Refactor generators tests and add missing tests

src/generators.rs

@@ -3,34 +3,39 @@
 use crate::models::AppendGraph;
 use crate::traits::{GraphTopology, GraphTopologyAddition, GraphTopologyConversion};
 
-/// Builds a graph of type `G` by running a generator on a temporary [`AppendGraph`].
+/// Builds a graph of type `G` by running a generator on a temporary graph.
 ///
-/// `generate_as` fills a temporary graph and converts it to `G`. It returns the handles of the
-/// elements it created as handles of the resulting graph. This makes it possible to obtain graph
-/// types directly that do not implement [`GraphTopologyAddition`], such as [`FrozenGraph`].
+/// `generate_as` fills a temporary [`AppendGraph`] and converts it to `G`. It returns the handles
+/// of the elements it created as handles of the resulting graph. This makes it possible to obtain
+/// graph types directly that do not implement [`GraphTopologyAddition`], such as [`FrozenGraph`].
 ///
 /// # Examples
 ///
 /// ```
+/// use grapherity::prelude::*;
 /// use grapherity::generators;
 /// use grapherity::models::FrozenGraph;
-/// use grapherity::traits::GraphTopology;
 ///
-/// let (graph, vertices, edges) = generators::generate_as::<FrozenGraph, _, _>(generators::petersen);
+/// // Generates a parameterless Petersen graph as a FrozenGraph model.
+/// let (graph, vertices, edges) = generators::generate_as::<FrozenGraph>(generators::petersen);
 /// assert_eq!(graph.vertex_count(), 10);
-/// assert_eq!(graph.edge_count(), 15);
 /// assert!(graph.vertices().all(|v| graph.degree(v) == 3));
+///
+/// // Generates a parameterized complete graph as a FrozenGraph model.
+/// let (graph, vertices, edges) = generators::generate_as::<FrozenGraph>(|g| generators::complete(g, 5));
+/// assert_eq!(graph.vertex_count(), 5);
+/// assert!(graph.vertices().all(|v| graph.degree(v) == 4));
 /// ```
 ///
 /// [`FrozenGraph`]: crate::models::FrozenGraph
-pub fn generate_as<G, const V: usize, const E: usize>(
+pub fn generate_as<G>(
     generator: impl FnOnce(
         &mut AppendGraph,
     ) -> (
-        [<AppendGraph as GraphTopology>::Vertex; V],
-        [<AppendGraph as GraphTopology>::Edge; E],
+        Vec<<AppendGraph as GraphTopology>::Vertex>,
+        Vec<<AppendGraph as GraphTopology>::Edge>,
     ),
-) -> (G, [G::Vertex; V], [G::Edge; E])
+) -> (G, Vec<G::Vertex>, Vec<G::Edge>)
 where
     G: GraphTopologyConversion,
 {
@@ -39,33 +44,92 @@ where
     let (graph, iso) = G::convert(&builder);
     (
         graph,
-        vertices.map(|v| iso.vertex(v)),
-        edges.map(|e| iso.edge(e)),
+        vertices.into_iter().map(|v| iso.vertex(v)).collect(),
+        edges.into_iter().map(|e| iso.edge(e)).collect(),
     )
 }
 
