Adding tests of intersection types hiding and unhiding

Author: radeusgd

test/Base_Tests/src/Main.enso

@@ -10,6 +10,7 @@ import project.Semantic.Error_Spec
 import project.Semantic.Import_Loop.Spec as Import_Loop_Spec
 import project.Semantic.Meta_Spec
 import project.Semantic.Meta_Location_Spec
+import project.Semantic.Multi_Value_As_Type_Refinement_Spec
 import project.Semantic.Multi_Value_Convert_Spec
 import project.Semantic.Multi_Value_Spec
 import project.Semantic.Names_Spec
@@ -132,6 +133,7 @@ main filter=Nothing =
         Maybe_Spec.add_specs suite_builder
         Meta_Spec.add_specs suite_builder
         Meta_Location_Spec.add_specs suite_builder
+        Multi_Value_As_Type_Refinement_Spec.add_specs suite_builder
         Multi_Value_Convert_Spec.add_specs suite_builder
         Multi_Value_Spec.add_specs suite_builder
         Names_Spec.add_specs suite_builder

test/Base_Tests/src/Semantic/Multi_Value_As_Type_Refinement_Spec.enso

@@ -0,0 +1,45 @@
+from Standard.Base import all
+from Standard.Test import all
+import Standard.Base.Errors.Common.Type_Error
+import Standard.Base.Errors.Common.No_Such_Conversion
+import Standard.Base.Errors.Common.No_Such_Method
+
+from project.Semantic.Type_Refinement.Types import A, B, make_a_and_b
+
+id_a (x : A) -> A = x
+id_b (x : B) -> B = x
+
+add_specs suite_builder =
+    suite_builder.group "Multi Value as type refinement" group_builder->
+        group_builder.specify "conversion A -> B should not be available" <|
+            just_a = A.A_Ctor 1
+            Test.expect_panic Type_Error (just_a:B)
+            Test.expect_panic No_Such_Conversion (B.from just_a)
+            Test.expect_panic Type_Error (id_b just_a)
+
+        group_builder.specify "make_a_and_b->A&B presents as both A and B" <|
+            ab = make_a_and_b
+            ab.is_a A . should_be_true
+            ab.is_a B . should_be_true
+            (ab:A).to_text . should_equal "(A_Ctor 1)"
+            (ab:B).to_text . should_equal "(B_Ctor (A_Ctor 1))"
+            (id_a ab).to_text . should_equal "(A_Ctor 1)"
+            (id_b ab).to_text . should_equal "(B_Ctor (A_Ctor 1))"
+
+        group_builder.specify "after passing A&B value to a function expecting A argument, B becomes hidden" <|
+            ab = make_a_and_b
+            a2 = id_a ab
+            a2.is_a A . should_be_true
+            a2.is_a B . should_be_false
+
+            # Passing a2 to a function expecting B fails because B part was hidden
+            Test.expect_panic Type_Error (id_b a2)
+
+            # But it can be uncovered via explicit cast
+            (a2:B).to_text . should_equal "(B_Ctor (A_Ctor 1))"
+            (id_b (a2:B)).to_text . should_equal "(B_Ctor (A_Ctor 1))"
+
+main filter=Nothing =
+    suite = Test.build suite_builder->
+        add_specs suite_builder
+    suite.run_with_filter filter

test/Base_Tests/src/Semantic/Multi_Value_Spec.enso

@@ -163,7 +163,6 @@ add_specs suite_builder =
             Test.expect_panic Type_Error <|
                 _ = a_or_b : (A&B)
 
-        # This test is failing
         group_builder.specify "B --> (A|C) is possible" <|
             b = B.B 42
             a_or_c = b : (A|C)

test/Base_Tests/src/Semantic/Type_Refinement/Hidden_Conversions.enso

@@ -0,0 +1,7 @@
+private
+
+from project.Semantic.Type_Refinement.Types import A, B
+
+## This conversion should only be imported in `Type_Refinement.Types` and nowhere else.
+B.from (that : A) -> B =
+    B.B_Ctor that

test/Base_Tests/src/Semantic/Type_Refinement/Types.enso

@@ -0,0 +1,12 @@
+from project.Semantic.Type_Refinement.Hidden_Conversions import all
+
+type A
+    A_Ctor x
+
+type B
+    B_Ctor x
+
+make_a_and_b -> A & B =
+    a = A.A_Ctor 1
+    # Relies on the hidden conversion
+    (a : A & B)