Merge pull request #100 from ngittlen/master

Added tests for the A* algorithm and cleaned up A* directories

Author: TheSTL

src/_PathFinder_/AStar/AStar.test.js

@@ -0,0 +1,122 @@
+const { AStar } = require('.');
+
+describe('A*', () => {
+  describe('Completes grid successfully', () => {
+    it('A*', () => {
+      const inputGrid = [
+        [1, 1, 1, 0, 0, 0],
+        [1, 0, 1, 1, 1, 1],
+        [1, 0, 0, 0, 0, 0],
+        [1, 1, 1, 1, 1, 1],
+      ];
+      const ROW = inputGrid.length;
+      const COL = inputGrid[0].length;
+      const start = {
+        i: 0,
+        j: 0,
+      };
+      const end = {
+        i: 3,
+        j: 5,
+      };
+      const completedPath = [[3, 5], [3, 4], [3, 3], [3, 2], [3, 1], [2, 0], [1, 0], [0, 0]];
+      expect(AStar(start, end, ROW, COL, inputGrid)).toEqual(completedPath);
+    });
+  });
+
+  describe('Completes large grid successfully', () => {
+    it('A*', () => {
+      const inputGrid = [
+        [1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 1, 1],
+        [1, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1],
+        [1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1],
+        [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1],
+        [1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 1],
+        [0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1],
+        [0, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0],
+        [0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0],
+        [0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1],
+      ];
+      const ROW = inputGrid.length;
+      const COL = inputGrid[0].length;
+      const start = {
+        i: 0,
+        j: 0,
+      };
+      const end = {
+        i: 8,
+        j: 11,
+      };
+      const completedPath = [[8, 11], [8, 10], [7, 9], [6, 8], [5, 9], [5, 10],
+        [4, 11], [3, 11], [2, 11], [1, 11], [0, 10], [1, 9], [0, 8], [1, 7],
+        [1, 6], [2, 5], [2, 4], [2, 3], [2, 2], [2, 1], [1, 0], [0, 0]];
+      expect(AStar(start, end, ROW, COL, inputGrid)).toEqual(completedPath);
+    });
+  });
+
+  describe('Cannot complete grid successfully', () => {
+    it('A*', () => {
+      const inputGrid = [
+        [1, 1, 1, 0, 0, 0],
+        [0, 0, 0, 0, 0, 0],
+        [1, 0, 0, 0, 0, 0],
+        [1, 1, 1, 1, 1, 1],
+      ];
+      const ROW = inputGrid.length;
+      const COL = inputGrid[0].length;
+      const start = {
+        i: 0,
+        j: 0,
+      };
+      const end = {
+        i: 3,
+        j: 5,
+      };
+      expect(() => { AStar(start, end, ROW, COL, inputGrid); }).toThrowError('Error: Endpoint cannot be reached');
+    });
+  });
+
+  describe('Endpoint out of grid bounds', () => {
+    it('A*', () => {
+      const inputGrid = [
+        [1, 1, 1, 0, 0, 0],
+        [0, 0, 0, 0, 0, 0],
+        [1, 0, 0, 0, 0, 0],
+        [1, 1, 1, 1, 1, 1],
+      ];
+      const ROW = inputGrid.length;
+      const COL = inputGrid[0].length;
+      const start = {
+        i: 0,
+        j: 0,
+      };
+      const end = {
+        i: 5,
+        j: 5,
+      };
+      expect(() => { AStar(start, end, ROW, COL, inputGrid); }).toThrowError('Error: Endpoint outside grid bounds');
+    });
+  });
+
+  describe('Endpoint value is zero', () => {
+    it('A*', () => {
+      const inputGrid = [
+        [1, 1, 1, 0, 0, 0],
+        [0, 0, 0, 0, 0, 0],
+        [1, 0, 0, 0, 0, 0],
+        [1, 1, 1, 1, 1, 1],
+      ];
+      const ROW = inputGrid.length;
+      const COL = inputGrid[0].length;
+      const start = {
+        i: 0,
+        j: 0,
+      };
+      const end = {
+        i: 1,
+        j: 3,
+      };
+      expect(() => { AStar(start, end, ROW, COL, inputGrid); }).toThrowError('Error: Endpoint is unreachable');
+    });
+  });
+});

src/PathFinder/AStart/index.js src/_PathFinder_/AStar/index.js

@@ -9,6 +9,15 @@ function AStar(s, e, row, col, inputGrid) {
   const Col = col;
   const start = s;
   const end = e;
+  const path = [];
+
+  if (end.i >= inputGrid.length || end.j >= inputGrid[0].length) {
+    throw new Error('Error: Endpoint outside grid bounds');
+  }
+
+  if (inputGrid[end.i][end.j] === 0) {
+    throw new Error('Error: Endpoint is unreachable');
+  }
 
   function cell() {
     this.cellValue = null;
@@ -53,7 +62,6 @@ function AStar(s, e, row, col, inputGrid) {
 
     let i = endRow;
     let j = endCol;
-    const path = [];
 
     while (!(i === startRow && j === startCol)) {
       path.push([i, j]);
@@ -64,10 +72,6 @@ function AStar(s, e, row, col, inputGrid) {
       j = nextJ;
     }
     path.push([i, j]);
-
-    for (let i = 0; i < path.length; i += 1) {
-      console.log(path[i]);
-    }
   };
 
   const neighbourExplorer = (i, j, parentI, parentJ, openList, openListMap,
@@ -173,7 +177,10 @@ function AStar(s, e, row, col, inputGrid) {
     }
     return true;
   };
-  search();
+  if (!search()) {
+    throw new Error('Error: Endpoint cannot be reached');
+  }
+  return path;
 }