These examples show how to build stories that rewrite themselves from program output (in-test snapshot testing). This can be done with

self.current_step.rewrite("argument").to("new output")

Code Example

example.story:

Append text to file:
  steps:
    - Run: echo hello >> mytext.txt
    - Run: echo hello >> mytext.txt
    - Run: echo hello >> mytext.txt

  variations:
    Output text to:
      following steps:
        - Run and get output:
            command: cat mytext.txt
            will output: old value

engine.py:

from hitchstory import BaseEngine

class Engine(BaseEngine):
    def __init__(self, rewrite=True):
        self._rewrite = rewrite

    def run(self, command):
        pass

    def run_and_get_output(self, command, will_output):
        if self._rewrite:
            self.current_step.rewrite("will_output").to("hello\nhello")

With code:

from hitchstory import StoryCollection
from pathlib import Path
from engine import Engine

Story is rewritten when rewrite=True is used

StoryCollection(Path(".").glob("*.story"), Engine(rewrite=True)).ordered_by_name().play()

Will output:

RUNNING Append text to file in /path/to/working/example.story ... SUCCESS in 0.1 seconds.
RUNNING Append text to file/Output text to in /path/to/working/example.story ... SUCCESS in 0.1 seconds.

File example.story should now contain:

Append text to file:
  steps:
  - Run: echo hello >> mytext.txt
  - Run: echo hello >> mytext.txt
  - Run: echo hello >> mytext.txt

  variations:
    Output text to:
      following steps:
      - Run and get output:
          command: cat mytext.txt
          will output: |-
            hello
            hello

Story remains unchanged when rewrite=False is used instead

StoryCollection(Path(".").glob("*.story"), Engine(rewrite=False)).ordered_by_name().play()

Will output:

RUNNING Append text to file in /path/to/working/example.story ... SUCCESS in 0.1 seconds.
RUNNING Append text to file/Output text to in /path/to/working/example.story ... SUCCESS in 0.1 seconds.

Then the example story will be unchanged.

Executable specification

Documentation automatically generated from rewrite-story.story storytests.