+/// Generates a path graph.
+///
+/// Generates a [path graph] *P(n)* with `n` vertices and `n - 1` edges in `graph` as a new
+/// connected component and returns the new vertices *v0, v1, ..., v(n - 1)* and edges
+/// *e0, e1, ..., e(n - 2)* in order, i.e. *e0 = (v0, v1)*, *e1 = (v1, v2)*, etc. and *v0* and
+/// *v(n-1)* being the two terminal vertices
+///
+/// For `n == 0`, nothing is added. For `n == 1`, only a single vertex and no edges are added.
+///
+/// [Path graph]: https://en.wikipedia.org/wiki/Path_graph
+pub fn path<G: GraphTopologyAddition>(graph: &mut G, n: usize) -> (Vec<G::Vertex>, Vec<G::Edge>) {
+    let edge_capacity = n.saturating_sub(1);
+    graph.reserve_vertices(n);
+    graph.reserve_edges(edge_capacity);
+    let vertices: Vec<_> = (0..n).map(|_| graph.add_vertex()).collect();
+    let edges = (0..edge_capacity)
+        .map(|i| graph.add_edge(vertices[i], vertices[i + 1]))
+        .collect();
+    (vertices, edges)
+}
+
+/// Generates a cycle graph.
+///
+/// Generates a [cycle graph] *C(n)* with `n` vertices and `n` edges in `graph` as a new connected
+/// component and returns the new vertices *v0, v1, ..., v(n - 1)* and edges *e0, e1, ..., e(n - 1)*
+/// in order, i.e. *e0 = (v0, v1), e1 = (v1, v2), ..., e(n - 1) = (v(n - 1), v0)*.
+///
+/// For `n == 0`, nothing is added. For `n == 1`, a single vertex with a loop is added. For
+/// `n == 2`, two vertices and two edges between them (multi-edge) are added.
+///
+/// [Cycle graph]: https://en.wikipedia.org/wiki/Cycle_graph
+pub fn cycle<G: GraphTopologyAddition>(graph: &mut G, n: usize) -> (Vec<G::Vertex>, Vec<G::Edge>) {
+    graph.reserve_vertices(n);
+    graph.reserve_edges(n);
+    let vertices: Vec<_> = (0..n).map(|_| graph.add_vertex()).collect();
+    let edges = (0..n)
+        .map(|i| graph.add_edge(vertices[i], vertices[if i < n - 1 { i + 1 } else { 0 }]))
+        .collect();
+    (vertices, edges)
+}
+
+/// Generates a complete graph.
+///
+/// Generates a [complete graph] *K(n)* with `n` vertices and `n * (n - 1) / 2` edges in `graph` as
+/// a new connected component and returns the new vertices and edges.
+///
+/// For `n == 0`, nothing is added. For `n == 1`, only a single vertex is added.
+///
+/// [Complete graph]: https://en.wikipedia.org/wiki/Complete_graph
+pub fn complete<G: GraphTopologyAddition>(
+    graph: &mut G,
+    n: usize,
+) -> (Vec<G::Vertex>, Vec<G::Edge>) {
+    let edge_capacity = n * n.saturating_sub(1) / 2;
+    graph.reserve_vertices(n);
+    graph.reserve_edges(edge_capacity);
+    let vertices: Vec<_> = (0..n).map(|_| graph.add_vertex()).collect();
+    let mut edges = Vec::with_capacity(edge_capacity);
+    for (i, &u) in vertices.iter().enumerate() {
+        for &v in &vertices[i + 1..] {
+            edges.push(graph.add_edge(u, v));
+        }
+    }
+    (vertices, edges)
+}
+
 /// Generates a Petersen graph.
 ///
 /// Generates a [Petersen graph] in `graph` as a new connected component and returns the new
 /// vertices and edges. This graph is also the Kneser graph *KG(5, 2)*.
 ///
 /// [Petersen graph]: https://en.wikipedia.org/wiki/Petersen_graph
-pub fn petersen<G>(
-    graph: &mut G,
-) -> (
-    [<G as GraphTopology>::Vertex; 10],
-    [<G as GraphTopology>::Edge; 15],
-)
-where
-    G: GraphTopologyAddition,
-{
+pub fn petersen<G: GraphTopologyAddition>(graph: &mut G) -> (Vec<G::Vertex>, Vec<G::Edge>) {
     const N: usize = 5;
     const K: usize = 2;
 
     graph.reserve_vertices(10);
     graph.reserve_edges(15);
-    let vertices = core::array::from_fn(|_| graph.add_vertex());
-    let edges = core::array::from_fn(|j| {
+    let vertices: Vec<_> = (0..10).map(|_| graph.add_vertex()).collect();
+    let edges = (0..15)
+        .map(|j| {
             let i = j / 3;
             match j % 3 {
                 0 => {
@@ -78,7 +142,8 @@ where
                 }
                 _ => graph.add_edge(vertices[i], vertices[i + N]),
             }
-    });
+        })
+        .collect();
     (vertices, edges)
 }
 
@@ -87,67 +152,342 @@ mod tests {
     use std::fmt::Debug;
 
     use super::*;
-    use crate::models::{FrozenGraph, Graph};
+    use crate::testing::fixtures::MakeTestGraph;
 
-    #[test]
-    fn petersen_append_graph() {
-        petersen_add::<AppendGraph>();
+    #[derive(Debug, Clone, Copy)]
+    enum Spec {
+        Path(usize),
+        Cycle(usize),
+        Complete(usize),
+        Petersen,
     }
 
