Conjugation in Given When Then Gherkin Steps

There are no hard and fast rules when it comes to writing Gherkin scenarios. Nonetheless, following the past-present-conditional tense structure is typically seen as good practice.

Given

Given statements are passive and set up a context or condition for the entire scenario. They indicate that something already happened and might still be taking place.

Given User navigated to the login page (past tense)
Given User is on the login page (present continuous)
Given User has been granted admin privileges (perfect tense)

The exact tense to use is up to you!

When

When statements are active and indicate that an event is occurring. Naturally, this means the present tense should be used.

When User enters their username and password (present tense)
When User clicks "Log in" (present tense)

Then

Then statements are passive and indicate an expected yet uncertain outcome, state or behaviour.

Then User should be logged into website (conditional tense)

The keyword should is quite suited to indicate this sentiment.