FastAPI Development - Cooking Python in Emacs

Preface
Prerequisites
- A separate venv
- Install FastAPI
A Primitive App
Manual testing
Enter uinttest

Preface

Emacs text editor is powerful enough to simplify the task of FastAPI development by providing its faculties inside Org-mode Babel Python code blocks.

Prerequisites

A separate venv

pyvenv-create
pyvenv-activate

Install `FastAPI`

pip list

Package    Version
---------- -------
pip        23.0.1
setuptools 66.1.1
wheel      0.38.4

pip install fastapi

Collecting fastapi
  Downloading fastapi-0.111.1-py3-none-any.whl (92 kB)
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Collecting starlette<0.38.0,>=0.37.2
  Downloading starlette-0.37.2-py3-none-any.whl (71 kB)
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Collecting pydantic!=1.8,!=1.8.1,!=2.0.0,!=2.0.1,!=2.1.0,<3.0.0,>=1.7.4
  Using cached pydantic-2.8.2-py3-none-any.whl (423 kB)
Collecting typing-extensions>=4.8.0
  Using cached typing_extensions-4.12.2-py3-none-any.whl (37 kB)
Collecting fastapi-cli>=0.0.2
  Downloading fastapi_cli-0.0.4-py3-none-any.whl (9.5 kB)
Collecting httpx>=0.23.0
  Using cached httpx-0.27.0-py3-none-any.whl (75 kB)
Collecting jinja2>=2.11.2
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Collecting python-multipart>=0.0.7
  Downloading python_multipart-0.0.9-py3-none-any.whl (22 kB)
Collecting email_validator>=2.0.0
  Downloading email_validator-2.2.0-py3-none-any.whl (33 kB)
Collecting uvicorn[standard]>=0.12.0
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Collecting dnspython>=2.0.0
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Collecting idna>=2.0.0
  Using cached idna-3.7-py3-none-any.whl (66 kB)
Collecting typer>=0.12.3
  Downloading typer-0.12.3-py3-none-any.whl (47 kB)
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Collecting anyio
  Using cached anyio-4.4.0-py3-none-any.whl (86 kB)
Collecting certifi
  Using cached certifi-2024.7.4-py3-none-any.whl (162 kB)
Collecting httpcore==1.*
  Using cached httpcore-1.0.5-py3-none-any.whl (77 kB)
Collecting sniffio
  Using cached sniffio-1.3.1-py3-none-any.whl (10 kB)
Collecting h11<0.15,>=0.13
  Using cached h11-0.14.0-py3-none-any.whl (58 kB)
Collecting MarkupSafe>=2.0
  Downloading MarkupSafe-2.1.5-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (28 kB)
Collecting annotated-types>=0.4.0
  Using cached annotated_types-0.7.0-py3-none-any.whl (13 kB)
Collecting pydantic-core==2.20.1
  Using cached pydantic_core-2.20.1-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (2.1 MB)
Collecting click>=7.0
  Downloading click-8.1.7-py3-none-any.whl (97 kB)
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Collecting httptools>=0.5.0
  Downloading httptools-0.6.1-cp311-cp311-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_17_x86_64.manylinux2014_x86_64.whl (318 kB)
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Collecting python-dotenv>=0.13
  Downloading python_dotenv-1.0.1-py3-none-any.whl (19 kB)
Collecting pyyaml>=5.1
  Downloading PyYAML-6.0.1-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (757 kB)
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Collecting uvloop!=0.15.0,!=0.15.1,>=0.14.0
  Downloading uvloop-0.19.0-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (3.5 MB)
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Collecting watchfiles>=0.13
  Downloading watchfiles-0.22.0-cp311-cp311-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (1.2 MB)
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Collecting websockets>=10.4
  Downloading websockets-12.0-cp311-cp311-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_17_x86_64.manylinux2014_x86_64.whl (130 kB)
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Collecting shellingham>=1.3.0
  Downloading shellingham-1.5.4-py2.py3-none-any.whl (9.8 kB)
Collecting rich>=10.11.0
  Downloading rich-13.7.1-py3-none-any.whl (240 kB)
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Collecting markdown-it-py>=2.2.0
  Downloading markdown_it_py-3.0.0-py3-none-any.whl (87 kB)
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Collecting pygments<3.0.0,>=2.13.0
  Downloading pygments-2.18.0-py3-none-any.whl (1.2 MB)
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Collecting mdurl~=0.1
  Downloading mdurl-0.1.2-py3-none-any.whl (10.0 kB)
Installing collected packages: websockets, uvloop, typing-extensions, sniffio, shellingham, pyyaml, python-multipart, python-dotenv, pygments, mdurl, MarkupSafe, idna, httptools, h11, dnspython, click, certifi, annotated-types, uvicorn, pydantic-core, markdown-it-py, jinja2, httpcore, email_validator, anyio, watchfiles, starlette, rich, pydantic, httpx, typer, fastapi-cli, fastapi
Successfully installed MarkupSafe-2.1.5 annotated-types-0.7.0 anyio-4.4.0 certifi-2024.7.4 click-8.1.7 dnspython-2.6.1 email_validator-2.2.0 fastapi-0.111.1 fastapi-cli-0.0.4 h11-0.14.0 httpcore-1.0.5 httptools-0.6.1 httpx-0.27.0 idna-3.7 jinja2-3.1.4 markdown-it-py-3.0.0 mdurl-0.1.2 pydantic-2.8.2 pydantic-core-2.20.1 pygments-2.18.0 python-dotenv-1.0.1 python-multipart-0.0.9 pyyaml-6.0.1 rich-13.7.1 shellingham-1.5.4 sniffio-1.3.1 starlette-0.37.2 typer-0.12.3 typing-extensions-4.12.2 uvicorn-0.30.1 uvloop-0.19.0 watchfiles-0.22.0 websockets-12.0

