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42f853e May 30, 2018
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@pekkaklarck @Tattoo @TechieWidget @charleswhchan
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How to write good test cases using Robot Framework

Introduction

Naming

Test suite names

  • Suite names should be as descriptive as possible.
  • Names are created automatically from file or directory names:
    • Extensions are stripped.
    • Underscores are converted to spaces.
    • If name is all lower case, words are capitalized.
  • Names can be relatively long, but overly long names are not convenient for the file system.
  • The name of the top level suite can be overridden from the command line using the --name option if needed.

Examples:

  • login_tests.robot -> Login Tests
  • IP_v4_and_v6 -> IP v4 and v6

Test case names

  • Test names should be descriptive like the suite names.
  • If a suite contains many similar tests and is well named, test names can be shorter.
  • Name is exactly the same as you specified in the test case file without any conversion.

For example, if we have tests related to invalid login in a file invalid_login.robot, these would be OK test case names:

*** Test Cases ***
Empty Password
Empty Username
Empty Username And Password
Invalid Username
Invalid Password
Invalid Username And Password

These names would be somewhat long:

*** Test Cases ***
Login With Empty Password Should Fail
Login With Empty Username Should Fail
Login With Empty Username And Password Should Fail
Login With Invalid Username Should Fail
Login With Invalid Password Should Fail
Login With Invalid Username And Invalid Password Should Fail

Keyword names

  • Keyword names should be descriptive and clear.
  • Should explain what the keyword does, not how it does its task(s).
  • Very different abstraction levels (e.g. Input Text or Administrator logs into system).
  • There is no clear guideline on whether a keyword should be fully title cased or have only the first letter be capitalized.
    • Title casing is often used when the keyword name is short (e.g. Input Text).
    • Capitalizing just the first letter typically works better with keywords that are like sentences (e.g. Administrator logs into system). These type of keywords are often higher level.

Good:

*** Keywords ***
Login With Valid Credentials

Bad:

*** Keywords ***
Input Valid Username And Valid Password And Click Login Button

Naming setup and teardown

  • Try to use name that describes what is done.
    • Possibly use an existing keyword.
  • More abstract names are acceptable if a setup or teardown contains unrelated steps.
    • Listing steps in name is duplication and a maintenance problem (e.g. Login to system, add user, activate alarms and check balance).
    • Often better to use something generic (e.g. Initialize system).
  • BuiltIn keyword Run Keywords can work well if keywords implementing lower level steps already exist.
    • Not reusable so best used when the setup or teardown scenario is needed only once.
  • Everyone working with these tests should always understand what a setup or teardown does.

Good:

*** Settings ***
Suite Setup     Initialize System

Good (if only used once):

*** Settings ***
Suite Setup     Run Keywords
...             Login To System    AND
...             Add User           AND
...             Activate Alarms    AND
...             Check Balance

Bad:

*** Settings ***
Suite Setup     Login To System, Add User, Activate Alarms And Check Balance

Documentation

Test suite documentation

  • Often a good idea to add overall documentation to test case files.
  • Should contain background information, why tests are created, notes about execution environment, etc.
  • Do not just repeat test suite name.
    • Better to have no documentation if it is not really needed.
  • Do not include too much details about test cases.
    • Tests should be clear enough to understand alone.
    • Duplicate information is waste and maintenance problem.
  • Documentation can contain links to more information.
  • Consider using test suite metadata if you need to document information represented as name-value pairs (e.g. Version: 1.0 or OS: Linux).
  • Documentation and metadata of the top level suite can be set from the command line using --doc and --metadata options, respectively.

Good:

*** Settings ***
Documentation    Tests to verify that account withdrawals succeed and
...              fail correctly depending from users account balance
...              and account type dependent rules.
...              See http://internal.example.com/docs/abs.pdf
Metadata         Version    0.1

Bad (especially if suite is named well like account_withdrawal.robot):

*** Settings ***
Documentation    Tests Account Withdrawal.

Test case documentation

  • Test normally does not need documentation.
    • Name and possible documentation of the parent suite and test's own name should give enough background information.
    • Test case structure should be clear enough without documentation or other comments.
  • Tags are generally more flexible and provide more functionality (statistics, include/exclude, etc.) than documentation.
  • Sometimes test documentation is useful. No need to be afraid to use it.

