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Set 🔥 to your old tests! A better way to write tests in C#.

Why?

Most tests in C# are written in an arrange, act, assert style, like so,


[Fact(DisplayName = "SerializeAsync can work with anonymous objects")]
public async Task ExampleTest()
{
    // Arrange
    var widget = new { Name = "Widget1", Cost = 12.50 };
    var ms = new MemoryStream();

    // Act
    await JsonSerializer.SerializeAsync(ms, widget);

    // Assert
    Assert.Equal(
        expected: "{\"Name\":\"Widget1\",\"Cost\":12.5}",
        actual: Encoding.UTF8.GetString(ms.ToArray())
    );
}

This structure is only a convention and is not enforced by the test framework.

This library aims to formalize this structure in the following ways,

Enforces that all tests must be arranged before acting and acted upon before assertions can occur. Making it a compile-time error if this is not followed
Scaffolding tests using a fluent API making them easier to read, write and refactor
Encourages automatic refactoring of tests sections into helper methods, which is only possible if the test is structured using delegates
Works with the developers IDE to provide a better experience when writing tests


[Fact(DisplayName = "SerializeAsync can work with anonymous objects")]
public Task ExampleTestUsingAaaBuilder2() =>
    Arrange(() =>
        {
            var widget = new { Name = "Widget1", Cost = 12.50 };
            var ms = new MemoryStream();
            return (widget, ms);
        })
        // pull out the shared test code
        .Act(CallSerializeAsync)
        .Assert(result =>
            Assert.Equal(expected: "{\"Name\":\"Widget1\",\"Cost\":12.5}", actual: result)
        );

// this is now a shared stage and can be used in many tests
private static async Task<string> CallSerializeAsync<T>((T, MemoryStream) data)
{
    var (widget, ms) = data;
    await JsonSerializer.SerializeAsync(ms, widget);
    return Encoding.UTF8.GetString(ms.ToArray());
}

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