Improve isolation of README example tests (#65)

Author: Shristi-Goel

CHANGELOG.md

@@ -55,6 +55,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   [\#49](https://github.com/mllam/weather-model-graphs/pull/49),
   [\#54](https://github.com/mllam/weather-model-graphs/pull/54), @leifdenby
 
+- Improve isolation of README example tests by executing each code block in an isolated namespace.
+  [#65](https://github.com/mllam/weather-model-graphs/pull/64) @Shristi-Goel
+
 ## [v0.2.0](https://github.com/mllam/weather-model-graphs/releases/tag/v0.2.0)
 
 ### Added

tests/test_readme.py

@@ -18,4 +18,4 @@ def test_readme_example(codeblock_example: str):
     """
     Check that execution of the python code block in the README does not raise an exception.
     """
-    exec(codeblock_example)
+    exec(codeblock_example, {})