30 file formats, every one generated at an exact size

Each of these is a real file of that format. It opens in the software that owns it, and it is exactly the number of bytes you asked for. None of them is padded zeros with an extension bolted on.

Format	Name	Extension	Smallest file	Fidelity	Checked against
`avif`	AV1 Image File Format	`.avif`	311	full	pillow
`bmp`	Windows Bitmap	`.bmp`	58	full	pillow
`csv`	Comma-Separated Values	`.csv`	115	full	python-csv
`docx`	Word (Office Open XML)	`.docx`	1220	full	libreoffice
`eml`	Email message	`.eml`	289	full	python-email
`geojson`	GeoJSON	`.geojson`	875	full	gdal-geojson
`gif`	Graphics Interchange Format	`.gif`	114	full	pillow
`html`	HyperText Markup Language	`.html`	118	full	python-html
`ico`	Windows Icon	`.ico`	70	full	pillow
`jpg`	JPEG	`.jpg`	602	full	pillow
`json`	JavaScript Object Notation	`.json`	219	full	node-json
`jxl`	JPEG XL	`.jxl`	147	full	pillow-jxl
`log`	Server and application log	`.log`	155	full	not applicable
`md`	Markdown	`.md`	0	full	not applicable
`mp4`	MP4 video	`.mp4`	3312	full	libaom
`pdf`	Portable Document Format	`.pdf`	3415	full	pdftotext
`png`	Portable Network Graphics	`.png`	74	full	pillow
`pptx`	PowerPoint (Office Open XML)	`.pptx`	4809	full	libreoffice
`svg`	Scalable Vector Graphics	`.svg`	194	full	inkscape
`targz`	tar + gzip	`.tar.gz`	9790	full	7z
`tiff`	Tagged Image File Format	`.tiff`	183	full	pillow
`toml`	TOML	`.toml`	212	full	python-toml
`txt`	Plain text	`.txt`	0	full	not applicable
`wav`	Waveform Audio	`.wav`	98	full	ffprobe
`webm`	WebM video	`.webm`	3284	full	libaom
`webp`	WebP	`.webp`	148	full	pillow
`xlsx`	Excel (Office Open XML)	`.xlsx`	1726	full	libreoffice
`xml`	Extensible Markup Language	`.xml`	264	full	python-xml
`yaml`	YAML	`.yaml`	241	full	python-yaml
`zip`	ZIP	`.zip`	8382	full	7z

What the columns mean

Smallest file

The fewest bytes this tool will accept for that format, including the label it writes inside the file. Ask for less and you get an error naming the floor and the reason for it, never a file of the wrong size.
Fidelity

How complete the file is. full means a reader that really parses the format accepts it, not merely that the extension matches.
Checked against

The independent reader that opens every generated file before the format ships - a separate implementation, not our own code marking its own homework.

Every format also repeats to the byte: the same recipe and seed produce identical files on any machine, which is what makes a recipe safe to commit in place of the fixtures themselves.

Settings each format accepts

Most formats take settings of their own - image dimensions, JPEG quality, PDF page count, rows and columns in a spreadsheet, how many entries go inside an archive. Set them with --set key=value on the command line, or under properties: in a recipe.

tfg generate --format jpg --size 500kb --set width=1920 --set height=1080 --set quality=85

