Designation

JEST test methods

Matchers

it("Matchers", () => {
expect(24 + 20).toBe(44);
expect({ one: 1, two: 3 }).toEqual({ one: 1, two: 3 });
for (let i = 1; i < 10; i++) {
for (let j = 1; j < 10; j++) {
expect(i + j).not.toBe(0);
}
}
});

Truetiness

it("Truetiness", () => {
const isActive = null;
expect(isActive).toBeNull();
expect(isActive).toBeDefined();
expect(isActive).not.toBeUndefined();
expect(isActive).not.toBeTruthy();
expect(isActive).toBeFalsy();
 });

Zeros

it("zeros", () => {
const z = 0;
expect(z).not.toBeNull();
expect(z).toBeDefined();
expect(z).not.toBeUndefined();
expect(z).not.toBeTruthy();
expect(z).toBeFalsy();
});

Numbers

it("Numbers", () => {
const value = 100 + 200;
expect(value).toBeGreaterThan(200);
expect(value).toBeGreaterThanOrEqual(200);
expect(value).toBeLessThan(500);
expect(value).toBeLessThanOrEqual(300);
expect(value).toBe(300);
expect(value).toEqual(300);
 });

Strings

expect('team').not.toMatch(/I/);
expect('Christoph').toMatch(/stop/);

Arrays

it("Arrays", () => {
const resources = [
 "Patients",
 "Practitioners",
 "Accountants",
 "Employer",
 "Appointments"
 ];
 expect(resources).toContain("Accountants");
 });

Exceptions

it("Exceptions", () => {
const t = () => {
throw new TypeError();
};
 expect(t).toThrow(TypeError);
 });