Error if trying to assign to variable not in scope

2 files changed, 18 insertions, 2 deletions

diff --git a/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java b/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
index 7656e89..ff74d1b 100644
--- a/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
+++ b/src/test/java/org/zwobble/couscous/tests/interpreter/EvaluatorTests.java
@@ -11,6 +11,7 @@ import org.zwobble.couscous.ast.TernaryConditionalNode;
 import org.zwobble.couscous.interpreter.ConditionMustBeBoolean;
 import org.zwobble.couscous.interpreter.Environment;
 import org.zwobble.couscous.interpreter.NoSuchMethod;
+import org.zwobble.couscous.interpreter.StackFrameBuilder;
 import org.zwobble.couscous.interpreter.UnexpectedValueType;
 import org.zwobble.couscous.interpreter.WrongNumberOfArguments;
 import org.zwobble.couscous.values.ConcreteType;
@@ -35,7 +36,7 @@ public class EvaluatorTests {
         val arg = new FormalArgumentNode(42, StringValue.REF, "x");
         val environment = new Environment(
             new MapBackedProject(ImmutableMap.of()),
-            ImmutableMap.of(arg.getId(), new StringValue("[initial value]")));
+            new StackFrameBuilder().declare(arg, new StringValue("[initial value]")).build());
         val result = eval(environment, assign(arg, literal("[updated value]")));
         assertEquals(new StringValue("[updated value]"), result);
     }
diff --git a/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java b/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java
index d461221..66a1f8b 100644
--- a/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java
+++ b/src/test/java/org/zwobble/couscous/tests/interpreter/InterpreterTests.java
@@ -10,6 +10,7 @@ import org.zwobble.couscous.ast.LiteralNode;
 import org.zwobble.couscous.ast.MethodNode;
 import org.zwobble.couscous.ast.ReturnNode;
 import org.zwobble.couscous.interpreter.Interpreter;
+import org.zwobble.couscous.interpreter.VariableNotInScope;
 import org.zwobble.couscous.interpreter.WrongNumberOfArguments;
 import org.zwobble.couscous.values.ConcreteType;
 import org.zwobble.couscous.values.InterpreterValue;
@@ -19,6 +20,7 @@ import com.google.common.collect.ImmutableMap;
 
 import static java.util.Arrays.asList;
 import static org.junit.Assert.assertEquals;
+import static org.zwobble.couscous.ast.LiteralNode.literal;
 import static org.zwobble.couscous.ast.LocalVariableDeclarationNode.localVariableDeclaration;
 import static org.zwobble.couscous.ast.MethodNode.staticMethod;
 import static org.zwobble.couscous.ast.VariableReferenceNode.reference;
@@ -91,7 +93,7 @@ public class InterpreterTests {
     }
     
     @Test
-    public void canDeclareVariableAndAssignValues() {
+    public void canDeclareVariableAndThenAssignValues() {
         val localVariableDeclaration = localVariableDeclaration(
             42, StringValue.REF, "x", LiteralNode.literal("[initial value]"));
         val method = staticMethod("hello")
@@ -102,6 +104,19 @@ public class InterpreterTests {
         
         assertEquals(new StringValue("[updated value]"), result);
     }
+    
+    @Test
+    public void errorIfTryingToAssignToVariableNotInScope() {
+        val localVariableDeclaration = localVariableDeclaration(
+            42, StringValue.REF, "x", literal(""));
+        val method = staticMethod("hello")
+            .statement(new ExpressionStatementNode(new Assignment(reference(localVariableDeclaration), LiteralNode.literal("[updated value]"))));
+
+        val exception = assertThrows(VariableNotInScope.class,
+            () -> runMethod(method));
+        
+        assertEquals(new VariableNotInScope(42), exception);
+    }
 
     private InterpreterValue runMethod(MethodNode.MethodNodeBuilder methodBuilder, InterpreterValue... arguments) {
         val method = methodBuilder.build();