Update chapter3-base-tests.md

tests/chapter3-base-tests.md

@@ -21,6 +21,27 @@ Make sure you have the expected default values for `HSTEP`, `VSTEP`,
     >>> browser.HEIGHT
     600
 
+
+Notes
+=====
+
+You might need to modify the `__repr__` method on `Text` and `Tag`
+if you factored your project into multiple files:  (This is especially
+true if you see a mismatched output of the form `<layout.Tag object at ...>`)
+
+```
+class Text:
+    ...
+    def __repr__(self):
+        return "Text('{}')".format(self.text)
+
+class Tag:
+    ...
+    def __repr__(self):
+        return "Tag('{}')".format(self.tag)
+```
+
+
 Testing `lex`
 -------------