnumAssertions.cs b/Src/FluentAssertions/Primitives/EnumAssertions.cs
@@ -129,6 +129,58 @@ public AndConstraint<TAssertions> Be(TEnum? expected, string because = "", param
             return new AndConstraint<TAssertions>((TAssertions)this);
         }
 
+        /// <summary>
+        /// Asserts that the current value of <typeparamref name="TEnum"/> is defined inside the enum.
+        /// </summary>
+        /// <param name="because">
+        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
+        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
+        /// </param>
+        /// <param name="becauseArgs">
+        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
+        /// </param>
+        public AndConstraint<TAssertions> BeDefined(string because = "", params object[] becauseArgs)
+        {
+            Execute.Assertion
+                .BecauseOf(because, becauseArgs)
+                .WithExpectation("Expected {context:the enum} to be defined in {0}{reason}, ", typeof(TEnum))
+                .ForCondition(Subject is not null)
+                .FailWith("but found <null>.")
+                .Then
+                .ForCondition(Enum.IsDefined(typeof(TEnum), Subject))
+                .FailWith("but it is not.")
+                .Then
+                .ClearExpectation();
+
+            return new AndConstraint<TAssertions>((TAssertions)this);
+        }
+
+        /// <summary>
+        /// Asserts that the current value of <typeparamref name="TEnum"/> is not defined inside the enum.
+        /// </summary>
+        /// <param name="because">
+        /// A formatted phrase as is supported by <see cref="string.Format(string,object[])" /> explaining why the assertion
+        /// is needed. If the phrase does not start with the word <i>because</i>, it is prepended automatically.
+        /// </param>
+        /// <param name="becauseArgs">
+        /// Zero or more objects to format using the placeholders in <paramref name="because" />.
+        /// </param>
+        public AndConstraint<TAssertions> NotBeDefined(string because = "", params object[] becauseArgs)
+        {
+            Execute.Assertion
+                .BecauseOf(because, becauseArgs)
+                .WithExpectation("Did not expect {context:the enum} to be defined in {0}{reason}, ", typeof(TEnum))
+                .ForCondition(Subject is not null)
+                .FailWith("but found <null>.")
+                .Then
+                .ForCondition(!Enum.IsDefined(typeof(TEnum), Subject))
+                .FailWith("but it is.")
+                .Then
+                .ClearExpectation();
+
+            return new AndConstraint<TAssertions>((TAssertions)this);
+        }
+
         /// <summary>
         /// Asserts that the current <typeparamref name="TEnum"/> is exactly equal to the <paramref name="expected"/> value.
         /// </summary>

diff --git a/Tests/Approval.Tests/ApprovedApi/FluentAssertions/net47.verified.txt b/Tests/Approval.Tests/ApprovedApi/FluentAssertions/net47.verified.txt
@@ -1887,6 +1887,7 @@ namespace FluentAssertions.Primitives
         public TEnum? Subject { get; }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum expected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum? expected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> BeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(params TEnum[] validValues) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(System.Collections.Generic.IEnumerable<TEnum> validValues, string because = "", params object[] becauseArgs) { }
         public override bool Equals(object obj) { }
@@ -1899,6 +1900,7 @@ namespace FluentAssertions.Primitives
         public FluentAssertions.AndConstraint<TAssertions> Match(System.Linq.Expressions.Expression<System.Func<TEnum?, bool>> predicate, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum unexpected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum? unexpected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> NotBeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveFlag(TEnum unexpectedFlag, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveSameNameAs<T>(T unexpected, string because = "", params object[] becauseArgs)
             where T :  struct, System.Enum { }

diff --git a/Tests/Approval.Tests/ApprovedApi/FluentAssertions/net6.0.verified.txt b/Tests/Approval.Tests/ApprovedApi/FluentAssertions/net6.0.verified.txt
@@ -1944,6 +1944,7 @@ namespace FluentAssertions.Primitives
         public TEnum? Subject { get; }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum expected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum? expected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> BeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(params TEnum[] validValues) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(System.Collections.Generic.IEnumerable<TEnum> validValues, string because = "", params object[] becauseArgs) { }
         public override bool Equals(object obj) { }
@@ -1956,6 +1957,7 @@ namespace FluentAssertions.Primitives
         public FluentAssertions.AndConstraint<TAssertions> Match(System.Linq.Expressions.Expression<System.Func<TEnum?, bool>> predicate, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum unexpected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum? unexpected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> NotBeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveFlag(TEnum unexpectedFlag, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveSameNameAs<T>(T unexpected, string because = "", params object[] becauseArgs)
             where T :  struct, System.Enum { }

