1 files changed, 28 insertions, 0 deletions
diff --git a/src/test/java/org/shedlang/compiler/types/TypeSubstitutionTests.java b/src/test/java/org/shedlang/compiler/types/TypeSubstitutionTests.java
index 2e2bd08e..210e4c18 100644
--- a/src/test/java/org/shedlang/compiler/types/TypeSubstitutionTests.java
+++ b/src/test/java/org/shedlang/compiler/types/TypeSubstitutionTests.java
@@ -14,6 +14,34 @@ public class TypeSubstitutionTests {
     private static final SimpleStructType STRUCT_TYPE_2 = Types.struct(NAMESPACE_NAME, "Struct2");
 
     @Test
+    public void substitutingEffectParamDoesNothingIfEffectParamIsNotInSubstitutionMap() {
+        var typeSubstitutionMap = TypeSubstitutionMap.of(
+            Map.entry(EffectParam.forStructType(STRUCT_TYPE, "E"), Effects.IO)
+        );
+
+        var result = TypeSubstitution.substituteEffect(
+            EffectParam.forStructType(STRUCT_TYPE_2, "E"),
+            typeSubstitutionMap
+        );
+
+        assertThat(result, equalTo(EffectParam.forStructType(STRUCT_TYPE_2, "E")));
+    }
+
+    @Test
+    public void substitutingEffectParamChangesEffectParamToCorrespondingEffect() {
+        var typeSubstitutionMap = TypeSubstitutionMap.of(
+            Map.entry(EffectParam.forStructType(STRUCT_TYPE, "E"), Effects.IO)
+        );
+
+        var result = TypeSubstitution.substituteEffect(
+            EffectParam.forStructType(STRUCT_TYPE, "E"),
+            typeSubstitutionMap
+        );
+
+        assertThat(result, equalTo(Effects.IO));
+    }
+
+    @Test
     public void substitutingBoolDoesNothing() {
         var typeSubstitutionMap = TypeSubstitutionMap.of(
             Map.entry(TypeParam.forStructType(STRUCT_TYPE, "T"), Types.INT)