Completed the Helper definitions.

turf/turf-test.ts

@@ -313,6 +313,36 @@ var snapped = turf.pointOnLine(line, point1);
 // Tests Helper
 //////////////////////////////////////////////////////////////////////////
 
+// -- Test featurecollection --
+var fc = turf.featurecollection([point1, point2]);
+
+// -- Test linestring --
+var linestring1 = turf.linestring([
+	[-21.964416, 64.148203],
+	[-21.956176, 64.141316],
+	[-21.93901, 64.135924],
+	[-21.927337, 64.136673]
+]);
+var linestring2 = turf.linestring([
+	[-21.929054, 64.127985],
+	[-21.912918, 64.134726],
+	[-21.916007, 64.141016],
+	[-21.930084, 64.14446]
+], {name: 'line 1', distance: 145});
+
+// -- Test point --
+var pt1 = turf.point([-75.343, 39.984]);
+var pt2 = turf.point([-75.343, 39.984], {name: 'point 1', distance: 145});
+
+// -- Test polygon --
+var polygon = turf.polygon([[
+ [-2.275543, 53.464547],
+ [-2.275543, 53.489271],
+ [-2.215118, 53.489271],
+ [-2.215118, 53.464547],
+ [-2.275543, 53.464547]
+]], { name: 'poly1', population: 400});
+
 //////////////////////////////////////////////////////////////////////////
 // Tests Data
 //////////////////////////////////////////////////////////////////////////

turf/turf.d.ts

@@ -261,6 +261,37 @@ declare module turf {
     // Helper
     //////////////////////////////////////////////////////
 
+    /**
+    * Takes one or more Features and creates a FeatureCollection.
+    * @param features Input features
+    * @returns A FeatureCollection of input features
+    */
+    function featurecollection(features: Array<GeoJSON.Feature>): GeoJSON.FeatureCollection;
+
+    /**
+    * Creates a LineString based on a coordinate array. Properties can be added optionally.
+    * @param coordinates An array of Positions
+    * @param [properties] An Object of key-value pairs to add as properties
+    * @returns A LineString feature
+    */
+    function linestring(coordinates: Array<Array<number>>, properties?: any): GeoJSON.Feature;
+
+    /**
+    * Takes coordinates and properties (optional) and returns a new Point feature.
+    * @param coordinates Longitude, latitude position (each in decimal degrees)
+    * @param [properties] An Object of key-value pairs to add as properties
+    * @returns A Point feature
+    */
+    function point(coordinates: Array<number>, properties?: any): GeoJSON.Feature;
+
+    /**
+    * Takes an array of LinearRings and optionally an Object with properties and returns a Polygon feature.
+    * @param rings An array of LinearRings
+    * @param [properties] An Object of key-value pairs to add as properties
+    * @returns A Polygon feature
+    */
+    function polygon(rings: Array<Array<Array<number>>>, properties?: any): GeoJSON.Feature;
+
     //////////////////////////////////////////////////////
     // Data
     //////////////////////////////////////////////////////