Add subtyping for sum types

1 files changed, 28 insertions, 0 deletions

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerIsSubTypeTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerIsSubTypeTests.java
index b7da683c..a144b78c 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerIsSubTypeTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerIsSubTypeTests.java
@@ -3,7 +3,9 @@ package org.shedlang.compiler.typechecker;
 import org.junit.jupiter.api.Test;
 import org.shedlang.compiler.types.NamespaceName;
 import org.shedlang.compiler.types.StructType;
+import org.shedlang.compiler.types.SumTypeInfo;
 import org.shedlang.compiler.types.Types;
+import org.shedlang.compiler.util.P;
 
 import static org.shedlang.compiler.typechecker.TypeCheckerSubTyping.isSubType;
 import static org.zwobble.precisely.AssertThat.assertThat;
@@ -105,4 +107,30 @@ public class TypeCheckerIsSubTypeTests {
             equalTo(false)
         );
     }
+
+    @Test
+    public void variantIsSubTypeOfSumType() {
+        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 context = TypeCheckerContext.EMPTY
+            .addSumTypeInfo(sumType, new SumTypeInfo(P.orderedSet(variantType1, variantType2)));
+
+        assertThat(isSubType(variantType1, sumType, context), equalTo(true));
+        assertThat(isSubType(variantType2, sumType, context), equalTo(true));
+    }
+
+    @Test
+    public void variantIsNotSuperTypeOfSumType() {
+        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 context = TypeCheckerContext.EMPTY
+            .addSumTypeInfo(sumType, new SumTypeInfo(P.orderedSet(variantType1, variantType2)));
+
+        assertThat(isSubType(sumType, variantType1, context), equalTo(false));
+        assertThat(isSubType(sumType, variantType2, context), equalTo(false));
+    }
 }