WIP repo for source map test proof of concept

Running the tests

How to run in Firefox:

• Check out mozilla-unified (see Firefox dev setup under "Setting up your machine" for details, note that you can use git via git-cinnabar)
• cd to the checked out directory.
• Run git am <this-repo>/firefox/0001-WIP-Firefox-source-map-spec-tests.patch
• Run mach build (this builds the test too, you'll need to run it if you modify tests/harness)
• Run mach test devtools/client/shared/source-map-loader/

How to run in WebKit:

• Check out WebKit
• cd to the checked out WebKit directory.
• Run git am <this-repo>/webkit/0001-Add-harness-for-source-maps-spec-tests.patch
• Run Tools/Scripts/build-webkit (depending on the platform you may need to pass --gtk or other flags)
• Run Tools/Scripts/run-webkit-tests LayoutTests/inspector/model/source-map-spec.html (again, you may need --gtk on Linux)

Mozilla source-map library:

• There is a branch for adding the spec tests to the package.

Goals of tests

• Thoroughly test all aspects of the source maps spec that can be tested.
• Strictly follow the spec when determining test behavior.

Test coverage

Core spec

• Encoding
  • Source map must be a valid JSON document.
  • Base64 VLQ
    • VLQs should decode correctly
      • A VLQ with a non-base64 character will fail to decode.
      • A VLQ with one digit and no continuation digits should decode.
      • A negative VLQ with the sign bit set to 1 should decode.
      • A VLQ with non-zero continuation bits (and more than one digit) should decode.
      • A VLQ with a non-zero continuation bit with no further digits should fail to decode.
      • A VLQ should decode with the correct order of digits (least to most significant).
      • A long VLQ with many trailing zero digits will decode.
    • A VLQ exceeding the 32-bit size limit is invalid (note: the spec is unclear on the details of this limit)
    • A VLQ at exactly the 32-bit size limit should be decoded (positive and negative).
• Basic format
  • version field
    • Must be present
    • Must be a number
    • Must be 3
  • file field
    • Optional, allow missing
    • Must be a string? (spec is not clear)
  • sourceRoot field
    • Optional, allow missing
    • Must be a string? (spec is not clear)
  • sources field
    • Must be present
    • Must be an array
    • Array elements must be null or a string
  • sourcesContent field
    • Must be present
    • Must be an array
    • Array elements must be null or a string
  • names field
    • Must be present (note: the spec implies this but implementations may not agree)
    • Must be an array
    • Array elements must be strings
  • mappings field
    • Must be present
    • Must be a string
    • Empty string is valid
  • ignoreList field
    • Optional, allow missing
    • Must be an array
    • Array elements must be numbers
    • Elements must not be out of bounds for the sources list
  • Extra unrecognized fields are allowed
• Index maps
  • ? Must be mutually exclusive with non-index map?
  • file field
    • Optional, allow missing
    • Must be a string? (spec is not clear)
  • sections field
    • Must be present
    • Must be an array
    • An empty sections array is valid
    • Array elements are valid section objects
      • offset field
        • Must be present
        • line field
          • Must be present
          • Must be a number
        • column field
          • Must be present
          • Must be a number
      • map field
        • Must be present
        • Must be an object
        • Must be a valid source map
    • Sections are in order (the spec is not 100% clear, but assumption is increasing numeric order, may need subtests)
    • Sections are non-overlapping (the definition of overlap is not clear, may need subtests)
• Mappings format
  • Each line is separated by ";"
  • A line may consist of zero segments (e.g., ";;")
  • Each line consists only of segments separated by ","
  • Must have greater than zero fields (note: many implementations don't check)
  • Must have 1, 4, or 5 fields
  • The source index must not be out of bounds of the sources array
  • The name index must not be out of bounds of the names array
  • Absolute VLQ values must be non-negative
    • The column must be non-negative
    • The source index must be non-negative
    • The original line must be non-negative
    • The original column must be non-negative
    • The name index must be non-negative
  • Relative VLQ values must be non-negative after adding to previous value
    • The column must be non-negative
    • The source index must be non-negative
    • The original line must be non-negative
    • The original column must be non-negative
    • The name index must be non-negative
• Ignore list
  • An ignore list is optional, may be missing
  • An ignore list can't be a non-array value
    • An ignore list can be empty
    • An ignore list entry must be a number
    • An ignore list entry cannot be out-of-bounds of the sources array
  • Ignore list entries are detected and are present
  • Items not specified in the ignore list don't show up as ignored
• Mappings semantics
  • A source map with no mappings does not map any position.
  • A single field segment gets mapped to the correct line and column.
  • A four field segment gets mapped to the correct line and column.
  • A five field segment gets mapped to the correct line and column.
  • When a name is present in a segment, it is correctly mapped.
  • When a source is present in a segment, it is correctly mapped.
  • The second occurence of a field segment in a line is mapped relative to the previous one.
  • When a new line starts, the generated column field resets to zero rather than being relative to the previous line.
  • For fields other than the generated column, a segment field that has occured once in a previous line is mapped relatively when it occurs in the next line.
  • Ensure that a transitive source map mapping works as expected
  • Index maps are correctly used in mappings
    • An index map with one sub-map will map correctly.
    • An index map with multiple sub-maps will map correctly, with appropriate offsets for the second and later sub-maps.
• Resolution of sources
  • When sourceRoot is provided, it is prepended to any sources entries and will be mapped with the full URL.
  • If the source URL is an absolute URL, it is resolved as an absolute URL.
  • If the source URL is a relative URL, it is resolved relative to the source map path.
• Wasm support
  • Create versions of the tests that use a Wasm source.

Scopes Proposal

TODO