diff --git a/.codeclimate.yml b/.codeclimate.yml
index 9a7575a..fa4a7f7 100644
--- a/.codeclimate.yml
+++ b/.codeclimate.yml
@@ -2,4 +2,5 @@ version: '2'
 
 exclude_patterns:
   - '**/test/'
+  - '**/examples/'
   - '.yarn/'
diff --git a/src/Deque.ts b/src/Deque.ts
index 8096c70..7c0cb4c 100644
--- a/src/Deque.ts
+++ b/src/Deque.ts
@@ -1,6 +1,10 @@
 // Deque is based on https://github.com/petkaantonov/deque/blob/master/js/deque.js
 // Released under the MIT License: https://github.com/petkaantonov/deque/blob/6ef4b6400ad3ba82853fdcc6531a38eb4f78c18c/LICENSE
 /*eslint-disable*/
+export const MIN_CAPACITY = 4;
+export const MAX_CAPACITY = 1073741824;
+export const RESIZE_MULTIPLER = 1;
+
 function arrayMove(src: any[], srcIndex: number, dst: any[], dstIndex: number, len: number) {
   for (let j = 0; j < len; ++j) {
     dst[j + dstIndex] = src[j + srcIndex];
@@ -20,10 +24,6 @@ function pow2AtLeast(n: number) {
   return n + 1;
 }
 
-export const MIN_CAPACITY = 4;
-export const MAX_CAPACITY = 1073741824;
-export const RESIZE_MULTIPLER = 1;
-
 export function getCapacity(capacity: number) {
   return pow2AtLeast(Math.min(Math.max(MIN_CAPACITY, capacity), MAX_CAPACITY));
 }
diff --git a/src/Sema.ts b/src/Sema.ts
index a1681a6..35a7a9d 100644
--- a/src/Sema.ts
+++ b/src/Sema.ts
@@ -41,7 +41,7 @@ export class Sema<T = string> {
       capacity?: number;
     } = {},
   ) {
-    if (isFn(pauseFn) !== isFn(resumeFn)) {
+    if (isFn(pauseFn) && !isFn(resumeFn)) {
       throw new Error('pauseFn and resumeFn must be both set for pausing');
     }
 
diff --git a/test/Sema.ts b/test/Sema.ts
index df4ca97..190d536 100644
--- a/test/Sema.ts
+++ b/test/Sema.ts
@@ -1,25 +1,8 @@
-import { Sema } from '../src/index';
+import { Sema } from '../src/Sema';
 
-describe('General', () => {
-  test('Pausing works', () => {
-    const pauseFn = jest.fn();
-    const resumeFn = jest.fn();
-    const s = new Sema(5, { pauseFn, resumeFn });
-
-    for (let i = 0; i < 5; i += 1) {
-      // eslint-disable-next-line
-      s.acquire().catch(console.error);
-    }
-
-    expect(pauseFn).not.toHaveBeenCalled();
-    expect(resumeFn).not.toHaveBeenCalled();
-
-    // eslint-disable-next-line
-    s.acquire().catch(console.error);
-    expect(pauseFn).toHaveBeenCalled();
-    s.release();
-    s.release();
-    expect(resumeFn).toHaveBeenCalled();
+describe('Sema.constructor', () => {
+  it('should throw an error if a pauseFn is passed, but a resumeFn isnt', () => {
+    expect(() => new Sema(3, { pauseFn: () => 3 })).toThrow();
   });
 
   test('initFn is called properly', () => {
@@ -29,6 +12,17 @@ describe('General', () => {
     expect(s).toBeInstanceOf(Sema);
     expect(initFn).toHaveReturnedTimes(3);
   });
+});
+
+describe('Sema.acquire', () => {
+  it('should aquire a sephamore', async () => {
+    const s = new Sema(1);
+
+    const token = await s.acquire();
+
+    expect(token).toBe('1');
+    expect(s.waiting()).toEqual(0);
+  });
 
   test('Tokens are returned properly', async () => {
     let maxConcurrency = 0;
@@ -47,17 +41,6 @@ describe('General', () => {
   });
 });
 