pip list


Package           Version
----------------- --------
annotated-types   0.7.0
anyio             4.4.0
certifi           2024.7.4
click             8.1.7
dnspython         2.6.1
email_validator   2.2.0
fastapi           0.111.1
fastapi-cli       0.0.4
h11               0.14.0
httpcore          1.0.5
httptools         0.6.1
httpx             0.27.0
idna              3.7
Jinja2            3.1.4
markdown-it-py    3.0.0
MarkupSafe        2.1.5
mdurl             0.1.2
pip               23.0.1
pydantic          2.8.2
pydantic_core     2.20.1
Pygments          2.18.0
python-dotenv     1.0.1
python-multipart  0.0.9
PyYAML            6.0.1
rich              13.7.1
setuptools        66.1.1
shellingham       1.5.4
sniffio           1.3.1
starlette         0.37.2
typer             0.12.3
typing_extensions 4.12.2
uvicorn           0.30.1
uvloop            0.19.0
watchfiles        0.22.0
websockets        12.0
wheel             0.38.4

A Primitive App

from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}

Manual testing

As it is explained in your browser.

Enter `uinttest`

I wrote a primitive FastAPI app:

from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}

can you write the unittest for it?

Certainly! To write `unittest` tests for your FastAPI application, we
can use the `TestClient` provided by FastAPI which is a wrapper around
Starlette's `TestClient`. This allows us to simulate HTTP requests to
our endpoints and verify their responses.

Below is how you can structure your unit tests using the `unittest`
module:

FastAPI Application

from typing import Union
from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def read_root():
    return {"Hello": "World"}

@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}

Unit Tests

import unittest
from fastapi.testclient import TestClient
from code.awesomeapp.main import app  # Assuming your FastAPI app is saved in main.py

client = TestClient(app)

class TestFastAPI(unittest.TestCase):

    def test_read_root(self):
        response = client.get("/")
        self.assertEqual(response.status_code, 200)
        self.assertDictEqual(response.json(), {"Hello": "World"})

    def test_read_item_with_query(self):
        response = client.get("/items/42?q=somequery")
        self.assertEqual(response.status_code, 200)
        self.assertDictEqual(response.json(), {"item_id": 42, "q": "somequery"})
    
    def test_read_item_without_query(self):
        response = client.get("/items/42")
        self.assertEqual(response.status_code, 200)
        self.assertDictEqual(response.json(), {"item_id": 42, "q": None})

if __name__ == "__main__":
    unittest.main()

...
----------------------------------------------------------------------
Ran 3 tests in 0.014s

OK

Explanation

Importing FastAPI App:
- Import the FastAPI app instance from the file where it is defined (main in this case).
Test Client:
- Create an instance of TestClient, passing in the FastAPI app object. This client will be used to make requests to the endpoints for testing.
Unit Test Class:
- Define a class TestFastAPI that inherits from unittest.TestCase. This class will contain all our test methods.
Test Methods:
- test_read_root:
  - This method tests the root endpoint /. We expect a 200 status code and a JSON response {"Hello": "World"}.
- test_read_item_with_query:
  - This method tests the /items/{item_id} endpoint with an additional query parameter q. We expect a 200 status code and a JSON response containing the item ID and the query parameter.
- test_read_item_without_query:
  - This method tests the /items/{item_id} endpoint without the query parameter q. We expect a 200 status code and a JSON response containing the item ID with q as None.

Running the Tests

To run the tests, you can:

Save the application code in main.py.
Save the test code in a separate file, e.g., test_main.py.

Execute the tests using the unittest command in your terminal:

cd code/awesomeapp/
python -m unittest test_main.py


...
----------------------------------------------------------------------
Ran 3 tests in 0.015s

OK

Alternatively, if you're working within Emacs with Org-mode and Babel, you can execute the test code block within the Org document.

This setup will help you ensure that your FastAPI application works as expected.

FastAPI Development environment set up

Table of Contents

Preface

Prerequisites

A separate venv

Install `FastAPI`

A Primitive App

Manual testing

Enter `uinttest`

FastAPI Application

Unit Tests

Explanation

Running the Tests

FastAPI Development environment set up

Table of Contents

Preface

Prerequisites

A separate venv

Install FastAPI

A Primitive App

Manual testing

Enter uinttest

FastAPI Application

Unit Tests

Explanation

Running the Tests

Install `FastAPI`

Enter `uinttest`