Modify `ApiHelpers` spec to adhere to the Four-Phase test style.

- Use whitespace to separate the setup, expectation and teardown phases.

spec/requests/api/helpers_spec.rb

@@ -97,20 +97,26 @@ describe API::Helpers, api: true do
       it "returns nil for an invalid token" do
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = 'invalid token'
         allow_any_instance_of(self.class).to receive(:doorkeeper_guard){ false }
+
         expect(current_user).to be_nil
       end
 
       it "returns nil for a user without access" do
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = user.private_token
         allow_any_instance_of(Gitlab::UserAccess).to receive(:allowed?).and_return(false)
+
         expect(current_user).to be_nil
       end
 
       it "leaves user as is when sudo not specified" do
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = user.private_token
+
         expect(current_user).to eq(user)
+
         clear_env
+
         params[API::APIGuard::PRIVATE_TOKEN_PARAM] = user.private_token
+
         expect(current_user).to eq(user)
       end
     end
@@ -124,12 +130,14 @@ describe API::Helpers, api: true do
 
       it "returns nil for an invalid token" do
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = 'invalid token'
+
         expect(current_user).to be_nil
       end
 
       it "returns nil for a user without access" do
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = personal_access_token.token
         allow_any_instance_of(Gitlab::UserAccess).to receive(:allowed?).and_return(false)
+
         expect(current_user).to be_nil
       end
 
@@ -137,6 +145,7 @@ describe API::Helpers, api: true do
         personal_access_token = create(:personal_access_token, user: user, scopes: ['read_user'])
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = personal_access_token.token
         allow_access_with_scope('write_user')
+
         expect(current_user).to be_nil
       end
 
@@ -145,18 +154,21 @@ describe API::Helpers, api: true do
         expect(current_user).to eq(user)
         clear_env
         params[API::APIGuard::PRIVATE_TOKEN_PARAM] = personal_access_token.token
+
         expect(current_user).to eq(user)
       end
 
       it 'does not allow revoked tokens' do
         personal_access_token.revoke!
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = personal_access_token.token
+
         expect(current_user).to be_nil
       end
 
       it 'does not allow expired tokens' do
         personal_access_token.update_attributes!(expires_at: 1.day.ago)
         env[API::APIGuard::PRIVATE_TOKEN_HEADER] = personal_access_token.token
+
         expect(current_user).to be_nil
       end
     end