Test that mints without a cap are unmintable (#3495)

Test that if the `cap` field of an etching is unset, it is treated as being
zero, and the rune is unmintable.Test that if the `cap` field of an etching is
unset, it is treated as being zero, and the rune is unmintable.

src/runes.rs

@@ -4770,6 +4770,91 @@ mod tests {
     );
   }
 
+  #[test]
+  fn open_mints_without_a_cap_are_unmintable() {
+    let context = Context::builder().arg("--index-runes").build();
+
+    let (txid0, id) = context.etch(
+      Runestone {
+        etching: Some(Etching {
+          rune: Some(Rune(RUNE)),
+          terms: Some(Terms {
+            amount: Some(1000),
+            offset: (None, Some(2)),
+            ..default()
+          }),
+          ..default()
+        }),
+        ..default()
+      },
+      1,
+    );
+
+    context.assert_runes(
+      [(
+        id,
+        RuneEntry {
+          block: id.block,
+          etching: txid0,
+          spaced_rune: SpacedRune {
+            rune: Rune(RUNE),
+            spacers: 0,
+          },
+          timestamp: id.block,
+          terms: Some(Terms {
+            amount: Some(1000),
+            offset: (None, Some(2)),
+            ..default()
+          }),
+          ..default()
+        },
+      )],
+      [],
+    );
+
+    context.core.broadcast_tx(TransactionTemplate {
+      inputs: &[(2, 0, 0, Witness::new())],
+      op_return: Some(
+        Runestone {
+          edicts: vec![Edict {
+            id,
+            amount: 1000,
+            output: 0,
+          }],
+          mint: Some(id),
+          ..default()
+        }
+        .encipher(),
+      ),
+      ..default()
+    });
+
+    context.mine_blocks(1);
+
+    context.assert_runes(
+      [(
+        id,
+        RuneEntry {
+          block: id.block,
+          spaced_rune: SpacedRune {
+            rune: Rune(RUNE),
+            spacers: 0,
+          },
+          timestamp: id.block,
+          mints: 0,
+          etching: txid0,
+          terms: Some(Terms {
+            amount: Some(1000),
+            offset: (None, Some(2)),
+            ..default()
+          }),
+          ..default()
+        },
+      )],
+      [],
+    );
+  }
+
   #[test]
   fn open_mint_claims_can_use_split() {
     let context = Context::builder().arg("--index-runes").build();