fix: minItems for relevant geometry types

json/geometry.json

@@ -64,7 +64,7 @@
           "items": {
             "$ref": "#/definitions/position"
           },
-          "minLength": 2
+          "minItems": 2
         }
       },
       "additionalProperties": false
@@ -85,8 +85,9 @@
             "items": {
               "$ref": "#/definitions/position"
             },
-            "minLength": 2
-          }
+            "minItems": 2
+          },
+          "minItems": 1
         }
       },
       "additionalProperties": false
@@ -104,7 +105,8 @@
           "type": "array",
           "items": {
             "$ref": "#/definitions/linearRing"
-          }
+          },
+          "minItems": 1
         }
       },
       "additionalProperties": false
@@ -122,7 +124,8 @@
           "type": "array",
           "items": {
             "$ref": "#/definitions/position"
-          }
+          },
+          "minItems": 1
         }
       },
       "additionalProperties": false
@@ -142,8 +145,10 @@
             "type": "array",
             "items": {
               "$ref": "#/definitions/linearRing"
-            }
-          }
+            },
+            "minItems": 1
+          },
+          "minItems": 1
         }
       },
       "additionalProperties": false

src/index.ts

@@ -83,12 +83,18 @@ function encodePoint({ coordinates }: Point): GeometryProto {
 function decodeLineString({
   coordinates: rawCoords,
 }: GeometryProto): LineString {
+  const coordinates = readPositionArray(rawCoords, {
+    start: 0,
+    length: rawCoords.length / 2,
+  })
+  assertLengthIsAtLeast(
+    coordinates,
+    2,
+    'LineString must have at least 2 positions'
+  )
   return {
     type: 'LineString',
-    coordinates: readPositionArray(rawCoords, {
-      start: 0,
-      length: rawCoords.length / 2,
-    }),
+    coordinates,
   }
 }
 
@@ -104,21 +110,39 @@ function decodeMultiLineString({
   coordinates: rawCoords,
   lengths,
 }: GeometryProto): MultiLineString {
-  let coordinates: Position[][]
+  let coordinates
 
   if (lengths.length === 0) {
-    coordinates = [
-      readPositionArray(rawCoords, { start: 0, length: rawCoords.length / 2 }),
-    ]
+    const line = readPositionArray(rawCoords, {
+      start: 0,
+      length: rawCoords.length / 2,
+    })
+    assertLengthIsAtLeast(
+      line,
+      2,
+      'MultiLineString line must have at least 2 positions'
+    )
+    coordinates = [line]
   } else {
     let start = 0
     coordinates = lengths.map((length) => {
       const line = readPositionArray(rawCoords, { start, length })
+      assertLengthIsAtLeast(
+        line,
+        2,
+        'MultiLineString line must have at least 2 positions'
+      )
       start += length * 2
       return line
     })
   }
 
+  assertLengthIsAtLeast(
+    coordinates,
+    1,
+    'MultiLineString must have at least 1 line'
+  )
+
   return {
     type: 'MultiLineString',
     coordinates,
@@ -140,12 +164,14 @@ function encodeMultiLineString({
 function decodeMultiPoint({
   coordinates: rawCoords,
 }: GeometryProto): MultiPoint {
+  const coordinates = readPositionArray(rawCoords, {
+    start: 0,
+    length: rawCoords.length / 2,
+  })
+  assertLengthIsAtLeast(coordinates, 1, 'MultiPoint must have at least 1 point')
   return {
     type: 'MultiPoint',
-    coordinates: readPositionArray(rawCoords, {
-      start: 0,
-      length: rawCoords.length / 2,
-    }),
+    coordinates,
   }
 }
 
