add tests

tests/test_predicate.py

@@ -13,12 +13,13 @@
 """This module contains tests for PDDL predicates."""
 from pddl.core import Predicate
 from pddl.logic.helpers import variables
+from pddl.logic.predicates import EqualTo
 
 
 class TestPredicateSimpleInitialisation:
     """Test simple predicate initialisation."""
 
-    def setup(self):
+    def setup_method(self):
         """Set up the tests."""
         self.a, self.b = variables("a b")
         self.predicate = Predicate("P", self.a, self.b)
@@ -34,3 +35,28 @@ def test_variables(self):
     def test_arity(self):
         """Test arity property."""
         assert self.predicate.arity == 2
+
+
+class TestEqualToPredicate:
+    """Test the eaual to predicate."""
+
+    def setup_method(self):
+        """Set up the tests."""
+        self.left, self.right = variables("l r")
+        self.equal_to = EqualTo(self.left, self.right)
+
+    def test_left(self):
+        assert self.equal_to.left == self.left
+
+    def test_right(self):
+        assert self.equal_to.right == self.right
+
+    def test_to_equal(self):
+        other = EqualTo(self.left, self.right)
+        assert self.equal_to == other
+
+    def test_to_str(self):
+        assert str(self.equal_to) == f"(= {str(self.left)} {str(self.right)})"
+
+    def test_to_repr(self):
+        assert repr(self.equal_to) == f"EqualTo({repr(self.left)}, {repr(self.right)})"