Added result extensions for results that contain optional values. (#61)

Author: MrMatthewLayton

OnixLabs.Core.UnitTests/ResultExtensionTests.cs

@@ -0,0 +1,180 @@
+// Copyright 2020 ONIXLabs
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System;
+using Xunit;
+
+namespace OnixLabs.Core.UnitTests;
+
+public sealed class ResultExtensionTests
+{
+    [Fact(DisplayName = "Result.GetValueOrNone should return the Optional value when the result is Success and the Optional value is not None")]
+    public void ResultGetValueOrNoneShouldReturnOptionalValueWhenResultIsSuccessAndOptionalValueIsNotNone()
+    {
+        // Given
+        Optional<int> expectedNumber = 123;
+        Optional<string> expectedText = "abc";
+        Result<Optional<int>> numberResult = expectedNumber;
+        Result<Optional<string>> textResult = expectedText;
+
+        // When
+        Optional<int> actualNumber = numberResult.GetValueOrNone();
+        Optional<string> actualText = textResult.GetValueOrNone();
+
+        // Then
+        Assert.Equal(expectedNumber, actualNumber);
+        Assert.Equal(expectedText, actualText);
+    }
+
+    [Fact(DisplayName = "Result.GetValueOrNone should return None value when the result is Success and the Optional value is None")]
+    public void ResultGetValueOrNoneShouldReturnNoneWhenResultIsSuccessAndOptionalValueIsNotNone()
+    {
+        // Given
+        Optional<int> expectedNumber = Optional<int>.None;
+        Optional<string> expectedText = Optional<string>.None;
+        Result<Optional<int>> numberResult = expectedNumber;
+        Result<Optional<string>> textResult = expectedText;
+
+        // When
+        Optional<int> actualNumber = numberResult.GetValueOrNone();
+        Optional<string> actualText = textResult.GetValueOrNone();
+
+        // Then
+        Assert.Equal(expectedNumber, actualNumber);
+        Assert.Equal(expectedText, actualText);
+    }
+
+    [Fact(DisplayName = "Result.GetValueOrNone should return None value when the result is Failure")]
+    public void ResultGetValueOrNoneShouldReturnNoneWhenResultIsFailure()
+    {
+        // Given
+        Optional<int> expectedNumber = Optional<int>.None;
+        Optional<string> expectedText = Optional<string>.None;
+        Result<Optional<int>> numberResult = Result<Optional<int>>.Failure(new Exception("Result has failed."));
+        Result<Optional<string>> textResult = Result<Optional<string>>.Failure(new Exception("Result has failed."));
+
+        // When
+        Optional<int> actualNumber = numberResult.GetValueOrNone();
+        Optional<string> actualText = textResult.GetValueOrNone();
+
+        // Then
+        Assert.Equal(expectedNumber, actualNumber);
+        Assert.Equal(expectedText, actualText);
+    }
+
+    [Fact(DisplayName = "Result.GetOptionalValueOrThrow should return the Optional value when the Result is Success and the Optional value is not None")]
+    public void ResultGetOptionalValueOrThrowShouldReturnOptionalValueWhenResultIsSuccessAndOptionalValueIsNotNone()
+    {
+        // Given
+        const int expectedNumber = 123;
+        const string expectedText = "abc";
+        Result<Optional<int>> numberResult = Optional<int>.Some(expectedNumber);
+        Result<Optional<string>> textResult = Optional<string>.Some(expectedText);
+
+        // When
+        int actualNumber = numberResult.GetOptionalValueOrThrow();
+        string actualText = textResult.GetOptionalValueOrThrow();
+
+        // Then
+        Assert.Equal(expectedNumber, actualNumber);
+        Assert.Equal(expectedText, actualText);
+    }
+
+    [Fact(DisplayName = "Result.GetOptionalValueOrThrow should throw InvalidOperationException when the Result is Success and the Optional value is None")]
+    public void ResultGetOptionalValueOrThrowShouldThrowInvalidOperationExceptionWhenResultIsSuccessAndOptionalValueIsNone()
+    {
+        // Given
+        Result<Optional<int>> numberResult = Optional<int>.None;
