view rust/hg-core/src/copy_tracing/tests.rs @ 50979:4c5f6e95df84

rust: make `Revision` a newtype

This change is the one we've been building towards during this series.
The aim is to make `Revision` mean more than a simple integer, holding
the information that it is valid for a given revlog index.
While this still allows for programmer error, since creating a revision
directly and querying a different index with a "checked" revision are
still possible, the friction created by the newtype will hopefully make
us think twice about which type to use.

Enough of the Rust ecosystem relies on the newtype pattern to be
efficiently optimized away (even compiler in codegen tests¹), so I'm not
worried about this being a fundamental problem.

[1] https://github.com/rust-lang/rust/blob/7a70647f195f6b0a0f1ebd72b1542ba91a32f43a/tests/codegen/vec-in-place.rs#L47

use super::*;

/// Shorthand to reduce boilerplate when creating [`Revision`] for testing
macro_rules! R {
    ($revision:literal) => {
        Revision($revision)
    };
}

/// Unit tests for:
///
/// ```ignore
/// fn compare_value(
///     current_merge: Revision,
///     merge_case_for_dest: impl Fn() -> MergeCase,
///     src_minor: &CopySource,
///     src_major: &CopySource,
/// ) -> (MergePick, /* overwrite: */ bool)
///  ```
#[test]
fn test_compare_value() {
    // The `compare_value!` macro calls the `compare_value` function with
    // arguments given in pseudo-syntax:
    //
    // * For `merge_case_for_dest` it takes a plain `MergeCase` value instead
    //   of a closure.
    // * `CopySource` values are represented as `(rev, path, overwritten)`
    //   tuples of type `(Revision, Option<PathToken>, OrdSet<Revision>)`.
    // * `PathToken` is an integer not read by `compare_value`. It only checks
    //   for `Some(_)` indicating a file copy v.s. `None` for a file deletion.
    // * `OrdSet<Revision>` is represented as a Python-like set literal.

    use MergeCase::*;
    use MergePick::*;

    assert_eq!(
        compare_value!(
            R!(1),
            Normal,
            (R!(1), None, { R!(1) }),
            (R!(1), None, { R!(1) })
        ),
        (Any, false)
    );
}

/// Unit tests for:
///
/// ```ignore
/// fn merge_copies_dict(
///     path_map: &TwoWayPathMap, // Not visible in test cases
///     current_merge: Revision,
///     minor: InternalPathCopies,
///     major: InternalPathCopies,
///     get_merge_case: impl Fn(&HgPath) -> MergeCase + Copy,
/// ) -> InternalPathCopies
/// ```
#[test]
fn test_merge_copies_dict() {
    // The `merge_copies_dict!` macro calls the `merge_copies_dict` function
    // with arguments given in pseudo-syntax:
    //
    // * `TwoWayPathMap` and path tokenization are implicitly taken care of.
    //   All paths are given as string literals.
    // * Key-value maps are represented with `{key1 => value1, key2 => value2}`
    //   pseudo-syntax.
    // * `InternalPathCopies` is a map of copy destination path keys to
    //   `CopySource` values.
    //   - `CopySource` is represented as a `(rev, source_path, overwritten)`
    //     tuple of type `(Revision, Option<Path>, OrdSet<Revision>)`.
    //   - Unlike in `test_compare_value`, source paths are string literals.
    //   - `OrdSet<Revision>` is again represented as a Python-like set
    //     literal.
    // * `get_merge_case` is represented as a map of copy destination path to
    //   `MergeCase`. The default for paths not in the map is
    //   `MergeCase::Normal`.
    //
    // `internal_path_copies!` creates an `InternalPathCopies` value with the
    // same pseudo-syntax as in `merge_copies_dict!`.

    use MergeCase::*;

    assert_eq!(
        merge_copies_dict!(
            R!(1),
            {"foo" => (R!(1), None, {})},
            {},
            {"foo" => Merged}
        ),
        internal_path_copies!("foo" => (R!(1), None, {}))
    );
}

/// Unit tests for:
///
/// ```ignore
/// impl CombineChangesetCopies {
///     fn new(children_count: HashMap<Revision, usize>) -> Self
///
///     // Called repeatedly:
///     fn add_revision_inner<'a>(
///         &mut self,
///         rev: Revision,
///         p1: Revision,
///         p2: Revision,
///         copy_actions: impl Iterator<Item = Action<'a>>,
///         get_merge_case: impl Fn(&HgPath) -> MergeCase + Copy,
///     )
///
///     fn finish(mut self, target_rev: Revision) -> PathCopies
/// }
/// ```
#[test]
fn test_combine_changeset_copies() {
    // `combine_changeset_copies!` creates a `CombineChangesetCopies` with
    // `new`, then calls `add_revision_inner` repeatedly, then calls `finish`
    // for its return value.
    //
    // All paths given as string literals.
    //
    // * Key-value maps are represented with `{key1 => value1, key2 => value2}`
    //   pseudo-syntax.
    // * `children_count` is a map of revision numbers to count of children in
    //   the DAG. It includes all revisions that should be considered by the
    //   algorithm.
    // * Calls to `add_revision_inner` are represented as an array of anonymous
    //   structs with named fields, one pseudo-struct per call.
    //
    // `path_copies!` creates a `PathCopies` value, a map of copy destination
    // keys to copy source values. Note: the arrows for map literal syntax
    // point **backwards** compared to the logical direction of copy!

    use crate::revlog::NULL_REVISION as NULL;
    use Action::*;
    use MergeCase::*;

    assert_eq!(
        combine_changeset_copies!(
            { R!(1) => 1, R!(2) => 1 },
            [
                {
                    rev: R!(1),
                    p1: NULL,
                    p2: NULL,
                    actions: [],
                    merge_cases: {},
                },
                {
                    rev: R!(2),
                    p1: NULL,
                    p2: NULL,
                    actions: [],
                    merge_cases: {},
                },
                {
                    rev: R!(3), p1: R!(1), p2: R!(2),
                    actions: [CopiedFromP1("destination.txt", "source.txt")],
                    merge_cases: {"destination.txt" => Merged},
                },
            ],
            R!(3),
        ),
        path_copies!("destination.txt" => "source.txt")
    );
}