fix(std/testing): invalid dates assertion equality (#7230)

std/testing/asserts.ts

@@ -95,6 +95,13 @@ export function equal(c: unknown, d: unknown): boolean {
       return String(a) === String(b);
     }
     if (a instanceof Date && b instanceof Date) {
+      const aTime = a.getTime();
+      const bTime = b.getTime();
+      // Check for NaN equality manually since NaN is not
+      // equal to itself.
+      if (Number.isNaN(aTime) && Number.isNaN(bTime)) {
+        return true;
+      }
       return a.getTime() === b.getTime();
     }
     if (Object.is(a, b)) {

std/testing/asserts_test.ts

@@ -50,6 +50,9 @@ Deno.test("testingEqual", function (): void {
       new Date(2019, 0, 3, 4, 20, 1, 20),
     ),
   );
+  assert(equal(new Date("Invalid"), new Date("Invalid")));
+  assert(!equal(new Date("Invalid"), new Date(2019, 0, 3)));
+  assert(!equal(new Date("Invalid"), new Date(2019, 0, 3, 4, 20, 1, 10)));
   assert(equal(new Set([1]), new Set([1])));
   assert(!equal(new Set([1]), new Set([2])));
   assert(equal(new Set([1, 2, 3]), new Set([3, 2, 1])));
@@ -141,6 +144,10 @@ Deno.test("testingNotEquals", function (): void {
     new Date(2019, 0, 3, 4, 20, 1, 10),
     new Date(2019, 0, 3, 4, 20, 1, 20),
   );
+  assertNotEquals(
+    new Date("invalid"),
+    new Date(2019, 0, 3, 4, 20, 1, 20),
+  );
   let didThrow;
   try {
     assertNotEquals("Raptor", "Raptor");
@@ -340,6 +347,7 @@ Deno.test({
     assertEquals(10, 10);
     assertEquals("abc", "abc");
     assertEquals({ a: 10, b: { c: "1" } }, { a: 10, b: { c: "1" } });
+    assertEquals(new Date("invalid"), new Date("invalid"));
   },
 });
 
@@ -431,6 +439,21 @@ Deno.test({
         "",
       ].join("\n"),
     );
+    assertThrows(
+      (): void =>
+        assertEquals(
+          new Date("invalid"),
+          new Date(2019, 0, 3, 4, 20, 1, 20),
+        ),
+      AssertionError,
+      [
+        "Values are not equal:",
+        ...createHeader(),
+        removed(`-   ${new Date("invalid")}`),
+        added(`+   ${new Date(2019, 0, 3, 4, 20, 1, 20).toISOString()}`),
+        "",
+      ].join("\n"),
+    );
   },
 });