Support arrays of any size in collection matchers.

This was possible thanks to the [stabilisation of minimal const generics
support](rust-lang/rust#79135) in Rust 1.51.

Author: gcapizzi

src/matchers/collection.rs

@@ -4,8 +4,7 @@ use std::marker::PhantomData;
 
 /// Matches if `actual` contains `element`.
 ///
-/// Supports [arrays] of up to 256 elements, [`Vec`]s, [`VecDeque`]s, [`LinkedList`]s, [`HashSet`]s
-/// and [`BTreeSet`]s.
+/// Supports [arrays] [`Vec`]s, [`VecDeque`]s, [`LinkedList`]s, [`HashSet`]s and [`BTreeSet`]s.
 ///
 /// [array]: https://doc.rust-lang.org/std/primitive.array.html
 /// [`Vec`]: https://doc.rust-lang.org/std/vec/struct.Vec.html
@@ -44,8 +43,7 @@ impl<T: std::fmt::Debug, V: Collection<T>> Matcher<V> for ContainMatcher<T> {
 
 /// Matches if `actual` is empty.
 ///
-/// Supports [arrays] of up to 256 elements, [`Vec`]s, [`VecDeque`]s, [`LinkedList`]s, [`HashSet`]s
-/// and [`BTreeSet`]s.
+/// Supports [arrays], [`Vec`]s, [`VecDeque`]s, [`LinkedList`]s, [`HashSet`]s and [`BTreeSet`]s.
 ///
 /// [array]: https://doc.rust-lang.org/std/primitive.array.html
 /// [`Vec`]: https://doc.rust-lang.org/std/vec/struct.Vec.html
@@ -88,38 +86,15 @@ pub trait Collection<T> {
     fn empty(&self) -> bool;
 }
 
-macro_rules! array {
-    ($($N:expr),+) => {
-        $(
-            #[doc(hidden)]
-            impl<T: std::cmp::PartialEq> Collection<T> for [T; $N] {
-                fn contains_element(&self, element: &T) -> bool {
-                    self.contains(element)
-                }
-
-                fn empty(&self) -> bool {
-                    self.is_empty()
-                }
-            }
-        )+
+impl<T: std::cmp::PartialEq, const N: usize> Collection<T> for [T; N] {
+    fn contains_element(&self, element: &T) -> bool {
+        self.contains(element)
     }
-}
 
-array!(
-    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
-    26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
-    50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73,
-    74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97,
-    98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116,
-    117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135,
-    136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154,
-    155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173,
-    174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192,
-    193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211,
-    212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230,
-    231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 249,
-    250, 251, 252, 253, 254, 255, 256
-);
+    fn empty(&self) -> bool {
+        self.is_empty()
+    }
+}
 
 impl<T: std::cmp::PartialEq> Collection<T> for std::vec::Vec<T> {
     fn contains_element(&self, element: &T) -> bool {
@@ -211,41 +186,9 @@ mod tests {
     }
 
     #[test]
-    fn arrays_with_up_to_256_elements_are_collections() {
-        assert!([
-            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
-            24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,
-            46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67,
-            68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89,
-            90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108,
-            109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125,
-            126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142,
-            143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
-            160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176,
-            177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193,
-            194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210,
-            211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227,
-            228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244,
-            245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255
-        ]
-        .contains_element(&255));
-        assert!(![
-            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
-            24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45,
-            46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67,
-            68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89,
-            90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108,
-            109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125,
-            126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142,
-            143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
-            160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176,
-            177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193,
-            194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210,
-            211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227,
-            228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244,
-            245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255
-        ]
-        .empty());
+    fn arrays_are_collections() {
+        assert!([1, 2, 3].contains_element(&2));
+        assert!(![1, 2, 3].empty());
     }
 
     #[test]