TDD anti patterns - episode 4 - with Javier Martínez

Transcript

TDD - EP 4 codurance.com Testing anti-patterns - The greedy

catcher, The sequencer, Hidden dependency and The enumerator

Matheus Marabesi Hello there, you can call me Marabesi, But

my name is Matheus Marabesi, I work at Codurance as a Software Craftsperson. I enjoy talking about anything related to: testing, patterns and gamiﬁcation. You can ﬁnd me at @MatheusMarabesi or https://marabesi.com Codurance Crafting Code

1. Intro - Recap 2. The greedy catcher 3. The

sequencer 4. Hidden dependency 5. The enumerator 6. Wrapping up Crafting code Agenda

1. Recap Episode 1, Episode 2, Episode 3 Getting started

The Liar The Giant The Mockery The Inspector Generous Leftovers

The Local Hero The Nitpicker The Secret Catcher The Dodger The Loudmouth Anti patterns The Greedy Catcher Excessive Setup The Sequencer Hidden Dependency The Enumerator The Stranger The Operating System Evangelist Success Against All Odds The Free Ride The One The Peeping Tom The Slow Poke James Carr - TDD Anti-Patterns

The Liar 4 The Giant 5 The Mockery The Inspector

Generous Leftovers The Local Hero The Nitpicker The Secret Catcher The Dodger The Loudmouth Anti patterns The Greedy Catcher Excessive Setup 3 The Sequencer Hidden Dependency The Enumerator The Stranger The Operating System Evangelist Success Against All Odds The Free Ride The One The Peeping Tom The Slow Poke 6

Anti patterns - Survey takeaways 1. Survey notes: Javascript, PHP

and Java were the most used programming languages 2. Survey notes: Practitioners usually informally learn TDD 3. The anti patterns covered were related to test last 4. Subjects we touched around testability: SOLID, Object calisthenics, Non-determinism and the test pyramid

2. Anti-patterns - Episode 4 The greedy catcher, The sequencer,

Hidden dependency and The enumerator Getting started

The Liar The Giant The Mockery The Inspector Generous Leftovers

The Local Hero The Nitpicker The Secret Catcher The Dodger The Loudmouth Anti patterns The Greedy Catcher Excessive Setup The Sequencer Hidden Dependency The Enumerator The Stranger The Operating System Evangelist Success Against All Odds The Free Ride The One The Peeping Tom The Slow Poke James Carr - TDD Anti-Patterns

The Liar The Giant The Mockery The Inspector Generous Leftovers

The Local Hero The Nitpicker The Secret Catcher The Dodger The Loudmouth Anti patterns The Greedy Catcher 8 Excessive Setup The Sequencer 8 Hidden Dependency 2 The Enumerator 9 The Stranger The Operating System Evangelist Success Against All Odds The Free Ride The One The Peeping Tom The Slow Poke James Carr - TDD Anti-Patterns

Challenge time Crafting code Which one if faster to understand?

describe('Request.headers', function () { it('should work', async () => {

const { page, server, isChrome } = getTestState(); const response = await page.goto(server.EMPTY_PAGE); if (isChrome) expect(response.request().headers()['user-agent']).toContain('Chrome'); else expect(response.request().headers()['user-agent']).toContain('Firefox'); }); }); describe('Request.headers', function () { itChromeOnly('should define Chrome as user agent header', async () => { const { page, server } = getTestState(); const response = await page.goto(server.EMPTY_PAGE); expect(response.request().headers()['user-agent']).toContain('Chrome'); }); itFirefoxOnly('should define Firefox as user agent header', async () => { const { page, server } = getTestState(); const response = await page.goto(server.EMPTY_PAGE); expect(response.request().headers()['user-agent']).toContain('Firefox'); }); }); Puppeteer A

describe('Request.headers', function () { it('should work', async () => {

const { page, server, isChrome } = getTestState(); const response = await page.goto(server.EMPTY_PAGE); if (isChrome) expect(response.request().headers()['user-agent']).toContain('Chrome'); else expect(response.request().headers()['user-agent']).toContain('Firefox'); }); }); describe('Request.headers', function () { itChromeOnly('should define Chrome as user agent header', async () => { const { page, server } = getTestState(); const response = await page.goto(server.EMPTY_PAGE); expect(response.request().headers()['user-agent']).toContain('Chrome'); }); itFirefoxOnly('should define Firefox as user agent header', async () => { const { page, server } = getTestState(); const response = await page.goto(server.EMPTY_PAGE); expect(response.request().headers()['user-agent']).toContain('Firefox'); }); }); Puppeteer B

