added tests folder

test/dropdown.py

@@ -0,0 +1,15 @@
+import gradio as gr
+
+
+def debug_click(drop_down):
+    print(drop_down)
+    return "yes"
+
+
+with gr.Blocks() as demo:
+    drop_down = gr.Dropdown(
+        choices=["first", "second"], type="index", interactive=True, multiselect=False
+    )
+    txt = gr.Textbox()
+    btn = gr.Button("Clear")
+    btn.click(debug_click, inputs=drop_down, outputs=txt)