-    #[test]
-    fn petersen_graph() {
-        petersen_add::<Graph>();
+    impl Spec {
+        fn generate<G: GraphTopologyAddition>(
+            &self,
+            graph: &mut G,
+        ) -> (Vec<G::Vertex>, Vec<G::Edge>) {
+            match *self {
+                Spec::Path(n) => path(graph, n),
+                Spec::Cycle(n) => cycle(graph, n),
+                Spec::Complete(n) => complete(graph, n),
+                Spec::Petersen => petersen(graph),
+            }
         }
 
-    #[test]
-    fn petersen_frozen_graph() {
-        petersen_generate_as::<FrozenGraph>();
-    }
-
-    fn petersen_generate_as<G: GraphTopologyConversion>()
+        fn assert<G: GraphTopology>(&self, built: &Built<G>)
         where
             G::Vertex: Debug,
             G::Edge: Debug,
         {
-        let (graph, vertices, edges) = generate_as::<G, _, _>(petersen);
-        assert_petersen(&graph, &vertices, &edges);
+            match *self {
+                Spec::Path(n) => assert_path(built, n),
+                Spec::Cycle(n) => assert_cycle(built, n),
+                Spec::Complete(n) => assert_complete(built, n),
+                Spec::Petersen => assert_petersen(built),
+            }
+        }
     }
 
-    fn petersen_add<G: GraphTopologyAddition>()
+    struct Built<G: GraphTopology> {
+        graph: G,
+        vertices: Vec<G::Vertex>,
+        edges: Vec<G::Edge>,
+        initial_vertex_count: usize,
+        initial_edge_count: usize,
+    }
+
+    /// Generates the test for the `append_graph` harness for the given `Spec` expression.
+    macro_rules! min_harness_tests {
+        ($spec:expr) => {
+            #[test]
+            fn append_graph() {
+                run($spec, add_to_empty::<$crate::models::AppendGraph>);
+            }
+        };
+    }
+
+    /// Generates one test per harness for the given `Spec` expression.
+    macro_rules! all_harness_tests {
+        ($spec:expr) => {
+            min_harness_tests!($spec);
+
+            #[test]
+            fn append_graph_non_empty() {
+                run($spec, add_to_standard::<$crate::models::AppendGraph>);
+            }
+
+            #[test]
+            fn graph() {
+                run($spec, add_to_empty::<$crate::models::Graph>);
+            }
+
+            #[test]
+            fn graph_non_empty() {
+                run($spec, add_to_standard::<$crate::models::Graph>);
+            }
+
+            #[test]
+            fn frozen_graph() {
+                run($spec, conv_generate_as::<$crate::models::FrozenGraph>);
+            }
+        };
+    }
+
+    /// Generates the module tree `<group>::<case>::<harness>` for each generator case.
+    ///
+    /// The `all_harnesses` cases run on every harness, the `min_harnesses` cases only on a reduced
+    /// set of harnesses.
+    macro_rules! generator_tests {
+        ($($group:ident {
+            all { $($all_case:ident => $all_generator:expr),+ $(,)? }
+            min { $($min_case:ident => $min_generator:expr),* $(,)? }
+        })+) => {
+            $(
+                mod $group {
+                    use super::*;
+
+                    $(
+                        mod $all_case {
+                            use super::*;
+
+                            all_harness_tests!($all_generator);
+                        }
+                    )+
+
+                    $(
+                        mod $min_case {
+                            use super::*;
+
+                            min_harness_tests!($min_generator);
+                        }
+                    )*
+                }
+            )+
+        };
+    }
+
+    generator_tests! {
+        path {
+            all {
+                small => Spec::Path(4),
+            }
+            min {
+                empty => Spec::Path(0),
+                single_vertex => Spec::Path(1),
+                single_edge => Spec::Path(2),
+                large => Spec::Path(21),
+            }
+        }
+        cycle {
+            all {
+                small_even => Spec::Cycle(4),
+            }
+            min {
+                empty => Spec::Cycle(0),
+                loop_edge => Spec::Cycle(1),
+                multi_edge => Spec::Cycle(2),
+                large_odd => Spec::Cycle(21),
+            }
+        }
+        complete {
+            all {
+                small_even => Spec::Complete(4),
+            }
+            min {
+                empty => Spec::Complete(0),
+                single_vertex => Spec::Complete(1),
+                single_edge => Spec::Complete(2),
+                large_odd => Spec::Complete(13),
+            }
+        }
+    }
+
+    mod petersen {
+        use super::*;
+
+        all_harness_tests!(Spec::Petersen);
+    }
+
+    /// Builds a graph with `harness` and asserts that it matches what `spec` should produce.
+    fn run<G: GraphTopology>(spec: Spec, harness: impl FnOnce(&Spec) -> Built<G>)
     where
         G::Vertex: Debug,
         G::Edge: Debug,
     {
+        let built = harness(&spec);
+        spec.assert(&built);
+    }
+
+    /// Runs `spec` on an empty graph of type `G`.
+    fn add_to_empty<G: GraphTopologyAddition>(spec: &Spec) -> Built<G> {
         let mut graph = G::default();
-        let (vertices, edges) = petersen(&mut graph);
-        assert_petersen(&graph, &vertices, &edges);
+        let (vertices, edges) = spec.generate(&mut graph);
+        Built {
+            graph,
+            vertices,
+            edges,
+            initial_vertex_count: 0,
+            initial_edge_count: 0,
+        }
     }
 
