IO Module

The IO module provides steps for file, JSON, CSV and directory operations. It covers file CRUD, file assertions, JSON key-path navigation and validation, CSV writing and reading, directory management, and reading files as lines — 38 steps in total, all with es and pt translations.

Installation

The IO module uses only the Python standard library (json, csv, pathlib). JSON Schema validation requires the jsonschema package:

pip install "behave-steplib[io]"

No extra is needed for basic file, JSON, CSV and directory operations — the IO module is always available when steplib is installed. Install the [io] extra to enable JSON Schema validation.

Context

The IOContext lives at context.steplib.io. It holds:

• variables — a dict[str, Any] for user-defined variables.

• _last_json — the last loaded JSON object for key-path-based assertions.

• _csv_writer / _csv_file — active CSV writer and file handle.

def before_all(context):
    context.steplib = autoload(context)

def before_scenario(context, scenario):
    context.steplib.reset()  # clears variables, closes CSV handles

def after_scenario(context, scenario):
    context.steplib.cleanup()  # closes any open file handles

Steps

File operations

Pattern	Description
I read the file {path} into {variable}	Read a text file and store its content as a variable.
I read the file {path} as lines into {variable}	Read a file and store its lines as a list in a variable.
I write {content} to the file {path}	Write content to a file (overwrites existing).
I append {content} to the file {path}	Append content to a file.
I delete the file {path}	Delete a file.
I copy the file {source} to {destination}	Copy a file to a new location.
I move the file {source} to {destination}	Move a file to a new location.
I rename the file {path} to {new_path}	Rename a file.
I create an empty file at {path}	Create an empty file.

File assertions

Pattern	Description
the file {path} exists	Assert that a file exists.
the file {path} does not exist	Assert that a file does not exist.
the files {path1} and {path2} are the same	Assert that two files have identical content.
I get the size of the file {path} as {variable}	Store a file’s size in bytes as a variable.
I get the extension of the file {path} as {variable}	Store a file’s extension as a variable.

Directory operations

Pattern	Description
I create the directory {path}	Create a directory, including parents if needed.
the directory {path} exists	Assert that a directory exists.
the directory {path} does not exist	Assert that a directory does not exist.
I list the files in the directory {path} as {variable}	List files in a directory and store them as a variable.
I delete the directory {path}	Delete a directory and all its contents.

JSON operations

JSON key paths use dot notation (user.name, items.0.id) — not the $. JSONPath syntax used by the API module.

Pattern	Description
I load the JSON file {path} as the last JSON	Load a JSON file into the context’s last JSON object.
I save the JSON to the file {path}	Save the last JSON object to a file.
the JSON key path {key_path} equals {value}	Assert that a JSON key path equals a value.
I store the JSON key path {key_path} as {variable}	Store a JSON key path value into a variable.
I update the JSON key path {key_path} to {value}	Update a JSON key path value.
I create the JSON key path {key_path} with value {value}	Create a new JSON key path with a value.
I delete the JSON key path {key_path}	Delete a JSON key path.
the JSON {json_string} is valid	Assert that a JSON string is valid JSON.
the JSON matches the schema {schema_path}	Assert that the last loaded JSON matches a JSON Schema file. Requires the [io] extra (jsonschema).
the last JSON is valid	Assert that the last loaded JSON is valid by re-serializing it.
I get the type of the JSON key path {key_path} as {variable}	Store the type name of a JSON key path value as a variable.
I diff the JSON objects {json1} and {json2}	Diff two JSON objects and store the differences as diff_json.
I merge the JSON {origin_name} into {target_name} with {priority} priority	Merge two stored JSON variables; priority decides which side wins on conflicts (origin or target).

CSV operations

Pattern	Description
I create the CSV file {path} from the data {data}	Create a CSV file from a JSON array of objects (keys become the header row).
I create a CSV writer for file {path} with fieldnames {fieldnames}	Create a CSV writer for incremental writing.
I write the CSV row {row}	Write a row (a JSON object) to the active CSV writer.
I save the CSV file	Flush the active CSV writer to disk without closing it.
I set the header row {row:d} for the CSV file {path} as {variable}	Read a CSV file using a specific row as the header and store the rows in a variable.
I close the CSV writer	Close the active CSV writer and its file handle.

Example

Feature: File and data operations

  Scenario: File CRUD
    Given I create the directory "output/logs"
    When I write "hello world" to the file "output/logs/test.txt"
    Then the file "output/logs/test.txt" exists
    When I read the file "output/logs/test.txt" as lines into "lines"
    Then the variable "lines" has length 1
    When I delete the directory "output"
    Then the directory "output" does not exist

  Scenario: JSON operations
    Given I load the JSON file "data/config.json" as the last JSON
    Then the JSON key path "version" equals "1.0"
    And the JSON matches the schema "schemas/config.json"
    And the last JSON is valid
    When I store the JSON key path "name" as "config_name"
    Then the variable "config_name" equals "myapp"

  Scenario: CSV operations
    When I create the CSV file "output/data.csv" from the data '[{"name":"Alice","age":30}]'
    Given I set the header row 1 for the CSV file "output/data.csv" as "rows"
    Then the variable "rows" has length 1

API reference

See Modules API Reference for the full autodoc reference of the IO module.