add isComposit

Author: tdnelson2

index.js

@@ -17,6 +17,7 @@ module.exports = Object.assign(
   require('./lib/isAscending.js'),
   require('./lib/isDescending.js'),
   require('./lib/isPrime.js'),
+  require('./lib/isComposit.js'),
   require('./lib/maximum.js'),
   require('./lib/median.js'),
   require('./lib/minimum.js'),

lib/isComposit.js

@@ -0,0 +1,18 @@
+const { isPrime } = require('./isPrime');
+
+
+// `isPrime` checks if the number is an integer greater than 1
+// but since we simply want `isPrime` to check if this number
+// is prime, we need to do the check again to avoid a false result.
+const testComposit = num => (num % 1 || num < 2 ? false : !isPrime(num));
+
+/**
+ * This function evaluates whether all numerical parameters are composit
+ * @memberof variadic
+ * @author tdnelson2
+ * @param {...*} params - One or more parameters.
+ */
+exports.isComposit = (...params) => {
+  if (params.length === 0) throw new Error('Must provide one or more paramters');
+  return params.every(testComposit);
+};

spec/isCompositSpec.js

@@ -0,0 +1,40 @@
+const { isComposit } = require('../lib/isComposit');
+
+describe('IsComposit', () => {
+  it('should return true when all parameters evaluate to composit numbers', () => {
+    const result = isComposit(4, 6, 20 / 2, +'8');
+    expect(result).toBe(true);
+  });
+
+  it('should return false when at least one parameter does not evaluate to a composit number', () => {
+    const result = isComposit(2, 8, 10, 28);
+    expect(result).toBe(false);
+  });
+
+  it('should return false when at least one parameter does not evaluate to an integer', () => {
+    const result = isComposit(2.5, 8, 10, 20);
+    expect(result).toBe(false);
+  });
+
+  it('should return false when at least one parameter evaluates to a number less than 2', () => {
+    const result = isComposit(-2, 8, 10, 20);
+    expect(result).toBe(false);
+  });
+
+  it('should return false when the least factor of a number is not composit', () => {
+    const result = isComposit(15485863);
+    expect(result).toBe(false);
+  });
+
+  it('should throw an error when no parameters are provided', () => {
+    expect(isComposit).toThrow();
+  });
+
+  it('should throw an error when at least one parameter does not evaluate to a number', () => {
+    expect(() => isComposit('yo')).toThrow();
+  });
+
+  it('should throw an error when at least one parameter evaluates to a number larger than Number.MAX_SAFE_INTEGER', () => {
+    expect(() => isComposit(9949370777987917)).toThrow();
+  });
+});