describe('Request.headers', function () { it('should work', async () => {

const { page, server, isChrome } = getTestState(); const response = await page.goto(server.EMPTY_PAGE); if (isChrome) expect(response.request().headers()['user-agent']).toContain('Chrome'); else expect(response.request().headers()['user-agent']).toContain('Firefox'); }); }); describe('Request.headers', function () { itChromeOnly('should define Chrome as user agent header', async () => { const { page, server } = getTestState(); const response = await page.goto(server.EMPTY_PAGE); expect(response.request().headers()['user-agent']).toContain('Chrome'); }); itFirefoxOnly('should define Firefox as user agent header', async () => { const { page, server } = getTestState(); const response = await page.goto(server.EMPTY_PAGE); expect(response.request().headers()['user-agent']).toContain('Firefox'); }); }); Puppeteer A B

• Could you spot something that seems to be a

smell? Anti-patterns?

• Could you spot something that seems to be a

smell? • Were there anti patterns? Anti-patterns?

2. The greedy catcher - 🏆 8 Crafting code

2. The greedy catcher - 🏆 8 A unit test

which catches exceptions and swallows the stack trace, sometimes replacing it with a less informative failure message, but sometimes even just logging (c.f. Loudmouth) and letting the test pass. Crafting code

public function test_retrieve_the_latest_payment_for_a_subscription() { $user = $this->createCustomer('retrieve_the_latest_payment_for_a_subscription'); try { $user->newSubscription('main',

static::$priceId)->create('pm_card_threeDSecure2Required'); $this->fail('Expected exception '.IncompletePayment::class.' was not thrown.'); } catch (IncompletePayment $e) { $subscription = $user->refresh()->subscription('main'); $this->assertInstanceOf(Payment::class, $payment = $subscription->latestPayment()); $this->assertTrue($payment->requiresAction()); } } PHP - Laravel/Cashier stripe

public function test_retrieve_the_latest_payment_for_a_subscription() { $user = $this->createCustomer('retrieve_the_latest_payment_for_a_subscription'); try { $user->newSubscription('main',

try { const token = jwt_decode(req?.cookies['token']); if (token) { return

null; } else { return await logout($auth, redirect); } } catch (e) { return await logout($auth, redirect); } Jest

try { const token = jwt_decode(req?.cookies['token']); if (token) { return

it('should logout when token is invalid', async () => {

const redirect = jest.fn(); const serverParameters: Partial<IContextCookie> = { route: currentRoute as Route, $auth, redirect }; await actions.nuxtServerInit( actionContext as ActionContext, serverParameters as IContextCookie ); expect($auth.logout).toHaveBeenCalled(); }); Jest

it('should logout when token is invalid', async () => {

None

Secret catcher, silent catcher Relates to

3. The sequencer - 🏆8 Crafting code

3. The sequencer - 🏆8 A unit test that depends

on items in an unordered list appearing in the same order during assertions. Crafting code

test(contains three fruits', () => { const expectedFruits = ['banana',

'mango', 'watermelon'] expect(expectedFruits[0]).toEqual('banana') expect(expectedFruits[1]).toEqual('mango') expect(expectedFruits[2]).toEqual('watermelon') }) test('contains three fruits', () => { const expectedFruits = ['banana', 'mango', 'watermelon'] const actualFruits = ['banana', 'mango', 'watermelon'] expect(expectedFruits).toEqual( expect.arrayContaining(actualFruits) ) }) Jest - arrays / primitives

test(contains three fruits', () => { const expectedFruits = ['banana',

'mango', 'watermelon'] expect(expectedFruits[0]).toEqual('banana') expect(expectedFruits[1]).toEqual('mango') expect(expectedFruits[2]).toEqual('watermelon') }) test('contains three fruits', () => { const expectedFruits = ['mango', 'watermelon', 'banana'] const actualFruits = ['banana', 'mango', 'watermelon'] expect(expectedFruits).toEqual( expect.arrayContaining(actualFruits) ) }) Jest - arrays / primitives

def test_predictions_returns_a_dataframe_with_automatic_predictions(self,form): # Given order_id = "51a64e87-a768-41ed-b6a5-bf0633435e20" order_info = pd.DataFrame({"order_id":

