beady

A macro for writing tests in a Behaviour Driven (BD) style. Inspired by Catch2.

• Simple (doesn't really do anything except rearrange your tests)
• Provides helpful output for when tests fail
• Works with tokio::test (and other custom test attributes)

Example

```rust use beady::scenario;

[scenario]

fn pushinganelementtoavec() { #[given(anempty_vec)] { let mut vec = vec![];

    #[when(an_element_is_pushed_to_the_vec)] {
        vec.push(7);

        #[then(the_vec_should_have_one_element)] {
            assert_eq!(vec.len(), 1);

            #[and_then(that_element_should_be_the_pushed_value)] {
                assert_eq!(vec[0], 7);
            }
        }

        #[and_when(the_vec_is_cleared)] {
            vec.clear();

            #[then(the_vec_should_be_empty)] {
                assert!(vec.is_empty());
            }
        }
    }
}

} ```

Running cargo test we can see that this scenario has generated three tests:

```shell running 3 tests test pushinganelementtoavec::given::anemptyvec::when::anelementispushedtothevec::then::thevecshouldhaveoneelement::and::theelementshouldbethepushedvalue ... ok test pushinganelementtoavec::given::anemptyvec::when::anelementispushedtothevec::and::theveciscleared::then::thevecshouldbeempty ... ok test pushinganelementtoavec::given::anemptyvec::when::anelementispushedtothevec::then::thevecshouldhaveoneelement ... ok

test result: ok. 3 passed; 0 failed; 0 ignored; 0 measured; 3 filtered out; finished in 0.00s ```

And if we make one of our asserts intentionally fail then we see a full description of the failing scenario alongside the panic message:

```shell test pushinganelementtoavec::given::anemptyvec::when::anelementispushedtothevec::then::thevecshouldhaveoneelement::and::theelementshouldbethepushedvalue ... FAILED

failures:

---- pushinganelementtoavec::given::anemptyvec::when::anelementispushedtothevec::then::thevecshouldhaveoneelement::and::theelementshouldbethepushedvalue stdout ----

Scenario: pushing an element to a vec Given: an empty vec When: an element is pushed to the vec Then: the vec should have one element and: the element should be the pushed value

thread 'pushinganelementtoavec::given::anemptyvec::when::anelementispushedtothevec::then::thevecshouldhaveoneelement::and::theelementshouldbethepushedvalue' panicked at 'assertion failed: (left == right) left: 7, right: 8' ```

Usage

Inspired by the BDD-style test cases from Catch2, you can annotate a function with #[scenario] to make it a test, and then use the #[given], #[when], and #[then] attributes to describe the test. Dependent clauses can be specified with the #[and_given], #[and_when], and #[and_then] attributes.

#[scenario]

By default the #[scenario] attribute will generate tests like:

```rust

[test]

fn foo() { ... } ```

If you want to use another test attribute you can specify it after the #[scenario] attribute like so:

```rust

[scenario]

[tokio::test]

async fn my_scenario() { ... } ```

Which will generate tests like:

```rust

[tokio::test]

async fn foo() { ... } ```