Solution

src/fillTank.test.js

@@ -1,9 +1,124 @@
 'use strict';
 
 describe('fillTank', () => {
-  // const { fillTank } = require('./fillTank');
+  const { fillTank } = require('./fillTank');
 
-  it('should ', () => {});
+  it('should fill the requested amount of fuel', () => {
+    const customer = {
+      money: 3000,
+      vehicle: {
+        maxTankCapacity: 40,
+        fuelRemains: 8,
+      },
+    };
 
-  // write tests here
+    fillTank(customer, 50, 10);
+
+    expect(customer.vehicle.fuelRemains).toBe(18);
+    expect(customer.money).toBe(2500);
+  });
+
+  it('should fill the tank fully if amount is not given', () => {
+    const customer = {
+      money: 3000,
+      vehicle: {
+        maxTankCapacity: 40,
+        fuelRemains: 8,
+      },
+    };
+
+    fillTank(customer, 50);
+
+    expect(customer.vehicle.fuelRemains).toBe(40);
+    expect(customer.money).toBe(1400);
+  });
+
+  it('should fill only free space if requested amount is too big', () => {
+    const customer = {
+      money: 3000,
+      vehicle: {
+        maxTankCapacity: 40,
+        fuelRemains: 35,
+      },
+    };
+
+    fillTank(customer, 50, 10);
+
+    expect(customer.vehicle.fuelRemains).toBe(40);
+    expect(customer.money).toBe(2750);
+  });
+
+  it('should fill only the amount the customer can afford', () => {
+    const customer = {
+      money: 180,
+      vehicle: {
+        maxTankCapacity: 40,
+        fuelRemains: 10,
+      },
+    };
+
+    fillTank(customer, 50, 10);
+
+    expect(customer.vehicle.fuelRemains).toBe(13.6);
+    expect(customer.money).toBe(0);
+  });
+
+  it('should round fuel down to one decimal place', () => {
+    const customer = {
+      money: 333,
+      vehicle: {
+        maxTankCapacity: 40,
+        fuelRemains: 10,
+      },
+    };
+
+    fillTank(customer, 50, 10);
+
+    expect(customer.vehicle.fuelRemains).toBe(16.6);
+    expect(customer.money).toBe(3);
+  });
+
+  it('should not fill fuel if rounded amount is less than 2 liters', () => {
+    const customer = {
+      money: 90,
+      vehicle: {
+        maxTankCapacity: 40,
+        fuelRemains: 10,
+      },
+    };
+
+    fillTank(customer, 50, 10);
+
+    expect(customer.vehicle.fuelRemains).toBe(10);
+    expect(customer.money).toBe(90);
+  });
+
+  it('should round fuel price to nearest hundredth', () => {
+    const customer = {
+      money: 100,
+      vehicle: {
+        maxTankCapacity: 40,
+        fuelRemains: 10,
+      },
+    };
+
+    fillTank(customer, 33.333, 3);
+
+    expect(customer.vehicle.fuelRemains).toBe(13);
+    expect(customer.money).toBe(0);
+  });
+
+  it('should not return anything', () => {
+    const customer = {
+      money: 3000,
+      vehicle: {
+        maxTankCapacity: 40,
+        fuelRemains: 8,
+      },
+    };
+
+    const result = fillTank(customer, 50, 10);
+
+    expect(result).toBeUndefined();
+  });
 });