> ## Documentation Index
> Fetch the complete documentation index at: https://docs.semantictest.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Pipelines

> Understanding the pipeline architecture

## What is a Pipeline?

A pipeline is a sequence of **blocks** that execute in order. Each block performs one specific task, and data flows through the pipeline via named **slots**.

```
HttpRequest → JsonParser → Validate → LLMJudge → Assert
```

This architecture makes tests:

* **Readable**: Each block has a clear purpose
* **Reusable**: Mix and match blocks for different scenarios
* **Maintainable**: Easy to add, remove, or reorder steps

## Basic Pipeline Structure

```json theme={null}
{
  "tests": [{
    "id": "my-test",
    "pipeline": [
      {
        "id": "step1",
        "block": "HttpRequest",
        "input": { "url": "https://api.example.com" },
        "output": "response"
      },
      {
        "id": "step2",
        "block": "JsonParser",
        "input": "${response.body}",
        "output": "data"
      }
    ],
    "assertions": {
      "response.status": 200
    }
  }]
}
```

Each block has:

* **id**: Unique identifier for this step
* **block**: The block type to use
* **input**: Data to process (from previous blocks)
* **output**: Where to store the result
* **config** (optional): Block-specific configuration

## Execution Flow

<Steps>
  <Step title="Initialize">
    Pipeline loads and prepares all blocks
  </Step>

  <Step title="Execute in Sequence">
    Each block runs one after another:

    1. Reads inputs from the DataBus
    2. Processes data
    3. Writes outputs to the DataBus
  </Step>

  <Step title="Validate Assertions">
    After all blocks complete, assertions are checked
  </Step>

  <Step title="Report Results">
    Success or failure with detailed information
  </Step>
</Steps>

## Why Pipelines?

### Composability

Build complex tests from simple blocks:

```json theme={null}
{
  "pipeline": [
    { "block": "HttpRequest" },      // Fetch data
    { "block": "JsonParser" },       // Parse response
    { "block": "ValidateContent" },  // Check content
    { "block": "LLMJudge" },         // Semantic validation
    { "block": "ValidateTools" }     // Check tool calls
  ]
}
```

### Reusability

Use the same blocks in different combinations:

```json theme={null}
// Test 1: Simple validation
{
  "pipeline": [
    { "block": "HttpRequest" },
    { "block": "ValidateContent" }
  ]
}

// Test 2: Semantic validation
{
  "pipeline": [
    { "block": "HttpRequest" },
    { "block": "LLMJudge" }
  ]
}
```

### Maintainability

Easy to modify tests:

```json theme={null}
// Add a new step
{
  "pipeline": [
    { "block": "HttpRequest" },
    { "block": "JsonParser" },
    { "block": "ValidateContent" },  // ← New step
    { "block": "LLMJudge" }
  ]
}
```

## Multiple Tests

You can run multiple tests in sequence:

```json theme={null}
{
  "name": "User API Tests",
  "tests": [
    {
      "id": "create-user",
      "pipeline": [ /* ... */ ]
    },
    {
      "id": "get-user",
      "pipeline": [ /* ... */ ]
    },
    {
      "id": "update-user",
      "pipeline": [ /* ... */ ]
    }
  ]
}
```

<Note>
  Each test runs in isolation with its own DataBus. Tests don't share data unless you use `setup`/`teardown`.
</Note>

## Setup and Teardown

For shared setup across tests:

```json theme={null}
{
  "setup": [
    {
      "id": "auth",
      "block": "HttpRequest",
      "input": {
        "url": "https://api.example.com/auth/login",
        "method": "POST",
        "body": { "username": "test", "password": "test123" }
      },
      "output": "authToken"
    }
  ],
  "tests": [
    {
      "id": "test1",
      "pipeline": [
        {
          "block": "HttpRequest",
          "input": {
            "url": "https://api.example.com/users",
            "headers": {
              "Authorization": "Bearer ${authToken.body.token}"
            }
          }
        }
      ]
    }
  ],
  "teardown": [
    {
      "id": "logout",
      "block": "HttpRequest",
      "input": {
        "url": "https://api.example.com/auth/logout",
        "method": "POST"
      }
    }
  ]
}
```

**Setup** runs once before all tests.
**Teardown** runs once after all tests (even if tests fail).

## Next Steps

<CardGroup cols={2}>
  <Card title="Data Flow" icon="diagram-project" href="/concepts/data-flow">
    Learn how data moves through pipelines
  </Card>

  <Card title="Browse Blocks" icon="cube" href="/blocks/overview">
    See all available blocks
  </Card>
</CardGroup>