diff --git a/Tests/Approval.Tests/ApprovedApi/FluentAssertions/netcoreapp2.1.verified.txt b/Tests/Approval.Tests/ApprovedApi/FluentAssertions/netcoreapp2.1.verified.txt
@@ -1887,6 +1887,7 @@ namespace FluentAssertions.Primitives
         public TEnum? Subject { get; }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum expected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum? expected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> BeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(params TEnum[] validValues) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(System.Collections.Generic.IEnumerable<TEnum> validValues, string because = "", params object[] becauseArgs) { }
         public override bool Equals(object obj) { }
@@ -1899,6 +1900,7 @@ namespace FluentAssertions.Primitives
         public FluentAssertions.AndConstraint<TAssertions> Match(System.Linq.Expressions.Expression<System.Func<TEnum?, bool>> predicate, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum unexpected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum? unexpected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> NotBeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveFlag(TEnum unexpectedFlag, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveSameNameAs<T>(T unexpected, string because = "", params object[] becauseArgs)
             where T :  struct, System.Enum { }

diff --git a/Tests/Approval.Tests/ApprovedApi/FluentAssertions/netcoreapp3.0.verified.txt b/Tests/Approval.Tests/ApprovedApi/FluentAssertions/netcoreapp3.0.verified.txt
@@ -1887,6 +1887,7 @@ namespace FluentAssertions.Primitives
         public TEnum? Subject { get; }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum expected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum? expected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> BeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(params TEnum[] validValues) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(System.Collections.Generic.IEnumerable<TEnum> validValues, string because = "", params object[] becauseArgs) { }
         public override bool Equals(object obj) { }
@@ -1899,6 +1900,7 @@ namespace FluentAssertions.Primitives
         public FluentAssertions.AndConstraint<TAssertions> Match(System.Linq.Expressions.Expression<System.Func<TEnum?, bool>> predicate, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum unexpected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum? unexpected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> NotBeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveFlag(TEnum unexpectedFlag, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveSameNameAs<T>(T unexpected, string because = "", params object[] becauseArgs)
             where T :  struct, System.Enum { }

diff --git a/Tests/Approval.Tests/ApprovedApi/FluentAssertions/netstandard2.0.verified.txt b/Tests/Approval.Tests/ApprovedApi/FluentAssertions/netstandard2.0.verified.txt
@@ -1839,6 +1839,7 @@ namespace FluentAssertions.Primitives
         public TEnum? Subject { get; }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum expected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum? expected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> BeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(params TEnum[] validValues) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(System.Collections.Generic.IEnumerable<TEnum> validValues, string because = "", params object[] becauseArgs) { }
         public override bool Equals(object obj) { }
@@ -1851,6 +1852,7 @@ namespace FluentAssertions.Primitives
         public FluentAssertions.AndConstraint<TAssertions> Match(System.Linq.Expressions.Expression<System.Func<TEnum?, bool>> predicate, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum unexpected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum? unexpected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> NotBeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveFlag(TEnum unexpectedFlag, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveSameNameAs<T>(T unexpected, string because = "", params object[] becauseArgs)
             where T :  struct, System.Enum { }

diff --git a/Tests/Approval.Tests/ApprovedApi/FluentAssertions/netstandard2.1.verified.txt b/Tests/Approval.Tests/ApprovedApi/FluentAssertions/netstandard2.1.verified.txt
@@ -1887,6 +1887,7 @@ namespace FluentAssertions.Primitives
         public TEnum? Subject { get; }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum expected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> Be(TEnum? expected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> BeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(params TEnum[] validValues) { }
         public FluentAssertions.AndConstraint<TAssertions> BeOneOf(System.Collections.Generic.IEnumerable<TEnum> validValues, string because = "", params object[] becauseArgs) { }
         public override bool Equals(object obj) { }
@@ -1899,6 +1900,7 @@ namespace FluentAssertions.Primitives
         public FluentAssertions.AndConstraint<TAssertions> Match(System.Linq.Expressions.Expression<System.Func<TEnum?, bool>> predicate, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum unexpected, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotBe(TEnum? unexpected, string because = "", params object[] becauseArgs) { }
+        public FluentAssertions.AndConstraint<TAssertions> NotBeDefined(string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveFlag(TEnum unexpectedFlag, string because = "", params object[] becauseArgs) { }
         public FluentAssertions.AndConstraint<TAssertions> NotHaveSameNameAs<T>(T unexpected, string because = "", params object[] becauseArgs)
             where T :  struct, System.Enum { }

