Table of Contents

Functions

TeaPie provides a lightweight function system for generating dynamic values in scripts and .http files.

Function Naming Rules

  • Must start with $
  • Allowed characters: letters, digits, _, ., $, -
  • Pattern used by parser: ^\$[a-zA-Z0-9_.$-]*$
  • Function names are case-sensitive.
  • Function notation in .http files follows: {{(\$.*)}}

Function Levels

TeaPie supports two levels of functions, determining visibility and resolution order:

Level Scope & Behavior
Default Built-in functions available to all test cases and collections.
Custom User-registered functions that live for the current collection run.

Function Resolution Order

Functions are resolved in this order:

  1. Default Functions
  2. Custom Functions

The first match is executed.

Using Functions in HTTP Files

Syntax (no parentheses, no commas; max 2 arguments):

  • {{$functionName}}
  • {{$functionName arg1}}
  • {{$functionName arg1 arg2}}

Notes:

  • Arguments are whitespace-separated tokens (maximum two per function).
  • Use quotes for values with spaces: {{$now "yyyy-MM-dd HH:mm"}}
  • Both single and double quotes are supported.
  • Function names are case-sensitive.
  • Internally, arguments are tokenized using a command-line parser and converted to the target parameter types.

Using together with Variables:

  • You can pass Variables as function arguments by embedding variable notation inside the function call.
  • Variable notation must follow variable rules (name pattern, {{variableName}}).
  • Examples:
    • {{$add {{MyNumber}} 2}} // passes variable MyNumber as first argument
    • {{$upper "{{FullName}}"}} // if the variable value may contain spaces, wrap it in quotes
  • You can also mix standalone variables and functions in the same line, e.g.:
    • X-Trace-Id: {{RequestId}}-{{$guid}}
    • X-Date: {{$now "yyyyMMdd"}}-{{EnvironmentName}}

If a function is not found, TeaPie throws an error during resolution.

Built-in Functions

The following functions are available by default:

Name Signature Description Example
$guid Guid $guid() Generates a new GUID. {{$guid}}
$now string $now(string? format) Current local time formatted via DateTime.ToString(format). If format is omitted, default formatting is used. {{$now "yyyy-MM-dd"}}
$rand double $rand() Random double in the range [0, 1). {{$rand}}
$randomInt int $randomInt(int min, int max) Random integer in the range [min, max). {{$randomInt 1 100}}

Notes:

  • $now uses DateTime.Now and the same formatting behavior as DateTime.ToString(string?).

Example:

# Generate values with functions
POST https://example.com/api/items
Content-Type: application/json

{
  "id": "{{$guid}}",
  "createdAt": "{{$now "yyyy-MM-dd'T'HH:mm:ss"}}",
  "score": {{$randomInt 10 20}},
  "ratio": {{$rand}}
}

Working with Functions in C#

Access functions through the TeaPie instance (tp).

2️⃣ Registering via TeaPie

TeaPie supports registering functions with 0–2 parameters (maximum two arguments).

// 0-arg
tp.RegisterFunction("$buildNumber", () => Environment.GetEnvironmentVariable("BUILD_NUMBER") ?? "local");

// 1-arg
tp.RegisterFunction("$upper", (string s) => s.ToUpperInvariant());

// 2-arg (maximum)
tp.RegisterFunction("$add", (int a, int b) => a + b);

1️⃣ Use them in .http files

{{$upper "hello"}}
{{$add 40 2}}

3️⃣ Executing via TeaPie

var id = tp.ExecFunction<Guid>("$guid");
var timeStamp = tp.ExecFunction<string>("$now", "yyyy-MM-dd");
var sum = tp.ExecFunction<int>("$add", 2, 3);

If a function is not found or execution fails, TeaPie throws an error during resolution.

Argument Conversion

  • Arguments from .http files are strings
  • TeaPie converts them to expected parameter types using .NET conversion (Convert.ChangeType(...))
    • Works for common primitives (int, double, bool, DateTime, etc.)
    • Uses the current culture during parsing
  • If conversion fails, execution throws an exception

Tip: Prefer culture-invariant formats in .http files for dates and decimals when needed.

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