Letting LngLatBounds.extend accepts LngLatLike and LngLatBoundsLike…

… as well. (mapbox#9293)

* Changing the input type of the extend function to LngLatLike and LngLatBoundsLike and fixing a bug identified in the function

* Updating the function's comment to show the correct parameter type.

* -Adding more test cases:
	- Extend with an array of 3 elements
	- Extend with an empty array
-Removing unnecessary comments.

* Adding a better documentation to be more clear on what  can be inputted in extend function.

* -Resolving the flow failures which was causing CI pipeline failure.
-Correcting the comments for the extend function.

src/geo/lng_lat_bounds.js

@@ -61,12 +61,12 @@ class LngLatBounds {
     }
 
     /**
-     * Extend the bounds to include a given LngLat or LngLatBounds.
+     * Extend the bounds to include a given LngLatLike or LngLatBoundsLike.
      *
-     * @param {LngLat|LngLatBounds} obj object to extend to
+     * @param {LngLatLike|LngLatBoundsLike} obj object to extend to
      * @returns {LngLatBounds} `this`
      */
-    extend(obj: LngLat | LngLatBounds) {
+    extend(obj: LngLatLike | LngLatBoundsLike) {
         const sw = this._sw,
             ne = this._ne;
         let sw2, ne2;
@@ -83,10 +83,12 @@ class LngLatBounds {
 
         } else {
             if (Array.isArray(obj)) {
-                if (obj.every(Array.isArray)) {
-                    return this.extend(LngLatBounds.convert(obj));
+                if (obj.length === 4 || obj.every(Array.isArray)) {
+                    const lngLatBoundsObj = ((obj: any): LngLatBoundsLike);
+                    return this.extend(LngLatBounds.convert(lngLatBoundsObj));
                 } else {
-                    return this.extend(LngLat.convert(obj));
+                    const lngLatObj = ((obj: any): LngLatLike);
+                    return this.extend(LngLat.convert(lngLatObj));
                 }
             }
             return this;

test/unit/geo/lng_lat_bounds.test.js

@@ -60,12 +60,20 @@ test('LngLatBounds', (t) => {
         t.equal(bounds.getNorth(), 10);
         t.equal(bounds.getEast(), 10);
 
+        bounds.extend([-20, -20, 100]);
+
+        t.equal(bounds.getSouth(), -20);
+        t.equal(bounds.getWest(), -20);
+        t.equal(bounds.getNorth(), 10);
+        t.equal(bounds.getEast(), 10);
+
         t.end();
     });
 
     t.test('#extend with bounds', (t) => {
         const bounds1 = new LngLatBounds([0, 0], [10, 10]);
         const bounds2 = new LngLatBounds([-10, -10], [10, 10]);
+
         bounds1.extend(bounds2);
 
         t.equal(bounds1.getSouth(), -10);
@@ -81,6 +89,14 @@ test('LngLatBounds', (t) => {
         t.equal(bounds1.getNorth(), 15);
         t.equal(bounds1.getEast(), 15);
 
+        const bounds4 = new LngLatBounds([-20, -20, 20, 20]);
+        bounds1.extend(bounds4);
+
+        t.equal(bounds1.getSouth(), -20);
+        t.equal(bounds1.getWest(), -20);
+        t.equal(bounds1.getNorth(), 20);
+        t.equal(bounds1.getEast(), 20);
+
         t.end();
     });
 
@@ -125,6 +141,17 @@ test('LngLatBounds', (t) => {
         t.end();
     });
 
+    t.test('#extend with empty array', (t) => {
+        const point = new LngLat(0, 0);
+        const bounds = new LngLatBounds(point, point);
+
+        t.throws(() => {
+            bounds.extend([]);
+        }, "`LngLatLike` argument must be specified as a LngLat instance, an object {lng: <lng>, lat: <lat>}, an object {lon: <lng>, lat: <lat>}, or an array of [<lng>, <lat>]", 'detects and throws on invalid input');
+
+        t.end();
+    });
+
     t.test('accessors', (t) => {
         const sw = new LngLat(0, 0);
         const ne = new LngLat(-10, -20);