add basic api test

test/api.js

@@ -0,0 +1,17 @@
+var transform = require("../lib/6to5/transformation/transform");
+var assert    = require("assert");
+var File      = require("../lib/6to5/file");
+
+suite("api", function () {
+  test("{ code: false }", function () {
+    var result = transform("foo('bar');", { code: false });
+    assert.ok(!result.code);
+  });
+
+  test("addDeclaration unknown", function () {
+    var file = new File;
+    assert.throws(function () {
+      file.addDeclaration("foob");
+    }, /unknown declaration foob/);
+  });
+});