Good:

*** Test Cases ***
Valid Login
    [Tags]    Iteration-3    Smoke
    Open Login Page
    Input Username    ${VALID USERNAME}
    Input Password    ${VALID PASSWORD}
    Submit Credentials
    Welcome Page Should Be Open

Bad:

*** Test Cases ***
Valid Login
    [Documentation]    Opens a browser to login url, inputs valid username
    ...                and password and checks that the welcome page is open.
    ...                This is a smoke test. Created in iteration 3.
    Open Browser    ${URL}    ${BROWSER}
    Input Text    field1    ${UN11}
    Input Text    field2    ${PW11}
    Click Button    button_12
    Title Should Be    Welcome Page

User keyword documentation

  • Not needed if keyword is relatively simple.
    • Good keyword, argument names and clear structure should be enough.
  • Important usage is documenting arguments and return values.
  • Shown in resource file documentation generated with Libdoc and editors such as RIDE can show it in keyword completion and elsewhere.

Test suite structure

  • Tests in a suite should be related to each other.
    • Common setup and/or teardown is often a good indicator.
  • Should not have too many tests (max 10) in one file unless they are data-driven tests.
  • Tests should be independent. Initialization using setup/teardown.
  • Sometimes dependencies between tests cannot be avoided.
    • For example, it can take too much time to initialize all tests separately.
    • Never have long chains of dependent tests.
    • Consider verifying the status of the previous test using the built-in ${PREV TEST STATUS} variable.

Test case structure

  • Test case should be easy to understand.
  • One test case should be testing one thing.
    • Things can be small (part of a single feature) or large (end-to-end).
  • Select suitable abstraction level.
    • Use abstraction level consistently (single level of abstraction principle).
    • Do not include unnecessary details on the test case level.
  • Two kinds of test cases:

Workflow tests

  • Generally have these phases:
    • Precondition (optional, often in setup)
    • Action (do something to the system)
    • Verification (validate results, mandatory)
    • Cleanup (optional, always in teardown to make sure it is executed)
  • Keywords describe what a test does.
    • Use clear keyword names and suitable abstraction level.
    • Should contain enough information to run manually.
    • Should never need documentation or commenting to explain what the test does.
  • Different tests can have different abstraction levels.
    • Tests for a detailed functionality are more precise.
    • End-to-end tests can be on very high level.
    • One test should use only one abstraction level
  • Different styles:
    • More technical tests for lower level details and integration tests.
    • "Executable specifications" act as requirements.
    • Use domain language.
    • Everyone (including customer and/or product owner) should always understand.
  • No complex logic on the test case level.
    • No for loops or if/else constructs.
    • Use variable assignments with care.
    • Test cases should not look like scripts!
  • Max 10 steps, preferably less.

Example using "normal" keyword-driven style:

*** Test Cases ***
Valid Login
    Open Browser To Login Page
    Input Username    demo
    Input Password    mode
    Submit Credentials
    Welcome Page Should Be Open

Example using higher level "gherkin" style:

*** Test Cases ***
Valid Login
    Given browser is opened to login page
    When user "demo" logs in with password "mode"
    Then welcome page should be open

See the web demo project for executable versions of the above examples.

Data-driven tests

  • One high-level keyword per test.
    • Different arguments create different tests.
    • One test can run the same keyword multiple times to validate multiple related variations
  • If the keyword is implemented as a user keyword, it typically contains a similar workflow as workflow tests.
    • Unless needed elsewhere, it is a good idea to create it in the same file as tests using it.
  • Recommended to use the test template functionality.
    • No need to repeat the keyword multiple times.
    • Easier to test multiple variations in one test.
  • Possible, and recommended, to name column headings
  • If a really big number of tests is needed, consider generating them based on an external model.

