Binding Script Functions to Test Steps

When you command TestComplete to run a BDD scenario, it runs script functions associated with test steps of this scenario:

To determine which script function to use for a test step, you use binding expressions in your code. You specify them before the script function. The expression syntax depends on the scripting language you use in your project:

As you can see, the binding expression includes the step type (Given, When, Then) and a substring that matches the test step description. The And and But steps should use the Given, When, or Then type depending on the step type they belong to.

• When searching for a script function to use, TestComplete compares the test step description in the BDD scenario and the substring in the binding expression. The substring and description should match.

• If TestComplete fails to find the matching script function, it posts an error message to the test log.

• If it finds several script functions matching the same test step, it posts an error message to the log as well.

In the simplest case, the linking substring coincides with the test step description. TestComplete also supports {arg} placeholders for parameters and regular expressions in substrings.

Test step description

Regular expressions

To use the same script function for different test steps, you can mark varying parts of step descriptions with regular expressions. For example:

JavaScript, JScript

Python

VBScript

DelphiScript

C++Script, C#Script

Copy Code

JavaScript, JScript

When("I enter .* and .*", function (){
  // ...
});

Python

@when("I enter .* and .*")
def step_impl():
  # ...

VBScript

' [When I enter .* and .*]
Sub I_enter_john1_and_password2
  ' ...
End Sub

DelphiScript

  // DelphiScript does not support BDD tests.

C++Script, C#Script

When("I enter .* and .*", function (){
  // ...
});

To extract some part of a step description and pass it to the script function as a parameter, enclose the regular expression in braces:

JavaScript, JScript

Python

VBScript

DelphiScript

C++Script, C#Script

Copy Code

JavaScript, JScript

// Note that use of braces and parameters
When("I enter (.*) and (.*)", function (param1, param2){
  // ...
});

Python

# Note that use of braces and parameters
@when("I enter (.*) and (.*)")
def step_impl(param1, param2):
  # ...

VBScript

' Note that use of braces and parameters
' [When I enter (.*) and (.*)]
Sub I_enter_and(param1, param2)
  ' ...
End Sub

DelphiScript

// DelphiScript does not support BDD tests.

C++Script, C#Script

// Note that use of braces and parameters
When("I enter (.*) and (.*)", function (param1, param2){
  // ...
});

The examples above use the .* expression to designate an arbitrary substring: the . token (period) matches any character, and * (asterisk) matches any number of repetitions. Below are examples of some frequently-used tokens:

Some frequently-used tokens

Some frequently-used tokensSome frequently-used tokens

Token	Description
.	Any single character except for the newline symbol.
*	Repeats the preceding expression 0 or more times. For example, a* matches a substring of a character of any length (a, aaa, aaaaa). .* matches an arbitrary substring.
?	Repeats the preceding expression 0 or 1 time. For example, ab?c matches ac and abc, but not abbc.
+	Repeats the preceding expression 1 or more times. For example, ab+c matches abc, abbc or abbbc, but not ac.
\d	Any digit. For instance, enter \d\d matches enter 10 and enter 29, but not enter abc.
[abc]	Any of the specified characters. For example, abc[de] matches both abcd and abce, but not abcf.
[a-z]	Any characters in the specified range. For example, a[b-e]h matches abh and adh, but not azh or abceh. a[b-e]*h matches abceh (that is, any sequence of the b-e characters between a and h).
[^abc] or [^a-z]	Any symbol except for those specified in brackets. For example, a[^0-9]c matches abc or adc, but not a2c.

TestComplete uses the regular expression syntax adopted for JavaScript regular expressions. Use this syntax regardless of the script language your TestComplete uses. For complete information on the supported tokens, see –

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

If a step description contains parameter placeholders (like {arg}), TestComplete doesn’t apply regular expressions to the description.

{arg} parameters

• If you change a step description in a BDD scenario, then, most likely, you will have to change the binding expression in your script code. Though you can use regular expressions to make binding expressions more prone to changes, we recommend that you check the binding settings whenever you change test step descriptions in the Gherkin editor.

• Note that literals in linking expressions are case-sensitive, so you need to update the expressions even if you just replaced upper-case letters with lower-case letters in step descriptions.