Skip to content
gherkin-cli

TOON format

TOON is a compact, whitespace-structured text encoding — the default output format for every gherkin-cli command, per the AXI output contract. It renders the same data as JSON in far fewer tokens by collapsing arrays of uniform objects into a tabular block instead of repeating each key per row.

Encoding rules

Section titled “Encoding rules”
  • Scalars render as key: value. Strings carrying a comma, colon, whitespace, or bracket are quoted; null/undefined render as null.
  • Inline scalar arrays render as key: [a,b,c] on one line.
  • Uniform object arrays (every item has only scalar or scalar-array fields) render as a tabular block: a header naming the length and the column union, then one comma-joined row per item — no repeated keys.
  • Nested object arrays (an item field is itself an object) render as a key[N]: list of indented, - -prefixed blocks instead of a table, since the shape isn’t uniform enough to tabulate.
  • Nested plain objects render as key: followed by an indented block.

Example

Section titled “Example”

Given this data (the shape parse emits):

{
  "summary": { "files": 1, "scenarios": 2, "errors": 0 },
  "files": [
    {
      "file": "a.feature",
      "featureTags": ["@auth"],
      "scenarioCount": 2,
      "scenarios": [
        { "name": "Successful login", "keyword": "Scenario", "tags": ["@smoke"] },
        { "name": "Failed login", "keyword": "Scenario", "tags": [] }
      ]
    }
  ]
}

gherkin-cli renders it as:

summary:
  files: 1
  scenarios: 2
  errors: 0
files[1]:
  - file: a.feature
    featureTags: [@auth]
    scenarioCount: 2
    scenarios[2]{name,keyword,tags}:
      "Successful login",Scenario,[@smoke]
      "Failed login",Scenario,[]

Every scenarios row is uniform (name, keyword, tags), so it tabulates into one header plus two comma-joined rows — no repeated field names, unlike the equivalent JSON.

Truncation

Section titled “Truncation”

A rendered TOON result longer than 50 lines is truncated with a size hint (… +N lines — rerun with --full) unless --full is passed. --format json output is never truncated — it is the explicit escape hatch for a caller that wants the whole payload regardless of size.

See also

Section titled “See also”