A pytest plugin to parametrize tests by CSV files.
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pytest-csv-params/README.md

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pytest-csv-params

pytest-csv-params

A pytest plugin to parametrize data-driven tests by CSV files.

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Requirements

  • Python 3.8, 3.9 or 3.10
  • pytest >= 7.1

There's no operating system dependent code in this plugin, so it should run anywhere where pytest runs.

Installation

Simply install it with pip...

pip install pytest-csv-params

... or poetry ...

poetry add --dev pytest-csv-params

Documentation / User Guide

Detailed documentation can be found under docs.codebau.dev/pytest-plugins/pytest-csv-params/

Usage: Command Line Argument

Argument Required Description Example
--csv-params-base-dir no (optional) Define a base dir for all relative-path CSV data files (since 0.1.0) pytest --csv-params-base-dir /var/testdata

Usage: Decorator

Simply decorate your test method with @csv_params (pytest_csv_params.decorator.csv_params) and the following parameters:

Parameter Type Description Example
data_file str The CSV file to use, relative or absolute path "/var/testdata/test1.csv"
base_dir str (optional) Directory to look up relative CSV files (see data_file); overrides the command line argument join(dirname(__file__), "assets")
id_col str (optional) Column name of the CSV that contains test case IDs "ID#"
dialect csv.Dialect (optional) CSV Dialect definition (see Python CSV Documentation) csv.excel_tab
data_casts dict (optional) Cast Methods for the CSV Data (see "Data Casting" below) { "a": int, "b": float }
header_renames dict (optional) Replace headers from the CSV file, so that they can be used as parameters for the test function (since 0.3.0) { "Annual Amount of Bananas": "banana_count", "Cherry export price": "cherry_export_price" }

CSV Format

The default CSV format is:

  • \r\n as line ending
  • All non-numeric fields are surrounded by "
  • If you need a " in the value, use "" (double quote)
  • Fields are separated by comma (,)

Usage Example

This example uses the CSV example from above.

from pytest_csv_params.decorator import csv_params

@csv_params(
    data_file="/data/test-lib/cases/addition.csv",
    id_col="ID#",
    data_casts={
        "part_a": int,
        "part_b": int,
        "expected_result": int,
    },
)
def test_addition(part_a, part_b, expected_result):
    assert part_a + part_b == expected_result

Shorthand example (no ID col, only string values):

from pytest_csv_params.decorator import csv_params

@csv_params("/data/test-lib/cases/texts.csv")
def test_texts(text_a, text_b, text_c):
    assert f"{text_a}:{text_b}" == text_c

More complex example

This example features nearly all things the plugin has to offer. You find this example also in the test cases, see tests/test_complex_example.py.

The CSV file (tests/assets/example.csv):

"Test ID","Bananas shipped","Single Banana Weight","Apples shipped","Single Apple Weight","Container Size"
"Order-7","1503","0.5","2545","0.25","1500"
"Order-15","101","0.55","1474","0.33","550"

The Test (tests/test_complex_example.py):

from math import ceil
from os.path import join, dirname

from pytest_csv_params.decorator import csv_params


@csv_params(
    data_file="example.csv",
    base_dir=join(dirname(__file__), "assets"),
    id_col="Test ID",
    header_renames={
        "Bananas shipped": "bananas_shipped",
        "Single Banana Weight": "banana_weight",
        "Apples shipped": "apples_shipped",
        "Single Apple Weight": "apple_weight",
        "Container Size": "container_size",
    },
    data_casts={
        "bananas_shipped": int,
        "banana_weight": float,
        "apples_shipped": int,
        "apple_weight": float,
        "container_size": int,
    },
)
def test_container_size_is_big_enough(
    bananas_shipped: int, banana_weight: float, apples_shipped: int, apple_weight: float, container_size: int
) -> None:
    """
    This is just an example test case for the documentation.
    """

    gross_weight = (banana_weight * bananas_shipped) + (apple_weight * apples_shipped)
    assert ceil(gross_weight) <= container_size

If you decide not to rename the columns, the test would look like this:

@csv_params(
    data_file="example.csv",
    base_dir=join(dirname(__file__), "assets"),
    id_col="Test ID",
    data_casts={
        "Bananas_Shipped": int,
        "Single_Banana_Weight": float,
        "Apples_Shipped": int,
        "Single_Apple_Weight": float,
        "Container_Size": int,
    },
)
def test_container_size_is_big_enough(
    Bananas_Shipped: int, Single_Banana_Weight: float, Apples_Shipped: int, Single_Apple_Weight: float, Container_Size: int
) -> None:
    ...

Changelog

Bugs etc.

Please send your issues to csv-params_issues (at) jued.de. Please include the following:

  • Plugin Version used
  • Pytest version
  • Python version with operating system

It would be great if you could include example code that clarifies your issue.

See CONTRIBUTING.md for details.

Pull Requests

Pull requests are always welcome. Since this Gitea instance is not open to public, just send an e-mail to discuss options.

Any changes that are made are to be backed by tests. Please give me a sign if you're going to break the existing API and let us discuss ways to handle that.

See CONTRIBUTING.md for details.

Where are the sources?

The source code is available under git.codebau.dev/pytest-plugins/pytest-csv-params.