Format	Setting	Accepts
`avif`	`width`	1 - 16384 pixels
	`height`	1 - 16384 pixels
	`quality`	1 - 100
`bmp`	`width`	1 - 20000 pixels
	`height`	1 - 20000 pixels
`csv`	`delimiter`	comma, pipe, semicolon, tab
	`line_ending`	crlf, lf
	`header`	true or false
	`quote_style`	all, minimal, none
	`columns`	2 - 32768 columns
`docx`	`paragraphs`	1 - 50000 paragraphs
`eml`	`body`	alternative, html, plain
	`text_encoding`	7bit, 8bit, quoted-printable
	`headers`	ascii, encoded, utf8
	`line_endings`	crlf, lf
	`attachments`	0 - 10000
	`attachment_format`	the id of a format, as tfg formats lists them
	`attachment_size`	a size such as 2mb
	`filename_style`	both, content-type, rfc2047, rfc2231
`geojson`	`geometry`	geometrycollection, linestring, mixed, multilinestring, multipoint, multipolygon, point, polygon
	`formatting`	indented, minified, record-per-line
	`precision`	0 - 15 decimal places
	`altitude`	true or false
	`vertices`	3 - 1000000 points
	`holes`	0 - 100000 holes
	`winding`	reversed, rfc7946
	`antimeridian`	true or false
	`unlocated`	all, none, some
	`ids`	mixed, none, number, string
	`bbox`	true or false
`gif`	`width`	1 - 20000 pixels
	`height`	1 - 20000 pixels
	`frames`	1 - 60
`html`	`structure`	document, fragment
`ico`	`width`	1 - 256 pixels
	`height`	1 - 256 pixels
	`embed`	bmp, png
`jpg`	`width`	1 - 20000 pixels
	`height`	1 - 20000 pixels
	`quality`	1 - 100
`json`	`formatting`	indented, minified, record-per-line
`jxl`	`width`	1 - 16384 pixels
	`height`	1 - 16384 pixels
	`quality`	1 - 100
`log`	`entry_format`	apache-combined, apache-common, json-lines, nginx, plain, syslog
	`timestamps`	advancing, fixed
	`rate`	1 - 1000000 entries per second
	`methods`	get, mixed, read
	`status_mix`	client-errors, realistic, server-errors, success
	`level_mix`	debug, errors, quiet, realistic
	`ip_version`	mixed, v4, v6
	`line_ending`	crlf, lf
`md`	`encoding`	utf-16be, utf-16le, utf-8
	`bom`	true or false
`mp4`	`width`	1 - 16384 pixels
	`height`	1 - 16384 pixels
	`duration`	a length of time such as 10s
	`change_interval`	a length of time such as 10s
	`frame_rate`	1, 5, 10, 12, 15, 24, 25, 30, 48, 50, 60
	`keyframe_interval`	a length of time such as 10s
	`quality`	1 - 100
`pdf`	`pages`	1 - 5000
	`page_size`	a3, a4, a5, legal, letter, mixed
	`orientation`	landscape, mixed, portrait
	`rotate`	0, 90, 180, 270
	`pdf_version`	1.4, 1.7
	`title`	any text
	`author`	any text
	`subject`	any text
	`keywords`	any text
	`creator`	any text
	`producer`	any text
	`created`	a date such as 2024-02-29 or 2024-02-29T13:45:00+02:00, or none
	`modified`	a date such as 2024-02-29 or 2024-02-29T13:45:00+02:00, or none
`png`	`width`	1 - 20000 pixels
	`height`	1 - 20000 pixels
`pptx`	`slides`	1 - 500 slides
`svg`	`width`	1 - 20000 pixels
	`height`	1 - 20000 pixels
`targz`	`entries`	0 - 10000
	`entry_format`	the id of a format, as tfg formats lists them
	`entry_size`	a size such as 2mb
	`compression`	best, default, fast, none
	`depth`	0 - 50
	`directory_entries`	true or false
	`entry_mode`	000, 400, 444, 600, 644, 664, 666, 700, 755, 777
	`entry_owner`	root, unset, user
`tiff`	`width`	1 - 20000 pixels
	`height`	1 - 20000 pixels
`txt`	`encoding`	utf-16be, utf-16le, utf-8
	`bom`	true or false
`wav`	`sample_rate`	8000 - 192000 hertz
	`bit_depth`	8, 16, 24, 32
	`channels`	1 - 8
	`content`	noise, silence, sweep, tone
`webm`	`width`	1 - 16384 pixels
	`height`	1 - 16384 pixels
	`duration`	a length of time such as 10s
	`change_interval`	a length of time such as 10s
	`frame_rate`	1, 5, 10, 12, 15, 24, 25, 30, 48, 50, 60
	`keyframe_interval`	a length of time such as 10s
	`quality`	1 - 100
`webp`	`width`	1 - 16383 pixels
	`height`	1 - 16383 pixels
`xlsx`	`rows`	1 - 200000 rows
	`columns`	1 - 32768 columns
`xml`	`encoding`	utf-16be, utf-16le, utf-8
	`bom`	true or false
`zip`	`entries`	0 - 10000
	`entry_format`	the id of a format, as tfg formats lists them
	`entry_size`	a size such as 2mb
	`compression`	best, default, fast, none
	`depth`	0 - 50
	`directory_entries`	true or false
	`password`	the password, in plain text
	`encryption`	aes-128, aes-192, aes-256, none, zipcrypto

A value outside what a setting accepts is refused with a message naming the setting, the allowed range and what to use instead. An unknown setting is an error too, never a silent default - a typo accepted in silence gives a file with the wrong settings and an hour spent wondering why the test passes when it should not.

Run tfg formats <id> to see exactly what one format accepts on the build you have.

Archives hold real files

eml and targz and zip can be filled with entries rather than left as an empty shell. A generated archive genuinely contains the documents it claims to contain, so anything that unpacks it during a test finds real files inside.

targets:
  - id: bundle
    format: zip
    contains:
      - format: txt
        count: 200
        size: 4kb