Fix Copy equality/hashCode contract

src/main/java/io/zold/api/Copies.java

@@ -116,7 +116,7 @@ public int compareTo(final Copy other) {
         @Override
         public boolean equals(final Object obj) {
             return obj instanceof Copy
-                && this.compareTo((Copy) obj) == 0;
+                && this.wlt.equals(((Copy) obj).wlt);
         }
 
         @Override

src/test/java/io/zold/api/CopiesTest.java

@@ -41,13 +41,60 @@ void groupsRemotesScoresIntoSingleCopy() {
         );
     }
 
+    @Test
+    void keepsIdentityWhenCopyGetsRemote() {
+        final Copies.Copy copy = new Copies.Copy(
+            new Wallet.Fake(1L),
+            CopiesTest.remote("a")
+        );
+        MatcherAssert.assertThat(
+            "copy identity is stable when a remote is added",
+            copy.with(CopiesTest.remote("b")),
+            new IsEqual<>(copy)
+        );
+    }
+
+    @Test
+    void keepsHashCodeWhenCopyGetsRemote() {
+        final Copies.Copy copy = new Copies.Copy(
+            new Wallet.Fake(1L),
+            CopiesTest.remote("a")
+        );
+        MatcherAssert.assertThat(
+            "hash code matches equality after adding a remote",
+            copy.with(CopiesTest.remote("b")).hashCode(),
+            new IsEqual<>(copy.hashCode())
+        );
+    }
+
+    @Test
+    void distinguishesCopiesWithDifferentWalletsAndSameScore() {
+        MatcherAssert.assertThat(
+            "different wallets are not equal even with the same score",
+            new Copies.Copy(
+                new Wallet.Fake(1L),
+                CopiesTest.remote("a")
+            ).equals(
+                new Copies.Copy(
+                    new Wallet.Fake(2L),
+                    CopiesTest.remote("b")
+                )
+            ),
+            new IsEqual<>(false)
+        );
+    }
+
     private static Iterable<Copies.Copy> copies() {
         return new Copies(
             1L,
             new IterableOf<>(
-                new Remote.Fake(new RtScore(new IterableOf<>(new TextOf("a")))),
-                new Remote.Fake(new RtScore(new IterableOf<>(new TextOf("b"))))
+                CopiesTest.remote("a"),
+                CopiesTest.remote("b")
             )
         );
     }
+
+    private static Remote remote(final String suffix) {
+        return new Remote.Fake(new RtScore(new IterableOf<>(new TextOf(suffix))));
+    }
 }