diff --git a/test/equals.test.js b/test/equals.test.js
index dd3c64056..433462a33 100644
--- a/test/equals.test.js
+++ b/test/equals.test.js
@@ -21,3 +21,16 @@ test('[1,2,3] is not equal to [1,2,4]', () => {
 test('[1, 2, 3] should be equal to { 0: 1, 1: 2, 2: 3 }) - type is different, but their enumerable properties match.', () => {
   expect(equals([1, 2, 3], { 0: 1, 1: 2, 2: 3 })).toBeTruthy();
 });
+const date = new Date();
+test('Two of the same date are equal', () => {
+  expect(equals(date, date)).toBeTruthy();
+});
+test('null should not be equal to anything', () => {
+  expect(equals(null, 'test')).toBeFalsy();
+});
+test('undefined should not be equal to anything', () => {
+  expect(equals(undefined, 'test')).toBeFalsy();
+});
+test('{a: ""} should not be equal to {a: "", b: ""}', () => {
+  expect(equals({a: ''}, {a: '', b: ''})).toBeFalsy();
+});
diff --git a/test/sumBy.test.js b/test/sumBy.test.js
index 3fcd55f68..90523040b 100644
--- a/test/sumBy.test.js
+++ b/test/sumBy.test.js
@@ -4,3 +4,9 @@ const {sumBy} = require('./_30s.js');
 test('sumBy is a Function', () => {
   expect(sumBy).toBeInstanceOf(Function);
 });
+test('Works with a callback.', () => {
+  expect(sumBy([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], o => o.n)).toBe(20);
+});
+test('Works with a property name.', () => {
+  expect(sumBy([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], 'n')).toBe(20);
+});
\ No newline at end of file
diff --git a/test/take.test.js b/test/take.test.js
index 7506eea2d..b25bbf1c0 100644
--- a/test/take.test.js
+++ b/test/take.test.js
@@ -10,3 +10,6 @@ test('Returns an array with n elements removed from the beginning.', () => {
 test('Returns an array with n elements removed from the beginning.', () => {
   expect(take([1, 2, 3], 0)).toEqual([]);
 });
+test('Returns an array with n elements removed from the beginning.', () => {
+  expect(take([1, 2, 3])).toEqual([1]);
+});
diff --git a/test/takeWhile.test.js b/test/takeWhile.test.js
index b726f5e6e..29cb6187b 100644
--- a/test/takeWhile.test.js
+++ b/test/takeWhile.test.js
@@ -7,3 +7,6 @@ test('takeWhile is a Function', () => {
 test('Removes elements until the function returns true', () => {
   expect(takeWhile([1, 2, 3, 4], n => n >= 3)).toEqual([1, 2]);
 });
+test('Removes elements until the function returns true', () => {
+  expect(takeWhile([1, 2, 3, 4], n => false)).toEqual([1, 2, 3, 4]);
+});
diff --git a/test/timeTaken.test.js b/test/timeTaken.test.js
index 72436f8b6..fc3cb21a6 100644
--- a/test/timeTaken.test.js
+++ b/test/timeTaken.test.js
@@ -4,3 +4,6 @@ const {timeTaken} = require('./_30s.js');
 test('timeTaken is a Function', () => {
   expect(timeTaken).toBeInstanceOf(Function);
 });
+test('timeTaken is a Function', () => {
+  expect(timeTaken(() => 10)).toBe(10);
+});