yaml564 B

YAML Null and Empty Values

Five spellings of null against the things routinely confused with it: empty strings, empty collections, and a key written with no value at all. Includes a sequence containing a hole, an empty string and two nulls in a row.

Config parsing Encoding detection Editor testing

Preview, first 29 linesyaml

# Null and empty. YAML has several spellings of null and several things that are NOT null but
# are frequently confused with it. A config loader that treats them alike will happily accept a
# key it should have rejected.
explicit_null: null
tilde_null: ~
implicit_null:
upper_null: NULL
title_null: Null
tilde_in_string: "~"

empty_string: ""
empty_single_quoted: ''
empty_map: {}
empty_list: []

list_with_holes:
  - first
  -
  - ""
  - null
  - ~

map_with_empty_values:
  a:
  b: ""
  c: {}

after_empty_value: this key proves the empty value above terminated

Specifications

Null Spellings: 5
Empty Collections: 2
Empty Strings: 2
Edge Case: an omitted value is null, not an empty string

Testing contract

Expected to pass

Scenario: Distinguish YAML null from an empty string and from an empty collection
Expected result: implicit_null, explicit_null, tilde_null, upper_null and title_null all load as null, while empty_string, empty_map and empty_list load as distinct non-null values

What is a .yaml file?

YAML (YAML Ain't Markup Language) is a human-readable data-serialization format using indentation, key-value pairs, and lists, and is a superset of JSON. It supports comments, anchors, and multiple documents per file, favoring readability for configuration. Its indentation sensitivity makes it error-prone to hand-edit.

How to use this file

Use an example YAML file to test config parsers, indentation and anchor handling, multi-document streams, and safe-loading to avoid arbitrary object construction.

How to use this file for testing

“YAML Null and Empty Values” is a deterministic Testaroo fixture for Config parsing, Encoding detection, Editor testing. TOML and INI configuration files with nested sections and typed values, for testing config parsers and loaders.

Documented properties for this file: YAML · 564 bytes. Compare results against paired or grouped companions on this page when present (clean↔damaged, searchable↔scanned, or format twins) so scores stay reproducible across runs.

Download the file once, keep the path stable in CI or local scripts, and treat the spec table as the contract: dimensions, seeds, field lists, and roles are intentional. Corrupt or invalid samples are labelled as such, expect parsers to fail loudly rather than silently accept them.

Pipeline and infrastructure fixtures are inert configuration: steps reference fictional images and scripts, and nothing here executes. Run your linter, schema validator, migrator, or policy engine against them, and expect the deprecated-syntax and intentionally invalid variants to be rejected.

Point your config loader at the file and assert it reads the documented sections and typed values, including any deliberately-tricky nesting or comments.

Code examples

import yaml  # pip install pyyaml

with open("null-and-empty.yaml") as f:
    data = yaml.safe_load(f)
print(data)

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