E0067: rules_outside_test

E0067 rules_outside_test — a rules block outside a cell test.

A compile-time error of soma check, the checker of the Soma programming language (soma explain E0067).

The rule

Test rules (assert, property) belong inside a cell test with a rules block; a rules block in an ordinary cell is refused because those rules would never run. Move them to their own test cell, cell test CartTests { rules { ... } }, which can call the program's handlers unqualified.

A program that triggers it

cell Cart {
    memory {
        items: Map<String, Int> [persistent]
    }
    on add(sku: String, qty: Int) {
        items.set(sku, (items.get(sku) ?? 0) + qty)
        return items.get(sku)
    }
    rules {
        assert add("apple", 2) == 2
    }
}

What soma check prints:

$ soma check wrong.cell
error: cell 'Cart' has 1 test rule(s) (assert / property) but is not a test cell — they would never run: move them to `cell test CartTests { rules { … } }`
  --> wrong.cell:9:5
  |
9 |     rules {
  |     ^
  = code: E0067
✗ 1 error(s), 0 warning(s).

The fix field of soma check --json: they would never run: move them to `cell test CartTests { rules { … } }`

The fix

3 lines are added after line 8.

--- wrong.cell
+++ right.cell
@@ -7,4 +7,7 @@
         return items.get(sku)
     }
+}
+
+cell test CartTests {
     rules {
         assert add("apple", 2) == 2

With the fix, soma check accepts the program:

$ soma check right.cell
✓ All checks passed.