== MIME types ==

resources/mime-types.json and resources/generated-mime-types.json contain MIME type tests. The tests are encoded as a JSON array. String values in the array serve as documentation. All other values are objects with the following fields:

• input: The string to be parsed.
• output: Null if parsing resulted in failure and the MIME type record serialized as string otherwise.
• navigable: True if the MIME type can be used for a document to be loaded in a browsing context (i.e., does not result in a download) and omitted otherwise.
• encoding: The encoding that can be extracted from the MIME type or null if no encoding can be extracted, and omitted otherwise.

Note: the object description implies that there tests without navigable or encoding set.

A wrapper for these JSON MIME type tests needs to take care that not all input values can be tested in all entrypoints. Some entrypoints only accept bytes and some have further restrictions. A function such as the one below can be used to differentiate:

function isByteCompatible(str) {
  for(let i = 0; i < str.length; i++) {
    const charCode = str.charCodeAt(i);
    // See https://fetch.spec.whatwg.org/#concept-header-value
    if(charCode > 0xFF) {
      return "incompatible";
    } else if(charCode === 0x00 || charCode === 0x0A || charCode === 0x0D) {
      return "header-value-incompatible";
    }
  }
  return "compatible";
}

resources/generated-mime-types.json is generated by running resources/generated-mime-types.py. Modify the latter to correct the former.

These tests are used by resources in this directory to test various aspects of MIME types.