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This feature is actively being developed and may change before release.
Test Run mode transforms your pipeline into an interactive testing environment where you can push data, observe transformations, and understand exactly what’s happening at every step.

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How It Works

When you start a Test Run:
  1. Source and Sink nodes become stubs — Instead of connecting to real Kafka topics or databases, they become interactive endpoints
  2. The pipeline runs synchronously — Data flows through immediately, making it easy to follow
  3. Every node tracks inputs and outputs — You can inspect what each node received and produced
Test Run Mode Interface

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Starting a Test Run

  1. Click the Test Run button in the toolbar (or use the dropdown next to Play)
  2. The pipeline enters test mode — you’ll see stub indicators on source and sink nodes
  3. Source nodes display an input area where you can push JSON messages

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Pushing Test Data

With Test Run active, each source node shows a JSON input panel: 
{
  "id": 123,
  "customer": {
    "name": "Alice Johnson",
    "email": "alice@example.com"
  },
  "items": [
    {"sku": "WIDGET-01", "price": 29.99, "qty": 2},
    {"sku": "GADGET-05", "price": 49.99, "qty": 1}
  ]
}
Click Send to push the message through the pipeline.

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Inspecting Node I/O

After sending a message, every node displays its input and output data:
NodeInputOutput
Kafka Consumer (stub)—Your test JSON
TransformRaw orderTransformed record
BranchTransformed recordRouted to matching output
JDBC Sink (stub)Final record—
Click on any node to expand its I/O panel and see the full JSON payload. This is invaluable for debugging complex transformations.

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Sink Stub Behavior

Sink nodes in Test Run mode:
  • Display all records they would have written
  • Show the exact payload that would go to Kafka, databases, or external systems
  • Allow you to verify output format before connecting to real systems

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Benefits

No External Dependencies

Test without Kafka, databases, or other systems running

Instant Feedback

See results immediately as data flows synchronously

Full Visibility

Inspect every transformation step with detailed I/O logs

Safe Iteration

Experiment freely without affecting real data

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Best Practices

Use Test Run mode to interactively build and debug your transformations. Once you’re confident in the logic, codify the scenarios as Pipeline Tests for CI/CD.
Try various inputs including:
  • Empty arrays and null values
  • Missing optional fields
  • Boundary conditions (e.g., exactly at threshold values)
  • Invalid data that should be rejected
For pipelines with Branch nodes, test messages that should route to each output to ensure your conditions work as expected.

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Next Steps

Pipeline Tests

Automate testing with YAML test definitions

Deploy Pipelines

Deploy your tested pipeline to production