Merge pull request #368 from ssiko/ShouldHaveSingleItem

Added ShouldHaveSingleItem for Enumerables.

src/DocumentationExamples/CodeExamples/EnumerableShouldHaveSingleItemExamples.ShouldHaveSingleItem.codeSample.approved.txt

@@ -0,0 +1,4 @@
+var maggie = new Person() { Name = "Maggie" };
+var homer = new Person() { Name = "Homer" };
+var simpsonsBabies = new List<Person>() { homer, maggie };
+simpsonsBabies.ShouldHaveSingleItem();

src/DocumentationExamples/CodeExamples/EnumerableShouldHaveSingleItemExamples.ShouldHaveSingleItem.exceptionText.approved.txt

@@ -0,0 +1,5 @@
+simpsonsBabies
+    should have single item but had
+2
+    items and was
+[Homer, Maggie]

src/DocumentationExamples/DocumentationExamples.csproj

@@ -81,6 +81,7 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="EnumerableShouldHaveSingleItemExamples.cs" />
     <Compile Include="ShouldSatisfyAllConditionsExamples.cs" />
     <Compile Include="ShouldNotThrowExamples.cs" />
     <Compile Include="ShouldCompleteInExamples.cs" />

src/DocumentationExamples/EnumerableShouldHaveSingleItemExamples.cs

@@ -0,0 +1,30 @@
+using System.Collections.Generic;
+using Shouldly;
+using Simpsons;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace DocumentationExamples
+{
+    public class EnumerableShouldHaveSingleItemExamples
+    {
+        readonly ITestOutputHelper _testOutputHelper;
+
+        public EnumerableShouldHaveSingleItemExamples(ITestOutputHelper testOutputHelper)
+        {
+            _testOutputHelper = testOutputHelper;
+        }
+
+        [Fact]
+        public void ShouldHaveSingleItem()
+        {
+            DocExampleWriter.Document(() =>
+            {
+                var maggie = new Person() { Name = "Maggie" };
+                var homer = new Person() { Name = "Homer" };
+                var simpsonsBabies = new List<Person>() { homer, maggie };
+                simpsonsBabies.ShouldHaveSingleItem();
+            }, _testOutputHelper);
+        }
+    }
+}

src/Shouldly.Shared/MessageGenerators/ShouldHaveSingleItemMessageGenerator.cs

@@ -0,0 +1,41 @@
+using System;
+using Shouldly.DifferenceHighlighting;
+using System.Collections;
+using System.Linq;
+
+namespace Shouldly.MessageGenerators
+{
+    internal class ShouldHaveSingleItemMessageGenerator : ShouldlyMessageGenerator
+    {
+        const string ShouldBeAssertion = "ShouldHaveSingleItem";
+
+        public override bool CanProcess(IShouldlyAssertionContext context)
+        {
+            return context.ShouldMethod.Equals(ShouldBeAssertion, StringComparison.OrdinalIgnoreCase);
+        }
+
+        public override string GenerateErrorMessage(IShouldlyAssertionContext context)
+        {
+            var codePart = context.CodePart;
+            var expected = context.Expected.ToStringAwesomely();
+            var count = (context.Expected ?? Enumerable.Empty<object>()).As<IEnumerable>().Cast<object>().Count();
+            if (codePart != "null")
+            {
+                return
+    $@"{codePart}
+    {context.ShouldMethod.PascalToSpaced()} but had
+{count}
+    items and was
+{expected}";
+            }
+            else
+            {
+                return
+$@"{expected}
+    {context.ShouldMethod.PascalToSpaced()} but had
+{count}
+    items";
+            }
+        }
+    }
+}

src/Shouldly.Shared/Shouldly.Shared.projitems

@@ -70,6 +70,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)MessageGenerators\ShouldBeNullOrEmptyMessageGenerator.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)MessageGenerators\ShouldBeNullOrWhiteSpaceMessageGenerator.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)MessageGenerators\ShouldBePositiveMessageGenerator.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)MessageGenerators\ShouldHaveSingleItemMessageGenerator.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)MessageGenerators\ShouldBeSubsetOfMessageGenerator.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)MessageGenerators\ShouldBeTypeMessageGenerator.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)MessageGenerators\ShouldBeUniqueMessageGenerator.cs" />

src/Shouldly.Shared/ShouldlyExtensionMethods/ShouldBeEnumerableTestExtensions.cs

@@ -127,7 +127,7 @@ public static void ShouldBeEmpty<T>(this IEnumerable<T> actual, string customMes
 
         public static void ShouldBeEmpty<T>(this IEnumerable<T> actual, [InstantHandle] Func<string> customMessage)
         {
-            if (actual == null || (actual != null && actual.Count() != 0))
+            if (actual == null || actual.Any())
                 throw new ShouldAssertException(new ExpectedShouldlyMessage(actual, customMessage).ToString());
         }
 
@@ -143,10 +143,28 @@ public static void ShouldNotBeEmpty<T>(this IEnumerable<T> actual, string custom
 
         public static void ShouldNotBeEmpty<T>(this IEnumerable<T> actual, [InstantHandle] Func<string> customMessage)
         {
-            if (actual == null || actual != null && !actual.Any())
+            if (actual == null || !actual.Any())
                 throw new ShouldAssertException(new ExpectedShouldlyMessage(actual, customMessage).ToString());
         }
 
