/
AsyncFunctionAssertions.cs
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/
AsyncFunctionAssertions.cs
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using System;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using FluentAssertions.Execution;
namespace FluentAssertions.Specialized
{
/// <summary>
/// Contains a number of methods to assert that an asynchronous method yields the expected result.
/// </summary>
[DebuggerNonUserCode]
public class AsyncFunctionAssertions
{
private readonly IExtractExceptions extractor;
public AsyncFunctionAssertions(Func<Task> subject, IExtractExceptions extractor)
{
this.extractor = extractor;
Subject = subject;
}
/// <summary>
/// Gets the <see cref="Func{Task}"/> that is being asserted.
/// </summary>
public Func<Task> Subject { get; private set; }
/// <summary>
/// Asserts that the current <see cref="Func{Task}"/> throws an exception of type <typeparamref name="TException"/>.
/// </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 <see cref="because" />.
/// </param>
public ExceptionAssertions<TException> Throw<TException>(string because = "", params object[] becauseArgs)
where TException : Exception
{
Exception exception = InvokeSubjectWithInterception();
return Throw<TException>(exception, because, becauseArgs);
}
/// <summary>
/// Asserts that the current <see cref="Func{Task}"/> throws an exception of type <typeparamref name="TException"/>.
/// </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 <see cref="because" />.
/// </param>
public async Task<ExceptionAssertions<TException>> ThrowAsync<TException>(string because = "", params object[] becauseArgs)
where TException : Exception
{
Exception exception = await InvokeSubjectWithInterceptionAsync();
return Throw<TException>(exception, because, becauseArgs);
}
/// <summary>
/// Asserts that the current <see cref="Func{Task}"/> does not throw any exception.
/// </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 <see cref="because" />.
/// </param>
public void NotThrow(string because = "", params object[] becauseArgs)
{
try
{
Task.Run(Subject).Wait();
}
catch (Exception exception)
{
NotThrow(exception, because, becauseArgs);
}
}
/// <summary>
/// Asserts that the current <see cref="Func{Task}"/> does not throw any exception.
/// </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 <see cref="because" />.
/// </param>
public async Task NotThrowAsync(string because = "", params object[] becauseArgs)
{
try
{
await Task.Run(Subject);
}
catch (Exception exception)
{
NotThrow(exception, because, becauseArgs);
}
}
/// <summary>
/// Asserts that the current <see cref="Func{Task}"/> does not throw an exception of type <typeparamref name="TException"/>.
/// </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 <see cref="because" />.
/// </param>
public void NotThrow<TException>(string because = "", params object[] becauseArgs)
where TException : Exception
{
try
{
Task.Run(Subject).Wait();
}
catch (Exception exception)
{
NotThrow<TException>(exception, because, becauseArgs);
}
}
/// <summary>
/// Asserts that the current <see cref="Func{Task}"/> does not throw an exception of type <typeparamref name="TException"/>.
/// </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 <see cref="because" />.
/// </param>
public async Task NotThrowAsync<TException>(string because = "", params object[] becauseArgs)
where TException : Exception
{
try
{
await Task.Run(Subject);
}
catch (Exception exception)
{
NotThrow<TException>(exception, because, becauseArgs);
}
}
private static void NotThrow(Exception exception, string because, object[] becauseArgs)
{
Exception nonAggregateException = GetFirstNonAggregateException(exception);
Execute.Assertion
.BecauseOf(because, becauseArgs)
.FailWith("Did not expect any exception{reason}, but found a {0} with message {1}.",
nonAggregateException.GetType(), nonAggregateException.ToString());
}
private static void NotThrow<TException>(Exception exception, string because, object[] becauseArgs) where TException : Exception
{
Exception nonAggregateException = GetFirstNonAggregateException(exception);
if (nonAggregateException != null)
{
Execute.Assertion
.ForCondition(!(nonAggregateException is TException))
.BecauseOf(because, becauseArgs)
.FailWith("Did not expect {0}{reason}, but found one with message {1}.",
typeof(TException), nonAggregateException.ToString());
}
}
/// <summary>
/// Asserts that the current <see cref="Func{T}"/> stops throwing any exception
/// after a specified amount of time.
/// </summary>
/// <remarks>
/// The <see cref="Func{T}"/> is invoked. If it raises an exception,
/// the invocation is repeated until it either stops raising any exceptions
/// or the specified wait time is exceeded.
/// </remarks>
/// <param name="waitTime">
/// The time after which the <see cref="Func{T}"/> should have stopped throwing any exception.
/// </param>
/// <param name="pollInterval">
/// The time between subsequent invocations of the <see cref="Func{T}"/>.
