Test bound type param as subtype

1 files changed, 29 insertions, 1 deletions

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerIsSubTypeTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerIsSubTypeTests.java
index af4d46e4..5f7fede9 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerIsSubTypeTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerIsSubTypeTests.java
@@ -13,7 +13,7 @@ import java.util.Map;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.shedlang.compiler.typechecker.TypeCheckerSubTyping.isSubType;
 import static org.zwobble.precisely.AssertThat.assertThat;
-import static org.zwobble.precisely.Matchers.equalTo;
+import static org.zwobble.precisely.Matchers.*;
 
 public class TypeCheckerIsSubTypeTests {
     // == General ==
@@ -135,12 +135,40 @@ public class TypeCheckerIsSubTypeTests {
         );
         var result = constraints.solve(Sources.NULL);
 
+        assertThat(constraints.typeBounds().get(typeParam), allOf(
+            has("lower", x -> x.lower(), isSequence(equalTo(Types.INT))),
+            has("upper", x -> x.upper(), isSequence())
+        ));
         assertThat(result, equalTo(TypeSubstitutionMap.of(
             Map.entry(typeParam, Types.INT)
         )));
     }
 
     @Test
+    public void whenSubtypeIsBoundTypeParamThenUpperBoundIsAddedToType() {
+        var typeParam = TypeParam.forStructType(
+            Types.struct(NamespaceName.of("Example"), "Struct"),
+            "T"
+        );
+
+        var constraints = TypeCheckerSubTyping.addSubtypeConstraint(
+            typeParam,
+            Types.INT,
+            Sources.NULL,
+            TypeCheckerSubTyping.constraints(List.of(typeParam), TypeInfos.EMPTY)
+        );
+        var result = constraints.solve(Sources.NULL);
+
+        assertThat(constraints.typeBounds().get(typeParam), allOf(
+            has("lower", x -> x.lower(), isSequence()),
+            has("upper", x -> x.upper(), isSequence(equalTo(Types.INT)))
+        ));
+        assertThat(result, equalTo(TypeSubstitutionMap.of(
+            Map.entry(typeParam, Types.BOTTOM)
+        )));
+    }
+
+    @Test
     public void whenSupertypeIsFreeTypeParamThenOtherTypesAreNotSubtype() {
         var typeParam = TypeParam.forStructType(
             Types.struct(NamespaceName.of("Example"), "Struct"),