isValid2DCoordinate

[M-Scott-Lassiter]

Description

For testing 3D coordinates, see isValid3DCoordinate. For testing either, see isValidCoordinate.

This is one of the first building block matchers needed. Coordinates are the basis of all objects, and we need a way to reliably test that they have been formatted appropriately.

A GeoJSON Geometry object of any type other than "GeometryCollection" has a member with the name "coordinates". The value of the "coordinates" member is an array. The structure of the elements in this array is determined by the type of geometry. GeoJSON processors MAY interpret Geometry objects with empty "coordinates" arrays as null objects.
~ https://datatracker.ietf.org/doc/html/rfc7946#section-3.1

This matcher should limit its scope by only taking an argument of an individual array value (i.e. not the entire property).

A position is an array of numbers. There MUST be two or more elements. The first two elements are longitude and latitude, or easting and northing, precisely in that order and using decimal numbers. Altitude or elevation MAY be included as an optional third element.

Implementations SHOULD NOT extend positions beyond three elements because the semantics of extra elements are unspecified and ambiguous. Historically, some implementations have used a fourth element to carry a linear referencing measure (sometimes denoted as "M") or a numerical timestamp, but in most situations a parser will not be able to properly interpret these values. The interpretation and meaning of additional elements is beyond the scope of this specification, and additional elements MAY be ignored by parsers.
~ https://datatracker.ietf.org/doc/html/rfc7946#section-3.1.1

This matcher will enforce two-member arrays. Separate matchers will be used for 3D arrays and for validating that geometries and features have a correct coordinates key.

WGS84 Bounds: -180.0000, -90.0000, 180.0000, 90.0000
Projected Bounds: -180.0000, -90.0000, 180.0000, 90.0000
~ https://spatialreference.org/ref/epsg/wgs-84/
Also, see https://datatracker.ietf.org/doc/html/rfc7946#section-4

Any values outside of these WGS-84 standards should fail.

Valid GeoJSON Coordinate Examples

A two-element array of points:

{
   "type": "Feature",
   "geometry": {
       "type": "Point",
       "coordinates": [102.0, 0.5]
   },
   "properties": {
       "prop0": "value0"
   }
}

An array of coordinates:

{
   "type": "Feature",
   "geometry": {
       "type": "LineString",
       "coordinates": [
           [102.0, 0.0],
           [103.0, 1.0],
           [104.0, 0.0],
           [105.0, 1.0]
       ]
   }
}

{
   "type": "Polygon", // Or LineString
   "coordinates": [
       [
           [100.0, 0.0],
           [101.0, 0.0],
           [101.0, 1.0],
           [100.0, 1.0],
           [100.0, 0.0]
       ]
   ]
}

An array of arrays of coordinates:

{
   "type": "MultiLineString",
   "coordinates": [
       [
           [170.0, 45.0], [180.0, 45.0]
       ], [
           [-180.0, 45.0], [-170.0, 45.0]
       ]
   ]
}

{
   "type": "MultiPolygon",
   "coordinates": [
       [
           [
               [180.0, 40.0], [180.0, 50.0], [170.0, 50.0],
               [170.0, 40.0], [180.0, 40.0]
           ]
       ],
       [
           [
               [-170.0, 40.0], [-170.0, 50.0], [-180.0, 50.0],
               [-180.0, 40.0], [-170.0, 40.0]
           ]
       ]
   ]
}

In each case, the matcher should only get passed the value of a single coordinate, not the object itself.

Example Matcher Usage

expect([22, -34.549]).isValid2DCoordinate()
expect([22, -34.549, 22]).not.isValid2DCoordinate()
expect({coordinates: [22, -34.549, 22]}).not.isValid2DCoordinate()

Passing Tests

Values in Range

• Each hemisphere
  • [0, 0], [102.0, 0.5], [172.0, -15], [-10.9, 77], [-152.0, -33.33333]
• At the boundaries
  • [180, 0], [-180, 0], [0, 90], [0,-90], [180, 90], [180,-90], [-180, 90], [-180,-90]

Failing Tests

Coordinates input not an array

• undefined
• null
• Booleans: true, false
• Numbers: 200, -200, Infinity, -Infinity, NaN
• Objects: { coordinates: [0, 0] }
• Strings: '', 'Random Coordinate', '[0, 0]', '[[0, 0], [0, 0]]'

Incorrect number of array elements

• [ ], [ 20 ], [20, 30, 0], [20, 30, 0, 20, 30, 0, 20, 30, 0]

Coordinates out of range

• Latitude: [0, 90.0000001], [0, -90.0000001], [0, 900000], [0, -900000]
• Longitude: [180.0000001, 0], [-180.0000001, 0], [1800000, 0], [-1800000, 0]
• Both: [181, 91], [181, -91], [-181, 91], [-181, -91]

Coordinates have non-number values

• Each of the non-numeric values in "Coordinates input not an array" paired with a valid coordinate:
  • [<value>, 0]
  • [0, <value>]
  • [<value>, <value>]

Array nested too deeply

• [ [ [1, 1], [0, 0] ] ]
• [ [ [10, 20], [2, 59] ] ]
• [ [ [10, 20], [2, 90], [95, 5] ] ]
• [ [ [ [1, 1], [0, 0] ] ] ], [ [ [ [ [2, 2], [3, 3] ] ] ] ]

[M-Scott-Lassiter]

🎉 This issue has been resolved in version 1.0.0-beta.1 🎉

The release is available on:

• npm package (@beta dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[M-Scott-Lassiter]

🎉 This issue has been resolved in version 1.0.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