Attribute Macro property_test 

#[property_test]

Available on crate feature attr-macro only.

The property_test procedural macro simplifies the creation of property-based tests using the proptest crate. This macro provides a more concise syntax for writing tests that automatically generate test cases based on properties.

Example

Using the property_test macro:

#[property_test]
fn foo(x: i32) {
    assert_eq!(x, x);
}

is roughly equivalent to:

proptest! {
    #[test]
    fn foo(x in any::<i32>()) {
        assert_eq!(x, x);
    }
}

Details

The property_test macro is used to define property-based tests, where the parameters of the test function are automatically generated by proptest. The macro takes care of setting up the test harness and generating input values, allowing the user to focus on writing the test logic.

Attributes

The property_test macro can take an optional config attribute, which allows you to customize the configuration of the proptest runner.

E.g. running 100 cases:

#[property_test(config = "ProptestConfig { cases: 100, .. ProptestConfig::default() }")]
fn foo(x: i32) {
    assert_eq!(x, x);
}

Custom strategies

By default, [property_test] will use the Arbitrary impl for parameters. However, you can provide a custom Strategy with #[strategy = <expr>] on an argument:

#[property_test]
fn foo(#[strategy = "[0-9]*"] s: String) {
    for c in s.chars() {
        assert!(c.is_numeric());
    }
}

Multiple #[strategy = <expr>] attributes on an argument are not allowed.

Semver guarantees of generated code

This macro generates a struct with a name derived from the name of the test function. Details of this struct, such as its name, field names, or even whether it exists are considered implementation details, and may change without a major version bump.