Increase coverage Tangent Between Circles (manrajgrover#36)

test/algorithms/geometry/testTangentBetweenCircles.js

@@ -0,0 +1,27 @@
+/* eslint-env mocha */
+const CircleTangents = require('../../../src').algorithms.geometry.CircleTangents;
+
+const assert = require('assert');
+
+describe('Tangent Between Circles', () => {
+  it('should return empty arrays if tangents do not exist (one circle is contained in the other)', () => {
+    const circles = new CircleTangents(0, 0, 1, 0, 0, 0.5);
+    assert.deepEqual(circles.tangents, [[], [], [], []]);
+  });
+
+  it('should return 2 external tangents (circles overlap)', () => {
+    const tangents = new CircleTangents(0, 0, 1, 1, 0, 1).tangents;
+    assert.deepEqual(tangents[0], [0, 1, 1, 1]);
+    assert.deepEqual(tangents[1], [0, -1, 1, -1]);
+    assert.deepEqual(tangents[2], []);
+    assert.deepEqual(tangents[3], []);
+  });
+
+  it('should return 2 external and 2 internal tangents (circles do not overlap)', () => {
+    const tangents = new CircleTangents(0, 0, 1, 2, 0, 1).tangents;
+    assert.deepEqual(tangents[0], [0, 1, 2, 1]);
+    assert.deepEqual(tangents[1], [0, -1, 2, -1]);
+    assert.deepEqual(tangents[2], [1, 0, 1, 0]);
+    assert.deepEqual(tangents[3], [1, 0, 1, 0]);
+  });
+});