Expressions and variables

AutoTestX has a small, strict expression language. You use it in two ways.

Field kind	Example field	How it reads
Template	Type → value, Open → url, Text → expected, HTTP → url/headers/body	Literal text. Only the parts inside {{ }} are expressions. Order {{poNumber}} for {{vendor}}
Expression	If → condition, While → condition, Expression → expression, Set variable → value, For each → items, Poll → until	The whole field is one expression. status == 'Approved' AND total > 0

The editor shows which kind a field is under the field.

In an expression field you may also write variables with braces: {{status}} == 'Approved' means the same as status == 'Approved'.

Variables and where they come from

{{name}} is looked up in this order. The first match wins:

Order	Source	Set by
1	Loop variables	For each … as line → {{line.item}}; Repeat … as i; component parameters
2	Runtime variables	Steps during the run: Extract, Set variable, HTTP saveAs, Custom code assignTo
3	Test variables	Test settings → Test variables (JSON)
4	Environment variables	The environment’s Variables (JSON)

Two reserved prefixes are looked up first and never collide with variables:

Prefix	Meaning
{{secret.NAME}}	A secret from the run’s environment. Masked everywhere.
{{data.column}}	The current row in a data-driven run. Reserved only when the test has a data source.

Paths

Use dots for object fields and list positions: {{order.body.id}}, {{orders.body.0.id}}, {{line.item}}. Brackets work too: orders.body[0].

A missing variable is an error

{{custmer}} (a typo), or a variable whose setting step did not run, fails the step with Unresolved reference “custmer”. Check the variable name and that an earlier step assigned it. It never becomes an empty string. Silently typing nothing is how tests pass while testing nothing.

Values and types

Type	Literals
text	'single' or "double" quotes, with \n, \t, \' escapes
number	42, 3.14
boolean	true, false
null	null
list	[1, 2, 3], ['a', 'b']

A template that is exactly one placeholder ({{qty}}) keeps the value’s type, e.g. a number. Mixed text (Qty: {{qty}}) is always text.

Strict typing

There is no automatic type conversion:

• "5" == 5 is an error (Cannot compare string with number. Convert explicitly, for example NUMBER(value).), not false.
• + is arithmetic only. 1 + "1" is an error. Join text with CONCAT().
• Only true and false are truthy. count AND … is an error; write count > 0 AND ….

Values read from the page (Extract) are text. Convert with NUMBER() before numeric comparisons.

Operators

From lowest to highest precedence:

Operator	Meaning
OR, ||	Logical or (short-circuit)
AND, &&	Logical and (short-circuit)
NOT, !	Logical not
==, !=	Strict equality (lists compare item by item)
<, <=, >, >=	Two numbers or two texts
+, -	Numbers only
*, /, %	Numbers only. Dividing by zero is an error.
-x	Negation
( )	Grouping

AND, OR, NOT are case-insensitive.

Functions

Function names are case-insensitive. Functions cannot reach the page, network, files or secret store. For that, use a step.

Text

Function	Result	Example
UPPER(t) / LOWER(t) / TRIM(t)	Converted text	UPPER('po') → 'PO'
LENGTH(t or list)	Number of characters or items	LENGTH('PO-1') → 4
SUBSTRING(t, start[, length])	Part of the text (0-based)	SUBSTRING('PO-1234', 3) → '1234'
REPLACE(t, find, with)	Every occurrence replaced	REPLACE('a-b-c', '-', '/') → 'a/b/c'
CONCAT(a, b, …)	Joined text	CONCAT('Vendor ', NOW())
SPLIT(t, separator)	List	SPLIT('a,b', ',') → ['a','b']
JOIN(list, separator)	Text	JOIN(['a','b'], ', ') → 'a, b'
CONTAINS(t or list, x)	true/false	CONTAINS(status, 'Approv')
STARTS_WITH(t, prefix) / ENDS_WITH(t, suffix)	true/false	STARTS_WITH(poNumber, 'PO-')
PAD_START(t, length[, fill])	Padded text (default fill: space)	PAD_START('42', 5, '0') → '00042'
REGEX_MATCH(t, pattern)	true/false	REGEX_MATCH(poNumber, '^PO-\\d+$')
REGEX_EXTRACT(t, pattern[, group])	Matched text or null	REGEX_EXTRACT('Order PO-77 saved', 'PO-(\\d+)', 1) → '77'

Backslashes in expression text. Inside quotes in an expression, \ starts an escape. The only valid escapes are \n (newline), \t (tab), \\ (a backslash), \' and \". A regex therefore needs doubled backslashes: type '^PO-\\d+$'. Any other escape, such as a single \d, is a syntax error that gives its position and suggests \\d. You see it when you save the step. It is never quietly changed into a different pattern. Character classes avoid the issue: '^PO-[0-9]+$'.

This applies only to expressions. In a template field, such as Text → expected with match regex, type the pattern normally: ^PO-\d+$.

Numbers

Function	Result
NUMBER(x)	Text → number (error if not a number)
ROUND(n[, decimals])	Rounded number
ABS(n)	Absolute value
MIN(a, b, …) / MAX(a, b, …)	Smallest / largest

Lists

Function	Result
COUNT(list)	Number of items
FIRST(list) / LAST(list)	First / last item, or null if empty

Dates

Dates are ISO-8601 text in UTC, e.g. 2026-09-30T21:59:31.000Z.

Function	Result
NOW()	The current date and time
DATE_ADD(date, amount, unit)	Date moved by amount ms, seconds, minutes, hours, days or weeks (negative to go back)
FORMAT_DATE(date, pattern)	Text using yyyy, MM, dd, HH, mm, ss (UTC)

FORMAT_DATE(DATE_ADD(NOW(), 7, 'days'), 'dd/MM/yyyy')   → '07/10/2026'

Examples

Goal	Field	Write
Unique name per run	Set variable → value	CONCAT('Vendor ', NOW())
Check a generated number	Expression	STARTS_WITH(poNumber, 'PO-') AND LENGTH(poNumber) > 3
Compare an extracted amount	Expression	NUMBER(total) == 49.5
Branch on API status	If → condition	response.status == 404
Loop over test data	For each → items	lines
Date in a field	Type → value	{{FORMAT_DATE(NOW(), 'yyyy-MM-dd')}}
Poll until done	Poll → until	response.body.state == 'done'