-    fn assert_petersen<G: GraphTopology>(graph: &G, vertices: &[G::Vertex], edges: &[G::Edge])
+    /// Runs `spec` on a non-empty test graph of type `G`.
+    fn add_to_standard<G: GraphTopologyAddition>(spec: &Spec) -> Built<G> {
+        let (mut graph, initial_vertices, initial_edges, _) = G::standard();
+        let (vertices, edges) = spec.generate(&mut graph);
+        Built {
+            graph,
+            vertices,
+            edges,
+            initial_vertex_count: initial_vertices.len(),
+            initial_edge_count: initial_edges.len(),
+        }
+    }
+
+    /// Runs `spec` within `generate_as` for type `G`.
+    fn conv_generate_as<G: GraphTopologyConversion>(spec: &Spec) -> Built<G> {
+        let (graph, vertices, edges) = generate_as::<G>(|graph| spec.generate(graph));
+        Built {
+            graph,
+            vertices,
+            edges,
+            initial_vertex_count: 0,
+            initial_edge_count: 0,
+        }
+    }
+
+    fn assert_path<G: GraphTopology>(built: &Built<G>, n: usize)
     where
         G::Vertex: Debug,
         G::Edge: Debug,
     {
-        assert_element_counts(graph, 10, 15);
-        assert_handles(graph.vertices(), vertices, "vertex");
-        assert_handles(graph.edges(), edges, "edge");
-        assert_no_loops_no_multi_edges(graph);
+        assert_element_counts(built, n, n.saturating_sub(1));
+        assert_handles(built.graph.vertices(), &built.vertices, "vertex");
+        assert_handles(built.graph.edges(), &built.edges, "edge");
+        assert_no_loops(built);
+        assert_no_multi_edges(built);
+        match n {
+            0 => {}
+            1 => assert_eq!(
+                built.graph.degree(built.vertices[0]),
+                0,
+                "path n == 1 should be an isolated vertex"
+            ),
+            _ => {
+                for (i, &v) in built.vertices.iter().enumerate() {
+                    assert_eq!(
+                        built.graph.degree(v),
+                        if i == 0 || i == n - 1 { 1 } else { 2 },
+                        "unexpected degree of vertex {v:?} in path n == {n}"
+                    );
+                }
+            }
+        }
+        assert_path_order(built);
+    }
+
+    fn assert_cycle<G: GraphTopology>(built: &Built<G>, n: usize)
+    where
+        G::Vertex: Debug,
+        G::Edge: Debug,
+    {
+        assert_element_counts(built, n, n);
+        assert_handles(built.graph.vertices(), &built.vertices, "vertex");
+        assert_handles(built.graph.edges(), &built.edges, "edge");
+        if n != 1 {
+            assert_no_loops(built);
+        }
+        if n != 2 {
+            assert_no_multi_edges(built);
+        }
         assert!(
-            graph.vertices().all(|v| graph.degree(v) == 3),
-            "all vertices should have degree 3"
+            built.vertices.iter().all(|&v| built.graph.degree(v) == 2),
+            "all new vertices should have degree 2"
+        );
+        assert_path_order(built);
+        // Asserts the closing edge e(n - 1) == (v(n - 1), v0).
+        if n > 0 {
+            // For n == 1, u == v and this validates the loop. For n == 2, the above asserted one of
+            // the two multi-edges, and this asserts the other.
+            let e = built.edges[n - 1];
+            let u = built.vertices[0];
+            let v = built.vertices[n - 1];
+            let incident_vertices = built.graph.incident_vertices(e);
+            assert!(
+                incident_vertices == (u, v) || incident_vertices == (v, u),