+        public static T ShouldHaveSingleItem<T>(this IEnumerable<T> actual)
+        {
+            return ShouldHaveSingleItem(actual, () => null);
+        }
+
+        public static T ShouldHaveSingleItem<T>(this IEnumerable<T> actual, string customMessage)
+        {
+            return ShouldHaveSingleItem(actual, () => customMessage);
+        }
+
+        public static T ShouldHaveSingleItem<T>(this IEnumerable<T> actual, [InstantHandle] Func<string> customMessage)
+        {
+            if (actual == null || actual.Count() != 1)
+                throw new ShouldAssertException(new ExpectedShouldlyMessage(actual, customMessage).ToString());
+
+            return actual.Single();
+        }
+
         public static void ShouldContain(this IEnumerable<float> actual, float expected, double tolerance)
         {
             ShouldContain(actual, expected, tolerance, () => null);

src/Shouldly.Shared/ShouldlyMessage.cs

@@ -236,6 +236,7 @@ internal abstract class ShouldlyMessage
             new ShouldBeIgnoringOrderMessageGenerator(), 
             new ShouldSatisfyAllConditionsMessageGenerator(),
             new ShouldBeSubsetOfMessageGenerator(),
+            new ShouldHaveSingleItemMessageGenerator(),
             new ShouldBeBooleanMessageGenerator(),
             new ShouldNotThrowMessageGenerator(),
             new ShouldNotMatchMessageGenerator(),

src/Shouldly.Tests.Shared/ShouldHaveSingleItem/ArrayScenario.cs

@@ -0,0 +1,43 @@
+using Xunit;
+using System.Collections.Generic;
+using Shouldly.Tests.Strings;
+
+namespace Shouldly.Tests.Shared.ShouldHaveSingleItem
+{
+    public class ArrayScenario
+    {
+
+        [Fact]
+        public void ArrayScenarioShouldFail()
+        {
+            Verify.ShouldFail(() =>
+new[] { 1, 2 }.ShouldHaveSingleItem("Some additional context"),
+
+errorWithSource:
+@"new[] { 1, 2 }
+    should have single item but had
+2
+    items and was
+[1, 2]
+
+Additional Info:
+    Some additional context",
+
+errorWithoutSource:
+@"[1, 2]
+    should have single item but had
+2
+    items
+
+Additional Info:
+    Some additional context");            
+        }
+
+        [Fact]
+        public void ShouldPass()
+        {
+            int result = new[] { 1 }.ShouldHaveSingleItem();
+            result.ShouldBe(1);
+        }
+    }
+}

src/Shouldly.Tests.Shared/Shouldly.Tests.Shared.projitems

@@ -75,6 +75,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)ShouldBeSameAs\BasicScenario.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShouldBeSameAs\BoxedIntScenario.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShouldBeSameAs\SameListDifferentInstanceScenario.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)ShouldHaveSingleItem\ArrayScenario.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShouldBeSubsetOf\DecimalArrayScenario.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShouldBeSubsetOf\FloatArrayScenario.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ShouldBeSubsetOf\IntegerArrayScenario.cs" />

src/ShouldlyConvention.Tests/ApprovePublicAPI.ShouldlyApi.approved.cs

@@ -1,4 +1,4 @@
-[assembly: System.Runtime.CompilerServices.InternalsVisibleToAttribute(@"Shouldly.Tests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100e3aa2a20de74f360af7742a2b21b409d570722b14ec3d14283a0d89e8147855d1097fbf084d7b3a8bbd1bfe50a589254ce50ee70bf530f23e280e13eeeff3813a6863a8dffa604f6a749628fc82f449e8a5717a4a70787a3f55547f1a2ad8fffafe8945f327dc7a66887b81c7bb5b8f06651f51a7e640e150a7c4cf1049041ca")]
+[assembly: System.Runtime.CompilerServices.InternalsVisibleToAttribute(@"Shouldly.Tests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100e3aa2a20de74f360af7742a2b21b409d570722b14ec3d14283a0d89e8147855d1097fbf084d7b3a8bbd1bfe50a589254ce50ee70bf530f23e280e13eeeff3813a6863a8dffa604f6a749628fc82f449e8a5717a4a70787a3f55547f1a2ad8fffafe8945f327dc7a66887b81c7bb5b8f06651f51a7e640e150a7c4cf1049041ca")]
 [assembly: System.Runtime.Versioning.TargetFrameworkAttribute(".NETFramework,Version=v4.0", FrameworkDisplayName=".NET Framework 4")]
 
 namespace Shouldly
@@ -181,6 +181,9 @@ public class static ShouldBeEnumerableTestExtensions
         public static void ShouldContain(this System.Collections.Generic.IEnumerable<double> actual, double expected, double tolerance) { }
         public static void ShouldContain(this System.Collections.Generic.IEnumerable<double> actual, double expected, double tolerance, string customMessage) { }
         public static void ShouldContain(this System.Collections.Generic.IEnumerable<double> actual, double expected, double tolerance, [JetBrains.Annotations.InstantHandleAttribute()] System.Func<string> customMessage) { }
+        public static T ShouldHaveSingleItem<T>(this System.Collections.Generic.IEnumerable<T> actual) { }
+        public static T ShouldHaveSingleItem<T>(this System.Collections.Generic.IEnumerable<T> actual, string customMessage) { }
+        public static T ShouldHaveSingleItem<T>(this System.Collections.Generic.IEnumerable<T> actual, [JetBrains.Annotations.InstantHandleAttribute()] System.Func<string> customMessage) { }
         public static void ShouldNotBeEmpty<T>(this System.Collections.Generic.IEnumerable<T> actual) { }
         public static void ShouldNotBeEmpty<T>(this System.Collections.Generic.IEnumerable<T> actual, string customMessage) { }
         public static void ShouldNotBeEmpty<T>(this System.Collections.Generic.IEnumerable<T> actual, [JetBrains.Annotations.InstantHandleAttribute()] System.Func<string> customMessage) { }