From 3224f1c3cd303ef1ed2ea13eb7a2ba4328a64ead Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 17 Sep 2023 17:45:02 +0100
Subject: Check target tuple has the right number of elements

---
 .../typechecker/TypeCheckerAssignTests.java        | 26 ++++++++++++++++++++++
 1 file changed, 26 insertions(+)

(limited to 'src/test/java')

diff --git a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerAssignTests.java b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerAssignTests.java
index b71db8f7..eb2a2db1 100644
--- a/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerAssignTests.java
+++ b/src/test/java/org/shedlang/compiler/typechecker/TypeCheckerAssignTests.java
@@ -7,8 +7,10 @@ import org.shedlang.compiler.ast.untyped.Untyped;
 import org.shedlang.compiler.ast.untyped.UntypedFunctionStatementNode;
 import org.shedlang.compiler.ast.untyped.UntypedNamespaceStatementNode;
 import org.shedlang.compiler.typechecker.errors.CanOnlyAssignToVarError;
+import org.shedlang.compiler.typechecker.errors.TargetTupleHasWrongElementCount;
 import org.shedlang.compiler.typechecker.errors.UnexpectedTypeError;
 import org.shedlang.compiler.typechecker.typesets.TypeSets;
+import org.shedlang.compiler.types.TupleType;
 import org.shedlang.compiler.types.Types;
 import org.shedlang.compiler.util.P;
 
@@ -123,6 +125,30 @@ public class TypeCheckerAssignTests {
         assertThat(error.expected(), equalTo(TypeSets.TUPLE));
     }
 
+    @Test
+    public void whenExpressionAndTargetAreTuplesWithDifferentElementCountThenErrorIsThrown() {
+        var untyped = Untyped.assign(
+            Untyped.targetTuple(List.of(
+                Untyped.targetVal("a"),
+                Untyped.targetVal("b")
+            )),
+            Untyped.reference("x")
+        );
+        var tupleType = new TupleType(List.of(Types.STRING));
+        var context = TypeCheckerContext.EMPTY
+            .enterNamespace(P.map(
+                Map.entry("x", Variable.defined(tupleType, VariableType.VAL))
+            ));
+
+        var error = assertThrows(
+            TargetTupleHasWrongElementCount.class,
+            () -> typeCheckFunctionStatement(untyped, context)
+        );
+
+        assertThat(error.expression(), equalTo(1));
+        assertThat(error.target(), equalTo(2));
+    }
+
     private static TypeCheckerResult<? extends TypedFunctionStatementNode> typeCheckFunctionStatement(
         UntypedFunctionStatementNode untyped,
         TypeCheckerContext context
-- 
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