CAS-System

CAS-System (Constraint Assertion System) lets you express validation logic with declarative syntax, replacing traditional imperative assertion code.

Basic Syntax

&constraintName                    # No parameter
&constraintName(parameter)         # Single parameter
&constraintName(param1, param2)    # Multiple parameters
&constraint1 &constraint2          # Multiple constraints (AND)

Usage Positions

DataTable Format

Then response, with table:
  | id     | name             | age             |
  | &isNum | &contains("Wang") | &between(18,65) |

DocString JSON Format

Then response, with JSON:
  """json
  {
    "id": &isNum &gt(0),
    "name": &isStr &contains(Wang)
  }
  """

Note: Symbol system expressions must NOT be placed inside JSON string quotes "", otherwise they are treated as plain strings.

Constraint List

Type Checks

Constraint	Meaning
`&isNum`	Is numeric
`&isStr`	Is string
`&isBool`	Is boolean
`&isNull`	Is null
`&isNotNull`	Is not null

Numeric Comparisons

Constraint	Meaning	Example
`&eq(value)`	Equals	`&eq(100)`
`&ne(value)`	Not equals	`&ne(0)`
`&gt(value)`	Greater than	`&gt(0)`
`&lt(value)`	Less than	`&lt(100)`
`&ge(value)`	Greater than or equal	`&ge(18)`
`&le(value)`	Less than or equal	`&le(65)`

String Operations

Constraint	Example
`&contains(substring)`	`&contains("Wang")`
`&startsWith(prefix)`	`&startsWith("Mr.")`
`&endsWith(suffix)`	`&endsWith(".com")`
`&matches(regex)`	`&matches("\\d{4}-\\d{2}-\\d{2}")`
`&length(min,max)`	`&length(2,10)`

Array Operations

Constraint	Example
`&hasItem(item)`	`&hasItem("admin")`
`&hasNoItem(item)`	`&hasNoItem("guest")`
`&size(count)`	`&size(5)`
`&isEmpty`	`&isEmpty`
`&isNotEmpty`	`&isNotEmpty`

Existence Checks

Constraint	Example
`&hasField(fieldName)`	`&hasField("createdAt")`
`&noField(fieldName)`	`&noField("password")`

Range Checks

Constraint	Example
`&between(min,max)`	`&between(18,65)`
`&notBetween(min,max)`	`&notBetween(0,17)`
`&oneOf(val1,val2,...)`	`&oneOf("admin","user")`
`&noneOf(val1,val2,...)`	`&noneOf("banned")`

Constraint	Example
`&sameTime(datetime)`	`&sameTime("2025-11-04T08:00:00")`
`&before(datetime)`	`&before("2025-12-31")`
`&after(datetime)`	`&after("2025-01-01")`
`&sameDay(date)`	`&sameDay("2025-11-04")`
`&timeRange(start,end)`	`&timeRange("09:00","17:00")`
`&withinDays(days)`	`&withinDays(7)`

Time constraint parameters support the now keyword and relative time syntax, which resolve to the MockTime set by TimeControl.

Supported relative time units:

Unit	Symbol	Example
Seconds	`s` (lowercase)	`now-30s`
Minutes	`m` (lowercase)	`now+5m`
Hours	`h` (lowercase)	`now-2h`
Days	`d` (lowercase)	`now+7d`
Months	`M` (uppercase)	`now-1M`

| createdAt      | expiresAt      | updatedAt        |
| &sameTime("now") | &after("now+7d") | &before("now-30m") |

Multiple Constraint Combination

Multiple constraints separated by spaces form an AND relationship:

| field | &isNum &gt(0) &lt(100) &ne(50) |
# Must simultaneously: be numeric, greater than 0, less than 100, not equal to 50

With Variables

CAS parameters can reference variables:

| &eq($expectedValue)    |  # Use variable as comparison value
| &gt($minThreshold)     |  # Dynamic lower bound
| &between($min, $max)   |  # Dynamic range

Usage Restrictions

CAS cannot be mixed with >contextKey in the same column:

# ❌ Wrong: same column has both extraction (>) and validation (&)
| >recordId |
| &isNum    |

# ✅ Correct: use separately
When punch, call table:
  | >recordId |
  | <id       |

Then response, with table:
  | recordId              |
  | &eq($recordId) &isNum |

Complete Example

Feature: Order Validation

  Example: Validate order response
    When (UID="$Alice.id") create order, call table:
      | >order1.id | productId | quantity |
      | <orderId   | 123       | 2        |
    Then create order(201) response, with table:
      | orderId       | status                     | amount     | createdAt                        |
      | &isNum &gt(0) | &oneOf("pending","active") | &ge(1000)  | &sameTime("2026-01-27T10:00:00") |

CAS-System

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