diff --git a/Tests/FluentAssertions.Specs/Primitives/EnumAssertionSpecs.cs b/Tests/FluentAssertions.Specs/Primitives/EnumAssertionSpecs.cs
@@ -791,5 +791,84 @@ public void An_enum_cannot_be_part_of_a_null_list()
         }
 
         #endregion
+
+        #region Be defined / Not be defined
+
+        [Fact]
+        public void A_valid_entry_of_an_enum_is_defined()
+        {
+            // Arrange
+            var dayOfWeek = (DayOfWeek)1;
+
+            // Act / Assert
+            dayOfWeek.Should().BeDefined();
+        }
+
+        [Fact]
+        public void If_a_value_casted_to_an_enum_type_and_it_does_not_exist_in_the_enum_it_throws()
+        {
+            // Arrange
+            var dayOfWeek = (DayOfWeek)999;
+
+            // Act
+            Action act = () => dayOfWeek.Should().BeDefined("we want to test the failure {0}", "message");
+
+            // Assert
+            act.Should().Throw<XunitException>()
+                .WithMessage("Expected *to be defined in*failure message*, but it is not*");
+        }
+
+        [Fact]
+        public void A_null_entry_of_an_enum_throws()
+        {
+            // Arrange
+            MyEnum? subject = null;
+
+            // Act
+            Action act = () => subject.Should().BeDefined();
+
+            // Assert
+            act.Should().Throw<XunitException>()
+                .WithMessage("Expected *to be defined in*, but found <null>.");
+        }
+
+        [Fact]
+        public void An_invalid_entry_of_an_enum_is_not_defined_passes()
+        {
+            // Arrange
+            var dayOfWeek = (DayOfWeek)999;
+
+            // Act / Assert
+            dayOfWeek.Should().NotBeDefined();
+        }
+
+        [Fact]
+        public void A_valid_entry_of_an_enum_is_not_defined_fails()
+        {
+            // Arrange
+            var dayOfWeek = (DayOfWeek)1;
+
+            // Act
+            Action act = () => dayOfWeek.Should().NotBeDefined();
+
+            // Assert
+            act.Should().Throw<XunitException>()
+                .WithMessage("Did not expect*to be defined in*, but it is.");
+        }
+
+        [Fact]
+        public void A_null_value_of_an_enum_is_not_defined_and_throws()
+        {
+            // Arrange
+            MyEnum? subject = null;
+
+            // Act
+            Action act = () => subject.Should().NotBeDefined();
+
+            // Assert
+            act.Should().Throw<XunitException>()
+                .WithMessage("Did not expect *to be defined in*, but found <null>.");
+        }
+        #endregion
     }
 }
diff --git a/docs/_pages/enums.md b/docs/_pages/enums.md
@@ -42,3 +42,11 @@ Lastly, if you want to verify than an enum has a specific integral value, you ca
 MyEnum.One.Should().HaveValue(1);
 MyEnum.One.Should().NotHaveValue(2);
 ```
+
+```csharp
+var myEnum = (MyEnum)1;
+myEnum.Should().BeDefined();
+
+myEnum = (MyEnum)99;
+myEnum.Should().NotBeDefined();
+```
diff --git a/docs/_pages/releases.md b/docs/_pages/releases.md
@@ -9,6 +9,11 @@ sidebar:
 
 ## Unreleased
 
+### What's new
+* Add `BeDefined` and `NotBeDefined` to assert on existence of an enum value - [#1888](https://github.com/fluentassertions/fluentassertions/pull/1888)
+
+## 6.6.0
+
 ### What's New
 * Annotated `[Not]MatchRegex(string)` with `[StringSyntax("Regex")]` which IDEs can use to colorize the regular expression argument - [#1816](https://github.com/fluentassertions/fluentassertions/pull/1816)
 * Added support for .NET6 `DateOnly` struct - [#1844](https://github.com/fluentassertions/fluentassertions/pull/1844)