Add TypeInfos.subtypes()

1 files changed, 33 insertions, 0 deletions

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeInfosTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeInfosTests.java
index 71386dfd..9697ef50 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeInfosTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeInfosTests.java
@@ -44,4 +44,37 @@ public class TypeInfosTests {
             equalTo(Types.TOP)
         ));
     }
+    @Test
+    public void subtypesOfTypeIncludeThatTypeAndBottom() {
+        var typeInfos = TypeInfos.EMPTY;
+
+        var supertypes = typeInfos.subtypes(Types.INT);
+
+        assertThat(supertypes, isSequence(
+            equalTo(Types.INT),
+            equalTo(Types.BOTTOM)
+        ));
+    }
+
+    @Test
+    public void subtypesOfSumIncludeVariants() {
+        var namespaceName = NamespaceName.of("Example", "Project");
+        var sumType = Types.sum(namespaceName, "Sum");
+        var variantType1 = Types.struct(namespaceName, "Variant1");
+        var variantType2 = Types.struct(namespaceName, "Variant2");
+        var typeInfos = TypeInfos.EMPTY
+            .addSumTypeInfo(sumType, new SumTypeInfo(P.orderedSet(
+                variantType1,
+                variantType2
+            )));
+
+        var supertypes = typeInfos.subtypes(sumType);
+
+        assertThat(supertypes, isSequence(
+            equalTo(sumType),
+            equalTo(variantType1),
+            equalTo(variantType2),
+            equalTo(Types.BOTTOM)
+        ));
+    }
 }