/// </param>
/// <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 <see cref="because" />.
/// </param>
/// <exception cref="ArgumentOutOfRangeException">Throws if waitTime or pollInterval are negative.</exception>
public void NotThrowAfter(TimeSpan waitTime, TimeSpan pollInterval, string because = "", params object[] becauseArgs)
{
if (waitTime < TimeSpan.Zero)
{
throw new ArgumentOutOfRangeException(nameof(waitTime), $"The value of {nameof(waitTime)} must be non-negative.");
}
if (pollInterval < TimeSpan.Zero)
{
throw new ArgumentOutOfRangeException(nameof(pollInterval), $"The value of {nameof(pollInterval)} must be non-negative.");
}
TimeSpan? invocationEndTime = null;
Exception exception = null;
var watch = Stopwatch.StartNew();
while (invocationEndTime is null || invocationEndTime < waitTime)
{
exception = InvokeSubjectWithInterception();
if (exception is null)
{
return;
}
Task.Delay(pollInterval).Wait();
invocationEndTime = watch.Elapsed;
}
Execute.Assertion
.BecauseOf(because, becauseArgs)
.FailWith("Did not expect any exceptions after {0}{reason}, but found {1}.", waitTime, exception);
}
/// <summary>
/// Asserts that the current <see cref="Func{T}"/> stops throwing any exception
/// after a specified amount of time.
/// </summary>
/// <remarks>
/// The <see cref="Func{T}"/> is invoked. If it raises an exception,
/// the invocation is repeated until it either stops raising any exceptions
/// or the specified wait time is exceeded.
/// </remarks>
/// <param name="waitTime">
/// The time after which the <see cref="Func{T}"/> should have stopped throwing any exception.
/// </param>
/// <param name="pollInterval">
/// The time between subsequent invocations of the <see cref="Func{T}"/>.
/// </param>
/// <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 <see cref="because" />.
/// </param>
/// <exception cref="ArgumentOutOfRangeException">Throws if waitTime or pollInterval are negative.</exception>
public async Task NotThrowAfterAsync(TimeSpan waitTime, TimeSpan pollInterval, string because = "", params object[] becauseArgs)
{
if (waitTime < TimeSpan.Zero)
{
throw new ArgumentOutOfRangeException(nameof(waitTime), $"The value of {nameof(waitTime)} must be non-negative.");
}
if (pollInterval < TimeSpan.Zero)
{
throw new ArgumentOutOfRangeException(nameof(pollInterval), $"The value of {nameof(pollInterval)} must be non-negative.");
}
TimeSpan? invocationEndTime = null;
Exception exception = null;
var watch = Stopwatch.StartNew();
while (invocationEndTime is null || invocationEndTime < waitTime)
{
exception = await InvokeSubjectWithInterceptionAsync();
if (exception is null)
{
return;
}
await Task.Delay(pollInterval);
invocationEndTime = watch.Elapsed;
}
Execute.Assertion
.BecauseOf(because, becauseArgs)
.FailWith("Did not expect any exceptions after {0}{reason}, but found {1}.", waitTime, exception);
}
private static Exception GetFirstNonAggregateException(Exception exception)
{
Exception nonAggregateException = exception;
while (nonAggregateException is AggregateException)
{
nonAggregateException = nonAggregateException.InnerException;
}
return nonAggregateException;
}
private ExceptionAssertions<TException> Throw<TException>(Exception exception, string because, object[] becauseArgs)
where TException : Exception
{
var exceptions = extractor.OfType<TException>(exception);
Execute.Assertion
.ForCondition(exception != null)
.BecauseOf(because, becauseArgs)
.FailWith("Expected {0}{reason}, but no exception was thrown.", typeof(TException));
Execute.Assertion
.ForCondition(exceptions.Any())
.BecauseOf(because, becauseArgs)
.FailWith("Expected {0}{reason}, but found {1}.", typeof(TException), exception);
return new ExceptionAssertions<TException>(exceptions);
}
private Exception InvokeSubjectWithInterception()
{
try
{
Task.Run(Subject).Wait();
}
catch (Exception exception)
{
return InterceptException(exception);
}
return null;
}
private async Task<Exception> InvokeSubjectWithInterceptionAsync()
{
try
{
await Task.Run(Subject);
}
catch (Exception exception)
{
return InterceptException(exception);
}
return null;
}
private Exception InterceptException(Exception exception)
{
var ar = exception as AggregateException;
if (ar?.InnerException is AggregateException)
{
return ar.InnerException;
}
return exception;
}
}
}