Example:

*** Settings ***
Test Template         Login with invalid credentials should fail

*** Test Cases ***    USERNAME             PASSWORD
Invalid Username      invalid              ${VALID PASSWORD}
Invalid Password      ${VALID USERNAME}    invalid
Invalid Both          invalid              invalid
Empty Username        ${EMPTY}             ${VALID PASSWORD}
Empty Password        ${VALID USERNAME}    ${EMPTY}
Empty Both            ${EMPTY}             ${EMPTY}

*** Keywords ***
Login with invalid credentials should fail
    [Arguments]    ${username}    ${password}
    Input Username    ${username}
    Input Password    ${password}
    Submit Credentials
    Error Page Should Be Open

The web demo project contains an executable version of this example too.

User keywords

  • Should be easy to understand.
    • Same rules as with workflow tests.
  • Different abstraction levels.
  • Can contain some programming logic (for loops, if/else).
    • Especially on lower level keywords.
    • Complex logic in libraries rather than in user keywords.

Variables

  • Encapsulate long and/or complicated values.
  • Pass information from them command line using the --variable option.
  • Pass information between keywords.

Variable naming

  • Clear but not too long names.
  • Can use comments in variable table to document them more.
  • Use case consistently:
    • Lower case with local variables only available inside a certain scope.
    • Upper case with others (global, suite or test level).
    • Both space and underscore can be used as a word separator.
  • Recommended to also list variables that are set dynamically in the variable table.
    • Set typically using BuiltIn keyword Set Suite Variable.
    • The initial value should explain where/how the real value is set.

Example:

*** Settings ***
Suite Setup       Set Active User

*** Variables ***
# Default system address. Override when tested agains other instances.
${SERVER URL}     http://sre-12.example.com/
${USER}           Actual value set dynamically at suite setup

*** Keywords ***
Set Active User
    ${USER} =    Get Current User    ${SERVER URL}
    Set Suite Variable    ${USER}

Passing and returning values

  • Common approach is to return values from keywords, assign them to variables and then pass them as arguments to other keywords.
    • Clear and easy to follow approach.
    • Allows creating independent keywords and facilitates re-use.
    • Looks like programming and thus not so good on the test case level.
  • Alternative approach is storing information in a library or using the BuiltIn Set Test Variable keyword.
    • Avoid programming style on the test case level.
    • Can be more complex to follow and make reusing keywords harder.

Good:

*** Test Cases ***
Withdraw From Account
    Withdraw From Account    $50
    Withdraw Should Have Succeeded

*** Keywords ***
Withdraw From Account
    [Arguments]    ${amount}
    ${STATUS} =    Withdraw From User Account    ${USER}    ${amount}
    Set Test Variable    ${STATUS}

Withdraw Should Have Succeeded
    Should Be Equal    ${STATUS}   SUCCESS

Not so good:

*** Test Cases ***
Withdraw From Account
    ${status} =    Withdraw From Account    $50
    Withdraw Should Have Succeeded    ${status}

*** Keywords ***
Withdraw From Account
    [Arguments]    ${amount}
    ${status} =    Withdraw From User Account    ${USER}    ${amount}
    [Return]    ${status}

Withdraw Should Have Succeeded
    [Arguments]    ${status}
    Should Be Equal     ${status}    SUCCESS

Avoid sleeping

  • Sleeping is a very fragile way to synchronize tests.
  • Safety margins cause too long sleeps on average.
  • Instead of sleeps, use keyword that polls has a certain action occurred.
    • Keyword names often starts with Wait ....
    • Should have a maximum time to wait.
    • Possible to wrap other keywords inside the BuiltIn keyword Wait Until Keyword Succeeds.
  • Sometimes sleeping is the easiest solution.
    • Always use with care.
    • Never use in user keywords that are used often by tests or other keywords.
  • Can be useful in debugging to stop execution.