+        Result<Optional<string>> textResult = Optional<string>.None;
+
+        // When
+        Exception numberException = Assert.Throws<InvalidOperationException>(() => numberResult.GetOptionalValueOrThrow());
+        Exception textException = Assert.Throws<InvalidOperationException>(() => textResult.GetOptionalValueOrThrow());
+
+        // Then
+        Assert.Equal("Optional value of type System.Int32 is not present.", numberException.Message);
+        Assert.Equal("Optional value of type System.String is not present.", textException.Message);
+    }
+
+    [Fact(DisplayName = "Result.GetOptionalValueOrThrow should throw InvalidOperationException when the Result is Failure")]
+    public void ResultGetOptionalValueOrThrowShouldThrowInvalidOperationExceptionWhenResultIsFailure()
+    {
+        // Given
+        Result<Optional<int>> numberResult = Result<Optional<int>>.Failure(new Exception("Result has failed."));
+        Result<Optional<string>> textResult = Result<Optional<string>>.Failure(new Exception("Result has failed."));
+
+        // When
+        Exception numberException = Assert.Throws<Exception>(() => numberResult.GetOptionalValueOrThrow());
+        Exception textException = Assert.Throws<Exception>(() => textResult.GetOptionalValueOrThrow());
+
+        // Then
+        Assert.Equal("Result has failed.", numberException.Message);
+        Assert.Equal("Result has failed.", textException.Message);
+    }
+
+
+    [Fact(DisplayName = "Result.GetOptionalValueOrDefault should return the Optional value when the Result is Success and the Optional value is not None")]
+    public void ResultGetOptionalValueOrDefaultShouldReturnOptionalValueWhenResultIsSuccessAndOptionalValueIsNotNone()
+    {
+        // Given
+        const int expectedNumber = 123;
+        const string expectedText = "abc";
+        Result<Optional<int>> numberResult = Optional<int>.Some(expectedNumber);
+        Result<Optional<string>> textResult = Optional<string>.Some(expectedText);
+
+        // When
+        int actualNumber = numberResult.GetOptionalValueOrDefault(456);
+        string actualText = textResult.GetOptionalValueOrDefault("xyz");
+
+        // Then
+        Assert.Equal(expectedNumber, actualNumber);
+        Assert.Equal(expectedText, actualText);
+    }
+
+    [Fact(DisplayName = "Result.GetOptionalValueOrDefault should throw return the default value when the Result is Success and the Optional value is None")]
+    public void ResultGetOptionalValueOrThrowShouldReturnDefaultValueWhenResultIsSuccessAndOptionalValueIsNone()
+    {
+        // Given
+        const int expectedNumber = 456;
+        const string expectedText = "xyz";
+        Result<Optional<int>> numberResult = Optional<int>.None;
+        Result<Optional<string>> textResult = Optional<string>.None;
+
+        // When
+        int actualNumber = numberResult.GetOptionalValueOrDefault(expectedNumber);
+        string actualText = textResult.GetOptionalValueOrDefault(expectedText);
+
+        // Then
+        Assert.Equal(expectedNumber, actualNumber);
+        Assert.Equal(expectedText, actualText);
+    }
+
+    [Fact(DisplayName = "Result.GetOptionalValueOrDefault should return default value when the result is Failure")]
+    public void ResultGetOptionalValueOrDefaultShouldReturnDefaultValueWhenResultIsFailure()
+    {
+        // Given
+        const int expectedNumber = 456;
+        const string expectedText = "xyz";
+        Result<Optional<int>> numberResult = Result<Optional<int>>.Failure(new Exception("Result has failed."));
+        Result<Optional<string>> textResult = Result<Optional<string>>.Failure(new Exception("Result has failed."));
+
+        // When
+        int actualNumber = numberResult.GetOptionalValueOrDefault(expectedNumber);
+        string actualText = textResult.GetOptionalValueOrDefault(expectedText);
+
+        // Then
+        Assert.Equal(expectedNumber, actualNumber);
+        Assert.Equal(expectedText, actualText);
+    }
+}

