Testing Your Implementation

By enabling the impl-tester feature, you gain access to machinery that makes it easy to test your custom Diffable and Patchable implementations.

The DipaImplTester will.

1. Delta encode your provided start and end values.

2. Serialize the delta using bincode with variable integer encoding.

3. Assert that the number of bytes is what you expect.

4. Deserialize the delta back to DeltaOwned.

5. Apply the delta to your original start value.

6. Ensure that your start value now equals your end value.

# Cargo.toml

[dev-dependencies]
dipa = {version = "0.1", features = ["impl-tester"]}

#![allow(unused_variables)]
fn main() {
use dipa::CreateDeltaTowardsReturn;

struct MyStruct {
    field: u8
}

enum MyDelta<'a> {
   New(&'a u8)
}

enum MyDeltaOwned {
   New(u8)
}

impl<'s,'e> Diffable<'s, 'e, MyStruct> for MyStruct {
    type Delta = MyDelta;
    type DeltaOwned = MyDeltaOwned;

    fn create_delta_towards (&self, &end_state) -> CreateDeltaTowardsReturn<Self::Delta> {
        todo!()
    }
}

type MyStructPatch<'s, 'e> = <MyStruct as Diffable<'s, 'e, MyStruct>;
impl<'s, 'e> Patchable<MyStructPatch<'s, 'e'>> for MyStruct {
    fn apply_patch (&mut self, patch: MyStructPatch<'s, 'e>) {
        todo!()
    }
}

#[cfg(test)]
mod tests {
    use dipa::DipaImplTester;

    #[test]
    fn diff_my_struct_changed() {
        DipaImplTester {
            label: Some("Diff MyStruct changed"),
            start: &mut MyStruct { field: 2 },
            end: &MyStruct { field: 5 },
            expected_delta: MyDelta::New(&5),
            expected_serialized_patch_size: 2,
            expected_did_change: true
        }
        .test();
    }

    #[test]
    fn diff_my_struct_no_change() {
        DipaImplTester {
            label: Some("Diff MyStruct no change"),
            start: &mut MyStruct { field: 2 },
            end: &MyStruct { field: 2 },
            expected_delta: MyDelta::New(&2),
            expected_serialized_patch_size: 2,
            expected_did_change: false
        }
        .test();
    }
}
}