Fix formatting of long multiline if/is expressions.

crates/aiken-lang/src/format.rs

@@ -1323,10 +1323,7 @@ impl<'comments> Formatter<'comments> {
                             .group()
                     };
 
-                    break_("", " ")
-                        .append("is")
-                        .append(break_("", " "))
-                        .append(is)
+                    break_("", " ").append("is ").append(is)
                 }
                 None => nil(),
             })

crates/aiken-lang/src/tests/check.rs

@@ -3264,3 +3264,15 @@ fn constant_usage() {
         }] if name == "some_string_constant"
     ));
 }
+
+#[test]
+fn wrong_arity_on_known_builtin() {
+    let source_code = r#"
+        const foo: Option<Int> = Some()
+    "#;
+
+    assert!(matches!(
+        check_validator(parse(source_code)),
+        Err((_, Error::IncorrectFunctionCallArity { .. }))
+    ))
+}

crates/aiken-lang/src/tests/format.rs

@@ -1388,3 +1388,35 @@ fn callback_and_op() {
         "#
     );
 }
+
+#[test]
+fn multiline_if_is() {
+    assert_format!(
+        r#"
+        fn foo() {
+            if first_asset
+            is
+            Pair(first_asset_policy, first_asset_tokens): Pair<PolicyId, Data> {
+                True
+                } else {
+                    False }
+        }
+        "#
+    );
+}
+
+#[test]
+fn multiline_if_is_2() {
+    assert_format!(
+        r#"
+        fn foo() {
+            if [1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0]
+            is
+            Pair(first_asset_policy, first_asset_tokens): Pair<PolicyId, Data> {
+                True
+                } else {
+                    False }
+        }
+        "#
+    );
+}

crates/aiken-lang/src/tests/snapshots/multiline_if_is.snap

@@ -0,0 +1,12 @@
+---
+source: crates/aiken-lang/src/tests/format.rs
+description: "Code:\n\nfn foo() {\n    if first_asset\n    is\n    Pair(first_asset_policy, first_asset_tokens): Pair<PolicyId, Data> {\n        True\n        } else {\n            False }\n}\n"
+---
+fn foo() {
+  if first_asset
+  is Pair(first_asset_policy, first_asset_tokens): Pair<PolicyId, Data> {
+    True
+  } else {
+    False
+  }
+}

crates/aiken-lang/src/tests/snapshots/multiline_if_is_2.snap

@@ -0,0 +1,15 @@
+---
+source: crates/aiken-lang/src/tests/format.rs
+description: "Code:\n\nfn foo() {\n    if [1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0]\n    is\n    Pair(first_asset_policy, first_asset_tokens): Pair<PolicyId, Data> {\n        True\n        } else {\n            False }\n}\n"
+---
+fn foo() {
+  if [
+    1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6,
+    7, 8, 9, 0,
+  ]
+  is Pair(first_asset_policy, first_asset_tokens): Pair<PolicyId, Data> {
+    True
+  } else {
+    False
+  }
+}