+                "edge {e:?} should have incident vertices {u:?} and {v:?}",
+            );
+        }
+    }
+
+    fn assert_complete<G: GraphTopology>(built: &Built<G>, n: usize)
+    where
+        G::Vertex: Debug,
+        G::Edge: Debug,
+    {
+        assert_element_counts(built, n, n * n.saturating_sub(1) / 2);
+        assert_handles(built.graph.vertices(), &built.vertices, "vertex");
+        assert_handles(built.graph.edges(), &built.edges, "edge");
+        // The predicate in `all` is only executed if `vertices` has any elements, i.e. for n > 0.
+        assert!(
+            built
+                .vertices
+                .iter()
+                .all(|&v| built.graph.degree(v) == n - 1),
+            "all new vertices should have degree {}",
+            n - 1
+        );
+        // Asserts that all pairs of vertices have exactly one edge between them. This also includes
+        // checks for loops and multi-edges. If there are no duplicates, then this implies that all
+        // expected edges were also matched due to the validated counts from above.
+        let mut seen = vec![false; n * n];
+        let position = |v, e| {
+            built
+                .vertices
+                .iter()
+                .position(|&x| x == v)
+                .unwrap_or_else(|| panic!("edge {e:?} has an invalid incident vertex {v:?}"))
+        };
+        for &e in &built.edges {
+            let (u, v) = built.graph.incident_vertices(e);
+            assert_ne!(u, v, "unexpected loop edge {e:?} at vertex {u:?}");
+            let (i, j) = (position(u, e), position(v, e));
+            let (i, j) = (i.min(j), i.max(j));
+            assert!(
+                !seen[i * n + j],
+                "unexpected multi-edge {e:?} between vertices {u:?} and {v:?}"
+            );
+            seen[i * n + j] = true;
+        }
+    }
+
+    fn assert_petersen<G: GraphTopology>(built: &Built<G>)
+    where
+        G::Vertex: Debug,
+        G::Edge: Debug,
+    {
+        assert_element_counts(built, 10, 15);
+        assert_handles(built.graph.vertices(), &built.vertices, "vertex");
+        assert_handles(built.graph.edges(), &built.edges, "edge");
+        assert_no_loops(built);
+        assert_no_multi_edges(built);
+        assert!(
+            built.vertices.iter().all(|&v| built.graph.degree(v) == 3),
+            "all new vertices should have degree 3"
         );
         // Checks that each pair of vertices (u, v) has no common neighbor if they are adjacent, and
         // exactly one common neighbor otherwise.
-        for (i, &v) in vertices.iter().enumerate() {
-            for &u in &vertices[i + 1..] {
-                if graph.are_adjacent(v, u) {
+        for (i, &v) in built.vertices.iter().enumerate() {
+            for &u in &built.vertices[i + 1..] {
+                if built.graph.are_adjacent(v, u) {
                     assert!(
-                        graph.common_neighbors(u, v).next().is_none(),
+                        built.graph.common_neighbors(u, v).next().is_none(),
                         "adjacent vertices {u:?} and {v:?} should not have a common neighbor"
                     );
                 } else {
                     assert_eq!(
-                        graph.common_neighbors(u, v).count(),
+                        built.graph.common_neighbors(u, v).count(),
                         1,
                         "non-adjacent vertices {u:?} and {v:?} should have exactly one common neighbor"
                     );
@@ -157,19 +497,29 @@ mod tests {
     }
 