-describe('Sema.acquire', () => {
-  it('should aquire a sephamore', async () => {
-    const s = new Sema(1);
-
-    const token = await s.acquire();
-
-    expect(token).toBe('1');
-    expect(s.waiting()).toEqual(0);
-  });
-});
-
 describe('Sema.tryAcquire', () => {
   it('should return undefined no sephamores are free', async () => {
     const s = new Sema(1);
@@ -79,6 +62,59 @@ describe('Sema.release', () => {
     expect(s.tryAcquire()).toBeDefined();
     expect(s.tryAcquire()).toBeUndefined();
   });
+
+  it('should use the release token value if an initFn is passed during instance creation', () => {
+    const s = new Sema(1, { initFn: () => 1 });
+
+    /* eslint-disable @typescript-eslint/ban-ts-comment, no-underscore-dangle */
+
+    // @ts-expect-error
+    const spy = jest.spyOn(s.releaseEmitter, 'emit');
+
+    /* eslint-enable */
+
+    expect(s.tryAcquire()).toBeDefined();
+
+    s.release(1);
+
+    expect(spy).toHaveBeenCalledWith('release', 1);
+  });
+
+  it('should use the default token value if an initFn is not passed during instance creation', () => {
+    const s = new Sema(1);
+
+    /* eslint-disable @typescript-eslint/ban-ts-comment, no-underscore-dangle */
+    // @ts-expect-error
+    const spy = jest.spyOn(s.releaseEmitter, 'emit');
+    /* eslint-enable */
+
+    expect(s.tryAcquire()).toBeDefined();
+
+    s.release();
+
+    expect(spy).toHaveBeenCalledWith('release', '1');
+  });
+
+  it('should execute the pause function once the limit is met', () => {
+    const pauseFn = jest.fn();
+    const resumeFn = jest.fn();
+    const s = new Sema(5, { pauseFn, resumeFn });
+
+    for (let i = 0; i < 5; i += 1) {
+      // eslint-disable-next-line
+      s.acquire().catch(console.error);
+    }
+
+    expect(pauseFn).not.toHaveBeenCalled();
+    expect(resumeFn).not.toHaveBeenCalled();
+
+    // eslint-disable-next-line
+    s.acquire().catch(console.error);
+    expect(pauseFn).toHaveBeenCalled();
+    s.release();
+    s.release();
+    expect(resumeFn).toHaveBeenCalled();
+  });
 });
 
 describe('Sema.waiting', () => {
@@ -131,7 +167,7 @@ describe('Sema.waiting', () => {
     expect(s.waiting()).toEqual(0);
   });
 
-  it('should hanlde greater maxConcurrency', async () => {
+  it('should handle greater maxConcurrency', async () => {
     const s = new Sema(3);
 
     await s.acquire();
@@ -144,3 +180,16 @@ describe('Sema.waiting', () => {
     expect(s.waiting()).toEqual(0);
   });
 });
+
+describe('Sema.drain', () => {
+  it('should acquire the maxConcurrency of sephamores', async () => {
+    const s = new Sema(3);
+
+    const spy = jest.spyOn(s, 'acquire');
+
+    const all = await s.drain();
+
+    expect(all.length).toBe(3);
+    expect(spy).toHaveBeenCalledTimes(3);
+  });
+});
diff --git a/test/Utils.ts b/test/Utils.ts
index cdf771d..7209165 100644
--- a/test/Utils.ts
+++ b/test/Utils.ts
@@ -1,5 +1,4 @@
 import { Sema } from '../src/Sema';
-
 import { createRateLimiter } from '../src/Utils';
 
 jest.useFakeTimers();
@@ -79,4 +78,12 @@ describe('createRateLimiter', () => {
 
     expect(acquireFn).toHaveBeenCalledTimes(1);
   });
+
+  it('should throw an error if the rptu is not an integer', () => {
+    expect(() => createRateLimiter(0.5)).toThrow();
+  });
+
+  it('should throw an error if the rptu is negative', () => {
+    expect(() => createRateLimiter(-5)).toThrow();
+  });
 });
diff --git a/test/index.ts b/test/index.ts
new file mode 100644
index 0000000..6e54e02
--- /dev/null
+++ b/test/index.ts
@@ -0,0 +1,13 @@
+import { Sema, createRateLimiter } from '../src/index';
+
+describe('Exports', () => {
+  it('should export Sema', () => {
+    expect(Sema).toBeDefined();
+    expect(Sema).toBeInstanceOf(Object);
+  });
+
+  it('should export createRateLimiter helper function', () => {
+    expect(createRateLimiter).toBeDefined();
+    expect(createRateLimiter).toBeInstanceOf(Function);
+  });
+});