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

# Testing rules

> Validate transaction monitoring rules against historical data before activation using batch testing and single-transaction evaluation.

Testing lets you validate a rule against real historical transactions before activating it. This helps you understand how many alerts the rule would generate, identify false positives, and fine-tune conditions before going live.

The Rule Builder includes a dedicated **Test** step (step 3 of the wizard) with two testing modes: batch testing and single-transaction evaluation.

***

## Batch testing

Batch testing evaluates your rule against a sample of historical transactions to measure its impact at scale.

### Running a batch test

1. Open the **Test** step in the Rule Builder.
2. Select a **time range** — choose a preset period (last 7 days, last 30 days, etc.) or set a **custom date range**.
3. Set the **sample size** — up to 1,000 transactions.
4. Click **Run Test**.

Corsa pulls matching transactions from the selected period, evaluates each one against your rule's current conditions, and displays the results.

### Understanding batch results

After the test completes, you see:

| Metric                   | Description                                                    |
| ------------------------ | -------------------------------------------------------------- |
| **Matched transactions** | How many transactions triggered the rule.                      |
| **Alert ratio**          | Percentage of sampled transactions that would generate alerts. |
| **Condition paths**      | Breakdown by which condition group (path) was triggered.       |

The results table lists every sampled transaction with its evaluation outcome. Click any row to see which specific conditions matched or failed.

### Managing test tabs

You can run multiple tests with different configurations and compare results:

* Each test runs in its own **tab**.
* Rename tabs to track what you changed between tests (e.g., "Threshold 50k" vs. "Threshold 100k").
* Delete tabs you no longer need.

***

## Single-transaction testing

Single-transaction mode evaluates your rule against one specific transaction, showing a detailed per-condition breakdown.

### Running a single-transaction test

1. In the **Test** step, switch to **Single transaction** mode.
2. Enter the **transaction ID**.
3. Click **Run**.

### Understanding single-transaction results

The results show each condition in your rule with its pass/fail status:

| Column        | Description                                       |
| ------------- | ------------------------------------------------- |
| **Condition** | The property and operator being checked.          |
| **Expected**  | The value your condition requires.                |
| **Actual**    | The value found on the transaction.               |
| **Result**    | Whether this specific condition passed or failed. |

This view is useful for debugging why a rule did or did not fire on a particular transaction.

<Tip>You can click **Switch to batch test** to go back to batch mode, or re-run the single-transaction test after adjusting conditions.</Tip>

***

## Formula drift warning

If you modify conditions after running a test, the Rule Builder shows a warning indicating that the test results may no longer reflect the current rule definition. Re-run the test to get accurate results for your updated conditions.

***

## Best practices

* **Test before activating.** Run a batch test over at least 7 days of data to gauge alert volume.
* **Watch the alert ratio.** A very high ratio (e.g., over 20%) may indicate the rule is too broad and will overwhelm your team with alerts. Consider tightening conditions or raising thresholds.
* **Use single-transaction mode for debugging.** If a rule unexpectedly matches or misses a transaction, single-transaction testing shows exactly which conditions passed or failed.
* **Compare variations.** Use multiple test tabs to compare different threshold values or condition combinations side by side.

***

## What's next?

<CardGroup cols={2}>
  <Card title="Building rules" icon="pen-ruler" href="/transaction-monitoring/building-rules">
    Return to the Rule Builder walkthrough to finalize and activate your rule.
  </Card>

  <Card title="Conditions reference" icon="code" href="/transaction-monitoring/conditions-reference">
    Adjust conditions using the full operator and aggregation reference.
  </Card>
</CardGroup>