add pytest-env

book/testing/Chapter.ipynb

@@ -549,6 +549,57 @@
    "source": [
     "!pytest -vv --diff-width=60"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Using Environment Variables with `pytest-env`"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "How to use environment variables when testing your code?\n",
+    "\n",
+    "It's important to not mix up your test environment and local environment, especially when you want to define environment variables specifically for your tests.\n",
+    "\n",
+    "For this case, use `pytest-env`.\n",
+    "\n",
+    "`pytest-env` is a pytest plugin to define your environment variables in a pytest.ini file.\n",
+    "\n",
+    "Those variables will be isolated from the local environment, perfect for writing and running tests."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "!pip install pytest-env"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# pytest.ini\n",
+    "[pytest]\n",
+    "env =\n",
+    "    API_KEY=example-key\n",
+    "    API_ENDPOINT=https://example.endpoint.net\n",
+    "    \n",
+    "# test_example.py\n",
+    "import os\n",
+    "\n",
+    "def test_load_env_vars():\n",
+    "    assert os.environ[\"API_KEY\"] == \"example-key\"\n",
+    "    assert os.environ[\"API_ENDPOINT\"] == https://example.endpoint.net\""
+   ]
   }
  ],
  "metadata": {