     fn assert_element_counts<G: GraphTopology>(
-        graph: &G,
+        built: &Built<G>,
         expected_vertex_count: usize,
         expected_edge_count: usize,
     ) {
         assert_eq!(
-            graph.vertex_count(),
-            expected_vertex_count,
-            "unexpected number of vertices"
+            built.graph.vertex_count(),
+            built.initial_vertex_count + expected_vertex_count,
+            "unexpected number of added vertices"
         );
         assert_eq!(
-            graph.edge_count(),
+            built.vertices.len(),
+            expected_vertex_count,
+            "unexpected number of returned vertices"
+        );
+        assert_eq!(
+            built.graph.edge_count(),
+            built.initial_edge_count + expected_edge_count,
+            "unexpected number of added edges"
+        );
+        assert_eq!(
+            built.edges.len(),
             expected_edge_count,
-            "unexpected number of edges"
+            "unexpected number of returned edges"
         );
     }
 
@@ -188,24 +538,53 @@ mod tests {
         }
     }
 
-    fn assert_no_loops_no_multi_edges<G: GraphTopology>(graph: &G)
+    fn assert_no_loops<G: GraphTopology>(built: &Built<G>)
     where
         G::Vertex: Debug,
         G::Edge: Debug,
     {
-        for e in graph.edges() {
-            let (u, v) = graph.incident_vertices(e);
-            assert_ne!(u, v, "unexpected loop edge {e:?}");
+        for &e in &built.edges {
+            let (u, v) = built.graph.incident_vertices(e);
+            assert_ne!(u, v, "unexpected loop edge {e:?} at vertex {u:?}");
         }
-        for v in graph.vertices() {
+    }
+
+    fn assert_no_multi_edges<G: GraphTopology>(built: &Built<G>)
+    where
+        G::Vertex: Debug,
+    {
+        for &v in &built.vertices {
             let mut neighbors = Vec::new();
-            for u in graph.adjacent_vertices(v) {
+            let mut loop_count = 0;
+            for u in built.graph.adjacent_vertices(v) {
+                if u == v {
+                    loop_count += 1;
+                    assert!(loop_count < 3, "unexpected multi-edge loop at vertex {v:?}");
+                } else {
                     assert!(
                         !neighbors.contains(&u),
-                    "unexpected multi-edge between {v:?} and {u:?}"
+                        "unexpected multi-edge between vertices {v:?} and {u:?}"
                     );
                     neighbors.push(u);
                 }
             }
         }
     }
+
+    /// Asserts that each returned edge *ei* connects the returned vertices *vi* and *v(i + 1)*.
+    fn assert_path_order<G: GraphTopology>(built: &Built<G>)
+    where
+        G::Vertex: Debug,
+        G::Edge: Debug,
+    {
+        for (w, &e) in built.vertices.windows(2).zip(&built.edges) {
+            let incident_vertices = built.graph.incident_vertices(e);
+            assert!(
+                incident_vertices == (w[0], w[1]) || incident_vertices == (w[1], w[0]),
+                "edge {e:?} should have incident vertices {:?} and {:?}",
+                w[0],
+                w[1]
+            );
+        }
+    }
+}

src/testing/fixtures.rs

@@ -281,13 +281,12 @@ where
     F: Fn(V) -> Option<u32>,
 {
     let expected = [0, 1, 2, 2, 2, 3, 3, 3, 3, 4];
-    for (i, v) in vertices.iter().enumerate() {
+    for (i, &v) in vertices.iter().enumerate() {
         assert_eq!(
-            actual_for(*v),
+            actual_for(v),
             Some(expected[i]),
-            "unexpected distance from vertex {:?} to vertex {:?}",
-            vertices[0],
-            vertices[i]
+            "unexpected distance from vertex {:?} to vertex {v:?}",
+            vertices[0]
         );
     }
 }
@@ -321,8 +320,8 @@ pub fn assert_standard_unweighted_predecessors_v0<V: Debug + Copy + PartialEq>(
 /// Asserts that the path given as `path_option` is a valid path in `graph`
 ///
 /// Walks the path and asserts that it is `Some`, that it is empty if and only if
-/// `source == target`, that its edges are pairwise incident in the order given, and that it starts
-/// at `source` and ends at `target`.
+/// `source == target` for any `target` in `targets`, that its edges are pairwise incident in the
+/// order given, and that it starts at `source` and ends at any `target` in `targets`.
 pub fn assert_valid_path<G: GraphTopology>(
     graph: &G,
     path_option: Option<Vec<G::Edge>>,