A pytest plugin to parametrize tests by CSV files.
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README.md

pytest-csv-params

A pytest plugin to parametrize tests by CSV files.

[:toc:]

Requirements

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

There's no operating system dependend 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

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 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 }

CSV File Lookup Order

CSV files are looked up following this rules:

  • If the data_file parameter is an absolute path, this is used, regardless of the base_dir parameter or command line argument.
  • If the data_file parameter is relative:
    • If the base_dir parameter is set, the file is looked up there, regardless of the command line argument
    • If the base_dir parameter is not set (or None):
      • If the command line argument is set, the file is looked up there
      • If the command line argument is not set, the file is looked up in the current working directory

Data Casting

When data is read from CSV, they are always parsed as str. If you need them in other formats, you can set a method that should be called with the value.

These methods can also be lambdas, and are also good for further transformations.

Data Casting Example

from pytest_csv_params.decorator import csv_params

def normalize(x: str) -> str:
    return x.strip().upper()

@csv_params(
    data_file="/test/data.csv",
    data_casts={
        "col_x": normalize,
        "col_y": float,
    },
)
def test_something(col_x, col_y):
    # Test something...
    ...

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 (,)

Example CSV

"ID#", "part_a", "part_b", "expected_result"
"first", 1, 2, 3
"second", 3, 4, 7
"third", 10, 11, 21

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

Contributing

Build and test

You need Poetry in order to build this project.

Tests are implemented with pytest, and tox is used to orchestrate them for the supported python versions.

  • Checkout this repo
  • Run poetry install
  • Run poetry run tox (for all supported python versions) or poetry run pytest (for your current version)

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.

Pull Requests

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

License

Code is under MIT license. See LICENSE.txt for details.