Interview #27: Cucumber-How would you handle scenarios where steps need conditional logic (e.g., "If the user is logged in, then…")?

In Cucumber with Java, handling conditional logic within steps—like “If the user is logged in, then…”—can sometimes challenge the straightforward, readable nature of Behavior-Driven Development (BDD). Conditional logic in BDD tests should ideally be minimized to maintain clarity and readability, but there are several ways to address such needs when they arise. Here’s how I would approach handling scenarios with conditional steps in Cucumber for Java:

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1. Separate Scenarios to Avoid Conditional Logic

• The most straightforward approach is to split scenarios to cover all conditional cases explicitly. This avoids embedding conditional statements within step definitions, making each scenario clear and focused on a single behavior. By writing separate scenarios, we make it clear whether the user should be logged in or not, reducing ambiguity.

For example:

Scenario: Perform action when the user is logged in

Given the user is logged in

When the user performs the action

Then the expected outcome should occur

Scenario: Perform action when the user is not logged in

Given the user is not logged in

When the user attempts to perform the action

Then the outcome should handle unauthenticated users

• Structuring scenarios this way keeps each scenario focused on one specific flow and allows for more straightforward step definitions.

2. Using Background to Define Common Preconditions

• If multiple scenarios within a feature require the user to be in a logged-in state, the Background section in Gherkin can be used to set up the state, reducing redundancy.

For example:

Background: User is logged in

Given the user is logged in

Scenario: User performs first action

When the user performs the first action

Then the expected result should be achieved

Scenario: User performs second action

When the user performs the second action

Then the expected result should be achieved

• Using Background is ideal for simple, consistent conditions that apply to all scenarios in a feature file. However, if only some scenarios require a specific state, a different approach may be more effective.

3. Scenario Outline with Parameterized Login State

• For scenarios that vary slightly based on conditions (e.g., user login status), using a Scenario Outline with parameters is a clean solution. This allows us to define the conditional state directly in the Gherkin examples, which keeps the step definitions straightforward.

Example:

Scenario Outline: Perform action based on login state

Given the user is <login_state>

When the user performs the action

Then the outcome should be <expected_result>

Examples:

| login_state | expected_result |

| logged in | outcome for logged-in user |

| not logged in| outcome for logged-out user|

• In the step definition, we can then use the login_state parameter to determine the correct setup, handling the conditional logic once while keeping it clean and contained.

@Given("the user is {string}")

public void the_user_is(String loginState) {

if (loginState.equals("logged in")) {

loginUser();

} else {

logoutUser();

}

}

4. Tags for Conditional Setup and Execution

• Cucumber tags, such as @LoggedIn or @LoggedOut, can be used to set up specific conditions for different scenarios. In the step definitions or hooks, we can then determine behavior based on these tags.

For example:

@LoggedIn

Scenario: User performs action when logged in

When the user performs the action

Then the outcome should be the logged-in result

@LoggedOut

Scenario: User performs action when not logged in

When the user attempts to perform the action

Then the outcome should handle unauthenticated users

• In the Before hook, we can then implement conditional logic to set the required user state based on the tags.

@Before("@LoggedIn")

public void ensureUserIsLoggedIn() {

if (!isUserLoggedIn()) {

loginUser();

}

}

@Before("@LoggedOut")

public void ensureUserIsLoggedOut() {

if (isUserLoggedIn()) {

logoutUser();

}

}

• Using tags with hooks keeps scenarios themselves simple and focused on behaviors, and helps avoid conditional complexity within the step definitions.

5. Helper Methods for Conditional Logic in Step Definitions

• When scenarios cannot be fully separated and conditional logic within steps is unavoidable, helper methods can encapsulate the conditional checks. This approach allows conditional actions while keeping step definitions as clean and readable as possible.

For instance:

@Given("the user is logged in")

public void ensureUserIsLoggedIn() {

if (!isUserLoggedIn()) {

loginUser();

}

}

• This helper method, isUserLoggedIn(), keeps the actual step definition free from complex branching, ensuring the login state without exposing unnecessary details within the scenario.

6. Using Java Enums or Constants for State Management

• Using Enums or constants can help control and set up predefined states, especially when there are multiple possible conditions. For example, if a user has different roles (e.g., logged in as an admin, user, or guest), we can define an Enum to manage this.

Example Enum:

public enum UserState {

LOGGED_IN, LOGGED_OUT, ADMIN, GUEST

}

• In the step definitions, we could then switch based on these predefined states, making the conditions explicit and reusable across different steps.

@Given("the user is in {UserState} state")

public void setUserState(UserState state) {

switch (state) {

case LOGGED_IN:

loginUser();

break;

case LOGGED_OUT:

logoutUser();

break;

case ADMIN:

loginUserAsAdmin();

break;

case GUEST:

logoutUser();

break;

}

}

• This keeps conditions manageable and reusable, and it improves readability by clearly defining possible states.

7. Dynamic Step Definitions with Optional Parameters

• Java-based Cucumber supports step definitions with optional parameters, allowing you to add conditionals directly within the Gherkin steps. However, this approach should be used sparingly, as it can reduce the clarity of scenarios.

Example:

Scenario Outline: Conditional login step

Given the user <login_state>

When the user performs an action

Then the outcome should be as expected

Examples:

| login_state |

| logged in |

| not logged in |

• In the step definition:

@Given("the user {string}")

public void setUserLoginState(String loginState) {

if (loginState.equals("logged in")) {

loginUser();

} else {

logoutUser();

}

}

Summary

To handle scenarios with conditional logic in Cucumber for Java, I prioritize creating separate, clear scenarios to avoid embedding conditional logic whenever possible. Using Background sections, Scenario Outlines, and tags helps reduce complexity while preserving the readability of BDD scenarios. When conditions are unavoidable, helper methods, enums, and hooks provide ways to encapsulate logic cleanly. By following these approaches, I ensure that conditional scenarios remain maintainable, readable, and aligned with BDD’s goal of simple, behavior-focused documentation.