Before(:Each) for All Tests Except One

before(:each) for all tests except one

You can add metadata to tests that do not need to login, then evaluate that metadata in your before hook.

For example, two tests in the same file. One needs to login and one does not.

# foo_spec.rb
describe Foo do
  describe "#bar" do
    it "needs to log in" do
      expect(1).to eq 1
    end
  end
  describe "#baz" do
    it "needs to not log in", :logged_out do
      expect(1).to eq 1
    end
  end
end

So we added metadata to our it block. Next, we configure the before hook to evaluate the example's metadata.

config.before(:each) do |test|
  login(email, password) unless test.metadata[:logged_out]
  visit root_url
end

Now, each test will visit root_url but only the ones not tagged with :logged_out will call login.

RSpec calls these metadata based hooks filters. You can learn a bit more about them here.

How to deal with @BeforeEach @AfterEach for all test except one

If moving the test to another class is not practical, you can use a @Nested class to solve this. @BeforeEach and @AfterEach will be executed only for those tests defined inside. Here is an example:

@Test
void oneTEstWithNoBeforeAfterEach() {}

@Nested
class allOtherTestsGoHere {

    @BeforeEach
    void setUp() {}

    @AfterEach
    void tearDown() {}

    @Test
    void testOne() {}

    @Test
    void testTwo() {}
}

rails rspec before all vs before each

before(:all) runs the block one time before all of the examples are run.

before(:each) runs the block one time before each of your specs in the file

before(:all) sets the instance variables @admission, @project, @creative, @contest_entry one time before all of the it blocks are run.

However, :before(:each) resets the instance variables in the before block every time an it block is run.

Its a subtle distinction but important

again,

before(:all)
#before block is run
it { should belong_to(:owner).class_name('User') }
it { should belong_to(:project) }
it { should have_many(:entry_comments) }

it { should validate_presence_of(:owner) }
it { should validate_presence_of(:project) }
it { should validate_presence_of(:entry_no) }
it { should validate_presence_of(:title) }

before(:each)
# before block
it { should belong_to(:owner).class_name('User') }
# before block
it { should belong_to(:project) }
# before block
it { should have_many(:entry_comments) }
# before block

# before block
it { should validate_presence_of(:owner) }
# before block
it { should validate_presence_of(:project) }
# before block
it { should validate_presence_of(:entry_no) }
# before block
it { should validate_presence_of(:title) }

In what order does beforeEach and beforeAll execute?

You can read this article https://jestjs.io/docs/en/setup-teardown.html on Jest document.

beforeAll(() => console.log('1 - beforeAll'));
afterAll(() => console.log('1 - afterAll'));
beforeEach(() => console.log('1 - beforeEach'));
afterEach(() => console.log('1 - afterEach'));
test('', () => console.log('1 - test'));
describe('Scoped / Nested block', () => {
  beforeAll(() => console.log('2 - beforeAll'));
  afterAll(() => console.log('2 - afterAll'));
  beforeEach(() => console.log('2 - beforeEach'));
  afterEach(() => console.log('2 - afterEach'));
  test('', () => console.log('2 - test'));
});

// 1 - beforeAll
// 1 - beforeEach
// 1 - test
// 1 - afterEach
// 2 - beforeAll
// 1 - beforeEach
// 2 - beforeEach
// 2 - test
// 2 - afterEach
// 1 - afterEach
// 2 - afterAll
// 1 - afterAll

As you can see, beforeAll will be run before all of your test be executed. beforeEach will be run before each of you test. So beforeAll will be run before beforeEach

BeforeAll vs. BeforeEach. When to use them?

Both are used to set up whatever conditions are needed for one or more tests.

If you're certain that the tests don't make any changes to those conditions, you can use beforeAll (which will run once).

If the tests do make changes to those conditions, then you would need to use beforeEach, which will run before every test, so it can reset the conditions for the next one.

Unless the initialization is slow or computationally expensive, it may be safest to default to using beforeEach as it reduces the opportunity for human error, i.e. not realizing that one test is changing the setup for the next one.

The sample you showed is a good example of using both in combination -- the slow network call is put in beforeAll, so it only has to happen once; and the data object (which is presumably modified by the tests) is reset each time in beforeEach.

Difference between @Before, @BeforeClass, @BeforeEach and @BeforeAll

The code marked @Before is executed before each test, while @BeforeClass runs once before the entire test fixture. If your test class has ten tests, @Before code will be executed ten times, but @BeforeClass will be executed only once.

