1 files changed, 15 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 662eebcc..b7eaa0aa 100644
--- a/src/test/java/org/shedlang/compiler/types/TypeSubstitutionTests.java
+++ b/src/test/java/org/shedlang/compiler/types/TypeSubstitutionTests.java
@@ -2,6 +2,7 @@ package org.shedlang.compiler.types;
 
 import org.junit.jupiter.api.Test;
 
+import java.util.List;
 import java.util.Map;
 
 import static org.zwobble.precisely.AssertThat.assertThat;
@@ -82,6 +83,20 @@ public class TypeSubstitutionTests {
     }
 
     @Test
+    public void substitutingTupleSubstitutesElements() {
+        var typeSubstitutionMap = TypeSubstitutionMap.of(
+            Map.entry(TypeParam.forStructType(STRUCT_TYPE, "T"), Types.INT)
+        );
+
+        var result = TypeSubstitution.substitute(
+            Types.tuple(List.of(TypeParam.forStructType(STRUCT_TYPE, "T"))),
+            typeSubstitutionMap
+        );
+
+        assertThat(result, equalTo(Types.tuple(List.of(Types.INT))));
+    }
+
+    @Test
     public void substitutingTypeParamDoesNothingIfTypeParamIsNotInSubstitutionMap() {
         var typeSubstitutionMap = TypeSubstitutionMap.of(
             Map.entry(TypeParam.forStructType(STRUCT_TYPE, "T"), Types.INT)