Creating files

Creation of specific file formats is extensively covered in dedicated sections:

This section covers basic concepts of file generation within fake.py.

Basics

It’s possible to generate either in-memory byte content or actual files on the file system.

  • When generating bytes, the returned value is BytesValue.

  • When generating files on the file system, the returned value is StringValue.

Both BytesValue and StringValue behave like bytes and str respectively, but have a data (dict) property, which contains useful meta-data about the specific kind of file.

For generated files, it will always have the following:

  • storage: Storage class that was used to generate the file.

  • filename: Absolute file path. It’s important to know that string representation of the file contains a relative file path.

See the example below for a graphic PDF generation:

from fake import FAKER

pdf_file = FAKER.pdf_file()

print(pdf_file)  # Relative path
# tmp/tmpnvwoa2ap.pdf

print(pdf_file.data["filename"])  # Absolute path
# /tmp/tmp/tmpnvwoa2ap.pdf

print(pdf_file.data)  # Meta-data
# {'storage': <fake.FileSystemStorage at 0x7f72221fd750>,
#  'filename': '/tmp/tmp/tmpragc8wyr.pdf',
#  'content': None}

See the example below for a text PDF generation:

from fake import FAKER

pdf_file = FAKER.text_pdf_file()

print(pdf_file)
# tmp/tmpragc8wyr.pdf

print(pdf_file.data["filename"])
# /tmp/tmp/tmpragc8wyr.pdf

print(pdf_file.data)
# {'storage': <fake.FileSystemStorage at 0x7f7222157750>,
#  'filename': '/tmp/tmp/tmpragc8wyr.pdf',
#  'content': 'If dutch beats although complex.'}

Note, that text PDF does contain full text of the entire document in the content key.

You can create custom file types using generic_file. Here’s an example for creating an XML file:

from fake import FAKER, FILE_REGISTRY, StringTemplate

xml_content = StringTemplate(
    "<article><title>{sentence(nb_words=5)}</title></article>"
)

xml_file = FAKER.generic_file(
    content=xml_content,
    extension="xml",
)

assert xml_file
assert str(xml_file).endswith(".xml")
FILE_REGISTRY.clean_up()

You can also use LazyStringTemplate if you need the content to be regenerated on each access.

Clean up files

FileSystemStorage is the default storage and by default files are stored inside a tmp directory within the system’s temporary directory, which is commonly cleaned up after system restart. However, there’s a mechanism of cleaning up files after the tests run. At any time, to clean up all files created by that moment, call clean_up method of the FileRegistry class instance, as shown below:

from fake import FAKER, FILE_REGISTRY  # Import the file registry

# Create a file
txt_file = FAKER.txt_file()  # type: ``StringValue``
filename = str(txt_file)  # Relative path to the file
storage = txt_file.data["storage"]  # Storage instance

# File should exist
assert storage.exists(filename)

# Trigger the clean-up
FILE_REGISTRY.clean_up()

# File no longer exists
assert storage.exists(filename) is False

Typically you would call the clean_up method in the tearDown.

To remove a single file, use the remove method of FileRegistry instance. In the example below, the file is removed by providing the StringValue instance:

from fake import FAKER, FILE_REGISTRY

# Create a file
txt_file = FAKER.txt_file()  # type: StringValue
filename = str(txt_file)  # Relative path to the file
storage = txt_file.data["storage"]  # Storage instance

# File should exist
assert storage.exists(filename)

# Remove the file by providing the ``StringValue`` instance
FILE_REGISTRY.remove(txt_file)

# File no longer exists
assert storage.exists(filename) is False

You can also remove by path. In the exampl below, the file is removed by providing the str instance:

from fake import FAKER, FILE_REGISTRY

# Create a file
txt_file = FAKER.txt_file()  # type: StringValue
filename = str(txt_file)  # Relative path to the file
storage = txt_file.data["storage"]  # Storage instance

# File should exist
assert storage.exists(filename)

# Remove the file by providing the ``filename``
FILE_REGISTRY.remove(filename)

# File no longer exist
assert storage.exists(filename) is False

If you only have a path to the file as str instance, you can find the correspondent StringValue instance by searching, using the search method:

 
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