implement rect() and add unit test.

fix for #100

src/context.js

@@ -770,16 +770,28 @@ class Context {
     }
 
     /**
-     * Rect
+     * @see https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/rect
+     * Draws a rectangle with the upper left corner at the specified (x, y)
      *
-     * @ignore
+     * @returns {void}
+     *
+     * @memberof Context
+     *
+     *
+     * @param {number}  x         The x coordinate of the rectangle
+     * @param {number}  y         The y coordinate of the rectangle
+     * @param {number}  width     The width of the rectangle
+     * @param {number}  height    The height of the rectangle
      *
-     * @throws {Error} Method is not yet implemented
      *
      * @memberof Context
      */
-    rect() {
-        throw new Error("rect not yet supported");
+    rect(x,y,width,height) {
+        this.moveTo(x,y);
+        this.lineTo(x+width,y);
+        this.lineTo(x+width,y+height);
+        this.lineTo(x,y+height);
+        this.lineTo(x,y);
     }
 
     /**
@@ -1143,7 +1155,7 @@ class Context {
                 let green = (greenNibble << 4) | greenNibble;
                 let blueNibble = parseInt(str[3], 16);
                 let blue = (blueNibble << 4) | blueNibble;
-                
+
                 let int = uint32.toUint32(red << 16 | green << 8 | blue);
                 int = uint32.shiftLeft(int,8);
                 return uint32.or(int,0xff);
@@ -1157,7 +1169,7 @@ class Context {
                 let blue = (blueNibble << 4) | blueNibble;
                 let alphaNibble = parseInt(str[4], 16);
                 let alpha = (alphaNibble << 4) | alphaNibble;
-                
+
                 let int = uint32.toUint32(red << 16 | green << 8 | blue);
                 int = uint32.shiftLeft(int,8);
                 return uint32.or(int,alpha);

tests/unit/specs/path.test.js

@@ -18,8 +18,7 @@ describe('draw curve',() => {
         done()
     })
 
-    //draw square
-    it('making a square', (done) => {
+    it('making a square with lines', (done) => {
         c.beginPath()
         c.moveTo(10,10)
         c.lineTo(100,10)
@@ -35,6 +34,18 @@ describe('draw curve',() => {
         done()
     })
 
+    it('making a square with rect', (done) => {
+        c.beginPath()
+        c.rect(10,10,90,90)
+        c.fillStyle = 'black'
+        c.fill()
+        expect(image.getPixelRGBA(0,0)).toBe(WHITE)
+        expect(image.getPixelRGBA(11,11)).toBe(BLACK)
+        expect(image.getPixelRGBA(50,50)).toBe(BLACK)
+        expect(image.getPixelRGBA(100,100)).toBe(WHITE)
+        done()
+    })
+
     //draw bezier curve
     it('bezier curve', (done) => {
         c.fillStyle = 'white'