Freeze Point objects to make them immutable

Author: lutovich

src/v1/spatial-types.js

@@ -23,6 +23,7 @@ const POINT_IDENTIFIER_PROPERTY = '__isPoint__';
 
 /**
  * Represents a single two or three-dimensional point in a particular coordinate reference system.
+ * Created <code>Point</code> objects are frozen with {@link Object#freeze()} in constructor and thus immutable.
  */
 export class Point {
 
@@ -31,13 +32,14 @@ export class Point {
    * @param {number|Integer} srid the coordinate reference system identifier.
    * @param {number} x the <code>x</code> coordinate of the point.
    * @param {number} y the <code>y</code> coordinate of the point.
-   * @param {number|undefined} z the <code>y</code> coordinate of the point or <code>undefined</code> if point has 2 dimensions.
+   * @param {number} [z=undefined] the <code>y</code> coordinate of the point or <code>undefined</code> if point has 2 dimensions.
    */
   constructor(srid, x, y, z) {
     this.srid = int(srid);
     this.x = x;
     this.y = y;
     this.z = z;
+    Object.freeze(this);
   }
 }
 

test/v1/spatial-types.test.js

@@ -65,6 +65,34 @@ describe('spatial-types', () => {
     }
   });
 
+  it('should expose frozen immutable points', () => {
+    const point = new Point(CARTESIAN_2D_CRS_CODE, 1.2, 3.4);
+
+    expect(Object.isFrozen(point)).toBeTruthy();
+
+    expect(point.srid).toEqual(CARTESIAN_2D_CRS_CODE);
+    expect(point.x).toEqual(1.2);
+    expect(point.y).toEqual(3.4);
+    expect(point.z).toBeUndefined();
+
+    try {
+      point.x = 5.6;
+    } catch (e) {
+    }
+    try {
+      point.y = 7.8;
+    } catch (e) {
+    }
+    try {
+      point.z = 9.0;
+    } catch (e) {
+    }
+
+    expect(point.x).toEqual(1.2);
+    expect(point.y).toEqual(3.4);
+    expect(point.z).toBeUndefined();
+  });
+
   it('should receive 2D points', done => {
     testReceivingOfPoints(done, 'RETURN point({x: 169.99, y: 12.1718})', point => {
       expect(isPoint(point)).toBeTruthy();