In general, you use @BeforeClass when multiple tests need to share the same computationally expensive setup code. Establishing a database connection falls into this category. You can move code from @BeforeClass into @Before, but your test run may take longer. Note that the code marked @BeforeClass is run as static initializer, therefore it will run before the class instance of your test fixture is created.

In JUnit 5, the tags @BeforeEach and @BeforeAll are the equivalents of @Before and @BeforeClass in JUnit 4. Their names are a bit more indicative of when they run, loosely interpreted: 'before each tests' and 'once before all tests'.

What is the difference between `before()` and `beforeEach()`?

before() is run once before all the tests in a describe
after()   is run once after all the tests in a describe
beforeEach() is run before each test in a describe
afterEach()   is run after each test in a describe

Which one you want to use depends on your actual test.

Now, for the long explanation. If you run mocha -R min on this:

describe("top", function () {
    before(function () {
        console.log("top before");
    });
    after(function () {
        console.log("top after");
    });
    beforeEach(function () {
        console.log("top beforeEach");
    });
    afterEach(function () {
        console.log("top afterEach");
    });
    it("test1", function () {
        console.log("top test1");
    });
    describe("sublevel", function() {
        before(function () {
            console.log("sublevel before");
        });
        after(function () {
            console.log("sublevel after");
        });
        beforeEach(function () {
            console.log("sublevel beforeEach");
        });
        afterEach(function () {
            console.log("sublevel afterEach");
        });
        it("test1", function () {
            console.log("sublevel test1");
        });
        it("test2", function () {
            console.log("sublevel test2");
        });
    });
    it("test2", function () {
        console.log("top test2");
    });
});

You'll see something like (I've omitted the output that is not relevant):

top before
top beforeEach
top test1
top afterEach
top beforeEach
top test2
top afterEach
sublevel before
top beforeEach
sublevel beforeEach
sublevel test1
sublevel afterEach
top afterEach
top beforeEach
sublevel beforeEach
sublevel test2
sublevel afterEach
top afterEach
sublevel after
top after

The thing that may be surprising if you look at what executes before and after each of the tests at the sublevel is that both the beforeEach callbacks at the top level and at the sublevel are called. Same thing for the afterEach.

Some are also surprised by the sequence sublevel before, top beforeEach, sublevel beforeEach. They think that all the hooks in an outer scope should execute before all the hooks in an inner scope, so they expect the sequence: top beforeEach, sublevel before, sublevel beforeEach. However, the order in which Mocha executes the hooks makes complete sense: a before hook is meant to set the stage for a group of tests, whereas a beforeEach test is for each individual tests. When Mocha executes a test, all the before and the beforeEach hooks that were set in the describe that contains it, and all the ancestors of that describe apply to the test. Mocha will execute each before hook from the outermost scope to the innermost, and all beforeEach hook from the outermost scope to the innermost. However, all before hooks that apply are executed before any beforeEach hook. This explains the order above: sublevel before executes before top beforeEach because it is a before hook. And with after and afterEach, the same logic applies but the the order is reversed: all afterEach hooks that apply are executed before any after hook.

Also notice that Mocha does not care about how I ordered my it calls relative to the describe call in the top level describe. It executes top test1, top test2 and then the sublevel tests, even though the order I gave was top test1, then the sublevel tests and then top test2.

What you want to use among before, beforeEach, etc. really depends on the specifics of your tests. If you need to setup a mock object or data structure and this object or structure can be reused by all the tests in a single describe, you can use before to set it up, and after to tear it down. This could be the case if you are doing read-only tests on the structure. If all your tests only read it, then there is no need to create it over and over. If each test in your describe needs a new copy of the structure because each test is modifying the structure then you should use beforeEach to create the structure anew for each test and then afterEach if you need to tear it down cleanly. Doing this ensures test isolation: each test starts from a known state and does not depend on the presence or absence of a previous test to succeed.

Can I exclude an individual test from @BeforeEach in JUnit5?

You can move the tests that require the before-each behaviour into an inner ˋ@Nested´ subclass and put the before-each method there.

public class MyClassTest {

     @Test
     void test1(){}
     
     @Nested
     private class NestedTestBlock {
      
      @BeforeEach
      void beforeEach(){}
    
      @Test
      void test2() {}
    
      @Test
      void test3() {}
     }
    
}

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