OnixLabs.Core/Extensions.Result.cs

@@ -0,0 +1,64 @@
+// Copyright 2020 ONIXLabs
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System.ComponentModel;
+
+namespace OnixLabs.Core;
+
+/// <summary>
+/// Provides extension methods for <see cref="Result{T}"/> instances.
+/// </summary>
+[EditorBrowsable(EditorBrowsableState.Never)]
+public static class ResultExtensions
+{
+    /// <summary>
+    /// Gets the <see cref="Optional{T}"/> value of the current <see cref="Result{T}"/> instance,
+    /// or <see cref="Optional{T}.None"/> if the result is in a <see cref="Failure{T}"/> state.
+    /// </summary>
+    /// <param name="result">The <see cref="Result{T}"/> instance from which to obtain the <see cref="Optional{T}"/> value.</param>
+    /// <typeparam name="T">The underlying type of the <see cref="Optional{T}"/> value.</typeparam>
+    /// <returns>
+    /// Return the <see cref="Optional{T}"/> value of the current <see cref="Result{T}"/> instance,
+    /// or <see cref="Optional{T}.None"/> if the result is in a <see cref="Failure{T}"/> state.
+    /// </returns>
+    public static Optional<T> GetValueOrNone<T>(this Result<Optional<T>> result) where T : notnull =>
+        result is Success<Optional<T>> { Value.HasValue: true } ? result.GetValueOrThrow() : Optional<T>.None;
+
+    /// <summary>
+    /// Gets the underlying <typeparamref name="T"/> value from the current <see cref="Result{T}"/> of <see cref="Optional{T}"/>,
+    /// or throws an exception if the result is in a <see cref="Failure{T}"/> state, or the <see cref="Optional{T}"/> is <see cref="Optional{T}.None"/>.
+    /// </summary>
+    /// <param name="result">The <see cref="Result{T}"/> instance from which to obtain the <see cref="Optional{T}"/> value.</param>
+    /// <typeparam name="T">The underlying type of the <see cref="Optional{T}"/> value.</typeparam>
+    /// <returns>
+    /// Returns the underlying <typeparamref name="T"/> value from the current <see cref="Result{T}"/> of <see cref="Optional{T}"/>,
+    /// or throws an exception if the result is in a <see cref="Failure{T}"/> state, or the <see cref="Optional{T}"/> is <see cref="Optional{T}.None"/>.
+    /// </returns>
+    public static T GetOptionalValueOrThrow<T>(this Result<Optional<T>> result) where T : notnull =>
+        result.GetValueOrThrow().GetValueOrThrow();
+
+    /// <summary>
+    /// Gets the underlying <typeparamref name="T"/> value from the current <see cref="Result{T}"/> of <see cref="Optional{T}"/>,
+    /// or returns the default value if the result is in a <see cref="Failure{T}"/> state, or the <see cref="Optional{T}"/> is <see cref="Optional{T}.None"/>.
+    /// </summary>
+    /// <param name="result">The <see cref="Result{T}"/> instance from which to obtain the <see cref="Optional{T}"/> value.</param>
+    /// <param name="defaultValue">The default value to return if the result is in a <see cref="Failure{T}"/> state, or the <see cref="Optional{T}"/> is <see cref="Optional{T}.None"/>.</param>
+    /// <typeparam name="T">The underlying type of the <see cref="Optional{T}"/> value.</typeparam>
+    /// <returns>
+    /// Returns the underlying <typeparamref name="T"/> value from the current <see cref="Result{T}"/> of <see cref="Optional{T}"/>,
+    /// or returns the default value if the result is in a <see cref="Failure{T}"/> state, or the <see cref="Optional{T}"/> is <see cref="Optional{T}.None"/>.
+    /// </returns>
+    public static T GetOptionalValueOrDefault<T>(this Result<Optional<T>> result, T defaultValue) where T : notnull =>
+        result is Success<Optional<T>> { Value.HasValue: true } ? result.GetOptionalValueOrThrow() : defaultValue;
+}