Expect Tests

Based on https://github.com/rust-analyzer/expect-test Explanation: https://blog.janestreet.com/the-joy-of-expect-tests/

Basic Usage:

expect!(fibonacci(15), "610");

The macro will use the Debug trait representation (except for string literals) and compare it to the string literal.

If there is a mismatch such as expect!(fibonacci(15), "987");, an error with the diff will be shown:

`` You can update allexpect!tests by running: UPDATE_EXPECT=1 cargo test To update a single test, place the cursor onexpecttoken and userun` feature of rust-analyzer.

Expect:

987

Actual:

610

Diff:

987610

```

If UPDATE_EXPECT environment variable is set, the macro will directly update the source file to fix it. Here's an example:

expect!(fibonacci(15));

After running UPDATE_EXPECT=1 cargo test, your source file should automatically be updated to

expect!(fibonacci(15), "610");

Multiple expects:

Maybe you want to test a callback, but for some reason (maybe due to laziness) it is too cumbersome to collect it into a vec before expect!ing it. We can do something like this:

``` fn somecomplicatedio_func(callback: impl Fn(i32)) { callback(5); callback(3); callback(10); }

somecomplicatediofunc(|statusvalue| { expect!(status_value, "5", "3", "10"); })

```

Caveat: expect-tests cannot detect when the expect! macro is never called. Therefore, something like

for i in 0..2 { expect!(i, "0", "1", "2", "3", "4"); }

will pass even though "2", "3", and "4" are never run.

Examples (that are used to test this crate!): https://github.com/awesomelemonade/expect-tests/blob/master/src/tests.rs

Alternatives:

expect-test: https://docs.rs/expect-test/latest/expect_test/ insta: https://crates.io/crates/insta k9: https://crates.io/crates/k9

Other notes: - Does a "best effort" to comply with rustfmt. When the macro detects a multiline expect, updating will attempt to insert newlines where appropriate - Indentations are ignored in the string literals when comparing. This is so it is prettier in the code.