Variables and expressions

Frontend Robot allows you to use variables which can be reused across your tests. These variables can have a static value or a value that is resolved at runtime using functions or simple expressions. Variables can also be pre-assigned at suite level.

Defining variables in a test

To define a variable in a test, use the Assign Variable instruction. The instruction takes as input the the following:

  • A variable name, which can only contain alphanumeric characters and underscores.
  • An assignment type, which can be one of the following:

    • Assign a value: allows you to assign a static value to the variable
    • Assign from element value: assigns the specified element value to the variable
    • Assign from element text: assigns the specified element text content to the variable
    • Assign from element attribute: assigns the specified attribute value of the specified element to the variable
  • An argument, which can be one of the following, depending on the assignment type selected:

    • The variable static value
    • An element selector
    • An attribute name

Take a look at the following screenshot for an example:

Assigning a variable using a static value
Assigning a variable using a static value

Using a variable

You can use variables in most instruction arguments, including selectors. To do so, simply wrap the variable name within ${ and }. For example a variable named todo can be used with the string ${todo}. The following screenshot shows you how a variable can be included in a Send keys instruction:

Using a variable
Using a variable

And below you can see the results of the instruction:

Result of using a variable
Result of using a variable

Using built-in functions

Sometimes you may want to use some data that is defined at runtime. The most common use case is having a random string or the current date to be inserted into a form. You can achieve this by using a set of built-in functions.

The format of a function is almost the same of that of a variable with the addition of two parenthesis () used to specify a comma-separated list of arguments. For example to generate a random string you can use ${randomString()}. To render the current date in the format 2018-01-30 you can use ${now('YYYY-MM-DD')}. The screenshot below shows you an example:

Using functions
Using functions

And below is the result of the above instruction:

Using functions. Result.
Using functions. Result.

You can find here a reference of all the available functions

Using simple expressions in variables

Frontend Robot allows you to use simple logical expressions inside the variable statement. Supported operators are the logical and &&, or || and the ternary operator <condition> ? <then> : <else>.

TIP: to use a default value in place of a missing variable you can use the expression

${variable || "default value"}

Using variables and functions to define other variables

Sometimes it can be useful to use functions and other variables when defining a variable’s value. For example you can define a variable having value Last todo: ${randomSentence()}.

Let’s show an example in the screenshot below:

Using composite variables
Using composite variables

This is what we did in the screenshot above:

  1. We assigned a variable using the randomSentence() function
  2. We used the newly created variable in a Send keys instruction
  3. We reused the same variable in an Element Exists instruction

Defining variables at suite level

You can also pre-define a set of variables at suite level. This is explained in a separate article.


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