[order_id], "form": [form],}) file_path = Path("tests/data/prediction_data.csv") service = FileRepository(file_path) # When result = get_predictions(main_service=service, order_info=order_info) # Then assert list(result.columns) == ["id", "quantity", "country", "form", "order_id"] Python

def test_predictions_returns_a_dataframe_with_automatic_predictions(self,form): # Given order_id = "51a64e87-a768-41ed-b6a5-bf0633435e20" order_info = pd.DataFrame({"order_id":

tests/test_predictions.py::TestPredictions::test_predictions_returns_a_dataframe_with_automatic_pr edictions FAILED [100%] tests/test_predictions.py:16 (TestPredictions.test_predictions_returns_a_dataframe_with_automatic_predictions) ['id', 'quantity', 'form', 'country',

'order_id'] != ['id', 'quantity', 'country', 'form', 'order_id'] Expected :['id', 'quantity', 'country', 'form', 'order_id'] Actual :['id', 'quantity', 'form', 'country', 'order_id'] Python

def test_predictions_returns_a_dataframe_with_automatic_predictions(self,form): # Given order_id = "51a64e87-a768-41ed-b6a5-bf0633435e20" order_info = pd.DataFrame({"order_id":

[order_id], "form": [form],}) file_path = Path("tests/data/prediction_data.csv") service = FileRepository(file_path) # When result = get_predictions(main_service=service, order_info=order_info) # Then assert ("id" in result.columns and "quantity" in result.columns and "country" in result.columns and "form" in result.columns and "order_id" in result.columns) Python

def test_predictions_returns_a_dataframe_with_automatic_predictions(self,form): # Given order_id = "51a64e87-a768-41ed-b6a5-bf0633435e20" order_info = pd.DataFrame({"order_id":

[order_id], "form": [form],}) file_path = Path("tests/data/prediction_data.csv") service = FileRepository(file_path) # When result = get_predictions(main_service=service, order_info=order_info) # Then assert set(result.columns) == {"id", "quantity", "country", "form", "order_id"} Python

Points of attention • Know your data structures • Think

about the role the order plays in a collection

4. Hidden dependency - 🏆2 Crafting code

4. Hidden dependency - 🏆2 A unit test that requires

some existing data to have been populated somewhere before the test runs. If that data wasn’t populated, the test will fail and leave little indication to the developer what it wanted, or why… forcing them to dig through acres of code to ﬁnd out where the data it was using was supposed to come from. Crafting code

query: str = """ select product.id po.order_id, po.quantity, product.country from

product join purchased as pur on pur.product_id = product.id join purchased_order as po on po.purchase_id = cur.id where product.completed is true and pur.type = 'MANUAL' and product.is_test is true ; """ Python

def test_dbdatasource_is_able_to_load_products_related_only_to_manual_purchase( self, db_resource ): # Given config_file_path = Path("./tests/data/configs/docker_config.json")

expected_result = pd.read_csv("./tests/data/manual_product_info.csv") datasource = DBDataSource(config_file_path=config_file_path) # When result = datasource.get_manual_purchases() # Then assert result.equals(expected_result) Python

def test_dbdatasource_is_able_to_load_products_related_only_to_manual_purchase( self, db_resource ): # Given config_file_path = Path("./tests/data/configs/docker_config.json")