@@ -174,6 +200,7 @@ function decodePolygon({
     rings[i] = ring
     start += length * 2
   }
+  assertLengthIsAtLeast(rings, 1, 'Polygon must have at least 1 ring')
   return {
     type: 'Polygon',
     coordinates: rings,
@@ -195,7 +222,7 @@ function decodeMultiPolygon({
   lengths,
 }: GeometryProto): MultiPolygon {
   lengths = lengths.length === 0 ? [1, 1, rawCoords.length / 2] : lengths
-  const polygons = new Array<LinearRing[]>(lengths[0])
+  const polygons = new Array<BuildArrayMinLength<LinearRing, 1, []>>(lengths[0])
   let start = 0
   for (let i = 0, j = 1; i < lengths[0]; i++) {
     const ringsLength = lengths[j + i]
@@ -211,8 +238,14 @@ function decodeMultiPolygon({
       start += length * 2
     }
     j += ringsLength
+    assertLengthIsAtLeast(rings, 1, 'Polygon must have at least 1 ring')
     polygons[i] = rings
   }
+  assertLengthIsAtLeast(
+    polygons,
+    1,
+    'MultiPolygon must have at least 1 polygon'
+  )
   return {
     type: 'MultiPolygon',
     coordinates: polygons,
@@ -260,9 +293,7 @@ const validateLatitude = rangeValidator(90)
 const validateLongitude = rangeValidator(180)
 
 function validateLinearRing(ring: Position[]): asserts ring is LinearRing {
-  if (ring.length < 4) {
-    throw new Error('Invalid number of coordinates in linear ring')
-  }
+  assertLengthIsAtLeast(ring, 4, 'Invalid number of coordinates in linear ring')
 }
 
 function readPositionArray(
@@ -287,6 +318,22 @@ function readPositionArray(
   return positions
 }
 
+type BuildArrayMinLength<
+  T,
+  N extends number,
+  Current extends T[],
+> = Current['length'] extends N
+  ? [...Current, ...T[]]
+  : BuildArrayMinLength<T, N, [...Current, T]>
+
+function assertLengthIsAtLeast<T, N extends number>(
+  arr: T[],
+  length: N,
+  message: string
+): asserts arr is BuildArrayMinLength<T, N, []> {
+  if (arr.length < length) throw new Error(message)
+}
+
 class ExhaustivenessError extends Error {
   constructor(
     value: never,

test/fixture/bad-proto/linestring-no-coordinates.json

@@ -0,0 +1,5 @@
+{
+  "type": "TYPE_LINE_STRING",
+  "coordinates": [],
+  "lengths": []
+}

test/fixture/bad-proto/multilinestring-no-coordinates.json

@@ -0,0 +1,5 @@
+{
+  "type": "TYPE_MULTI_LINE_STRING",
+  "coordinates": [],
+  "lengths": []
+}

test/fixture/bad-proto/multipoint-no-coordinates.json

@@ -0,0 +1,5 @@
+{
+  "type": "TYPE_MULTI_POINT",
+  "coordinates": [],
+  "lengths": []
+}

test/fixture/bad-proto/multipolygon-no-coordinates.json

@@ -0,0 +1,5 @@
+{
+  "type": "TYPE_MULTI_POLYGON",
+  "coordinates": [],
+  "lengths": []
+}

test/fixture/bad-proto/polygon-no-coordinates.json

@@ -0,0 +1,5 @@
+{
+  "type": "TYPE_POLYGON",
+  "coordinates": [],
+  "lengths": []
+}

test/fixture/bad-proto/too-big-length-multilinestring.json

@@ -1,5 +1,5 @@
 {
-  "type": "MultiLineString",
+  "type": "TYPE_MULTI_LINE_STRING",
   "lengths": [2, 1],
   "coordinates": [12, 34]
 }

test/fixture/bad-proto/too-short-default-length-multilinestring.json

@@ -0,0 +1,5 @@
+{
+  "type": "TYPE_MULTI_LINE_STRING",
+  "lengths": [],
+  "coordinates": [1, 2]
+}

test/fixture/bad-proto/too-short-line-multilinestring.json

@@ -1,5 +1,5 @@
 {
-  "type": "MultiLineString",
+  "type": "TYPE_MULTI_LINE_STRING",
   "lengths": [2, 1],
   "coordinates": [170.0, 45.0, 180.0, 45.0, -180.0, 45.0]
 }

test/fixture/bad-proto/too-short-linestring.json

@@ -1,5 +1,5 @@
 {
-  "type": "LineString",
+  "type": "TYPE_LINE_STRING",
   "lengths": [],
   "coordinates": [-170, 10]
 }