1 files changed, 104 insertions, 0 deletions
diff --git a/src/test/java/org/zwobble/couscous/tests/BackendMethodTests.java b/src/test/java/org/zwobble/couscous/tests/BackendMethodTests.java
new file mode 100644
index 0000000..b55a2ca
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+++ b/src/test/java/org/zwobble/couscous/tests/BackendMethodTests.java
@@ -0,0 +1,104 @@
+package org.zwobble.couscous.tests;
+
+import org.junit.Test;
+import org.zwobble.couscous.ast.AssignmentNode;
+import org.zwobble.couscous.ast.ClassNode;
+import org.zwobble.couscous.ast.ExpressionStatementNode;
+import org.zwobble.couscous.ast.LiteralNode;
+import org.zwobble.couscous.ast.MethodNode;
+import org.zwobble.couscous.ast.ReturnNode;
+import org.zwobble.couscous.values.PrimitiveValue;
+import org.zwobble.couscous.values.PrimitiveValues;
+import org.zwobble.couscous.values.StringValue;
+
+import static java.util.Arrays.asList;
+import static org.junit.Assert.assertEquals;
+import static org.zwobble.couscous.ast.FormalArgumentNode.formalArg;
+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.VariableDeclaration.var;
+import static org.zwobble.couscous.ast.VariableReferenceNode.reference;
+import static org.zwobble.couscous.values.PrimitiveValues.value;
+
+import lombok.val;
+
+public abstract class BackendMethodTests {
+    @Test
+    public void methodWithNoStatementsReturnsUnit() {
+        val method = staticMethod("hello");
+        val result = runMethod(method);
+        
+        assertEquals(PrimitiveValues.UNIT, result);
+    }
+    
+    @Test
+    public void canReturnLiteralValue() {
+        val method = staticMethod("hello")
+            .statement(new ReturnNode(literal("hello, world!")));
+        val result = runMethod(method);
+        
+        assertEquals(value("hello, world!"), result);
+    }
+    @Test
+    public void canPassValueToMethod() {
+        val arg = formalArg(var(42, "x", StringValue.REF));
+        val method = staticMethod("hello")
+            .argument(arg)
+            .statement(new ReturnNode(reference(arg)));
+        val result = runMethod(method, value("hello, world!"));
+        
+        assertEquals(value("hello, world!"), result);
+    }
+    
+    @Test
+    public void canReassignValueToArgument() {
+        val arg = formalArg(var(42, "x", StringValue.REF));
+        val method = staticMethod("hello")
+            .argument(arg)
+            .statement(new ExpressionStatementNode(new AssignmentNode(reference(arg), LiteralNode.literal("[updated value]"))))
+            .statement(new ReturnNode(reference(arg)));
+        val result = runMethod(method, value("[initial value]"));
+        
+        assertEquals(value("[updated value]"), result);
+    }
+    
+    @Test
+    public void canDeclareVariable() {
+        val localVariableDeclaration = localVariableDeclaration(
+            42, "x", StringValue.REF, LiteralNode.literal("[initial value]"));
+        val method = staticMethod("hello")
+            .statement(localVariableDeclaration)
+            .statement(new ReturnNode(reference(localVariableDeclaration)));
+        val result = runMethod(method);
+        
+        assertEquals(value("[initial value]"), result);
+    }
+    
+    @Test
+    public void canDeclareVariableAndThenAssignValues() {
+        val localVariableDeclaration = localVariableDeclaration(
+            42, "x", StringValue.REF, LiteralNode.literal("[initial value]"));
+        val method = staticMethod("hello")
+            .statement(localVariableDeclaration)
+            .statement(new ExpressionStatementNode(new AssignmentNode(reference(localVariableDeclaration), LiteralNode.literal("[updated value]"))))
+            .statement(new ReturnNode(reference(localVariableDeclaration)));
+        val result = runMethod(method);
+        
+        assertEquals(value("[updated value]"), result);
+    }
+
+    protected PrimitiveValue runMethod(MethodNode.MethodNodeBuilder methodBuilder, PrimitiveValue... arguments) {
+        val method = methodBuilder.build();
+        val className = "com.example.Program";
+        val classNode = ClassNode.builder(className)
+            .method(method)
+            .build();
+        
+        val runner = buildMethodRunner();
+        return runner.runMethod(classNode, method.getName(), asList(arguments));
+    }
+    
+    protected abstract MethodRunner buildMethodRunner();
+        
+}