E assert False E + where False = <bound method

NDFrame.equals of product_id ... country\n0 851799e1-9b28-4210-5c44-30ddf031ad20 ... 652400 181\n\n[1 rows x 5 columns]>( product_id ... country\n0 2893abc0-eab0-7223-a73d-e39060a7eabe ... 652400 099\n1 4760ff15-52af-1638-0c61-0ebecefc3eb0 ... 652400 130\n2 328f6852-9bf1-e1ce-cf44-8f680537adc6 ... 652400 148\n3 851799e1-9b28-4210-5c44-30ddf031ad20 ... 652400 181\n4 00ab74ed-bd99-63af-ca0c-4f10c8c090db ... 652400 249\n5 2893abc0-eab0-7223-a73d-e39060a7eabe ... 652400 099\n6 4760ff15-52af-1638-0c61-0ebecefc3eb0 ... 652400 130\n7 328f6852-9bf1-e1ce-cf44-8f680537adc6 ... 652400 148\n8 851799e1-9b28-4210-5c44-30ddf031ad20 ... 652400 181\n9 00ab74ed-bd99-63af-ca0c-4f10c8c090db ... 652400 249\n\n[10 rows x 5 columns]) E + where <bound method NDFrame.equals of product_id ... country\n0 851799e1-9b28-4210-5c44-30ddf031ad20 ... 652400 181\n\n[1 rows x 5 columns]> = fragrance_id ... country\n0 851799e1-9b28-4210-5c44-30ddf031ad20 ... 652400 181\n\n[1 rows x 5 columns].equals Python

is_test boolean DEFAULT false NOT NULL … and we forgot

to fulfill it.. Python

it('should list admins in the administrator field to be able

to pick one up', async () => { const store = Store(); const { findByTestId, getByText } = render(AdminPage as any, { store, mocks: { $route: { query: {}, }, }, }); await fireEvent.click(await findByTestId('admin-list')); await waitFor(() => { expect(getByText('Admin')).toBeInTheDocument(); }); }); Jest

it('should list admins in the administrator field to be able

export const Store = () => ({ modules: { user:

{ namespaced: true, state: { currentAdmin: { email: '[email protected]', }, }, getters: userGetters, }, admin: adminStore(adminList).modules.admin, }, }); Jest

export const Store = () => ({ modules: { user:

{ namespaced: true, state: { currentAdmin: { email: '[email protected]', }, }, getters: userGetters, }, admin: adminStore(adminList).modules.admin, }, }); Jest

it('should list admins in the administrator field to be able

to pick one up', async () => { const store = Store({ admin: { name: 'Admin' } }); const { findByTestId, getByText } = render(AdminPage as any, { store, mocks: { $route: { query: {}, }, }, }); await fireEvent.click(await findByTestId('admin-list')); await waitFor(() => { expect(getByText('Admin')).toBeInTheDocument(); }); }); Jest

• Use some libraries that generates fake data • Test

data adapters as soon as possible • If possible try to avoid data from external sources Points of attention

5. The enumerator - 🏆9 Crafting code

5. The enumerator - 🏆9 A unit test with each

test case method name is only an enumeration, i.e. test1, test2, test3. As a result, the intention of the test case is unclear, and the only way to be sure is to read the test case code and pray for clarity. Crafting code

from status_processor import StatusProcessor def test_set_status(): row_with_status_inactive_1 = dict( row_with__status_inactive_2

= dict( row_with_status_inactive_3 = dict( row_with_status_inactive_3b = dict( row_with_status_inactive_4 = dict( row_with_status_inactive_5 = dict( The enumerator - Python

from status_processor import StatusProcessor def test_set_status(): row_with_status_inactive_1 = dict( row_with__status_inactive_2

The enumerator - typescript + php

• Are we using 1, 2, 3? • The test

that failed was easy to understand why? Points of attention

6. Wrapping up We are almost done! Crafting code

• The Greedy Catcher • The Sequencer • Hidden Dependency

• The Enumerator • and many more! What we covered

https://www.codurance.com/publications/building-testing-culture https://www.codurance.com/publications/tdd-anti-patterns-chapter-1

https://www.codurance.com/publications/building-testing-culture https://www.codurance.com/publications/building-testing-culture

Matheus Marabesi Hello there, you can call me Marabesi, But

my name is Matheus Marabesi, I work at Codurance as a Software craftsperson. I enjoy talking about anything related to: testing, patterns and gamiﬁcation. You can ﬁnd me at @MatheusMarabesi or https://marabesi.com Codurance Crafting Code

TDD anti patterns - episode 4 - with Javier Martínez

TDD anti patterns - episode 4 - with Javier Martínez

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