# Testing/Debugging code for Calculate and Custom Logic Block using UI
### **1. Overview**
The **customLogicBlock** and **calculateContainerBlock** can be executed in a “dry-run” mode. This feature provides a sandboxed environment for testing the logic of a block independently, helping policy developers validate their implementation with different input scenarios without affecting the main policy.
### **2. Custom Logic Block**
#### **Dry-Run Execution**
The `customLogicBlock` supports isolated dry-run execution. This means it can be tested independently of other blocks in a policy, allowing for detailed debugging and rapid prototyping.
Execution is controlled through a step-by-step interface in the UI, enabling users to define parameters, input data, and immediately inspect the results.
***
### **3. Dry-Run Execution Steps**
#### **Step 1: Configure Block Properties**
Users can adjust various configuration options related to the block directly within the dry-run interface. This avoids the need to navigate back to the main policy editor and streamlines the testing workflow.
***
#### **Step 2: Provide Input Data**
The block can be tested using mock input data. Three primary input methods are supported:
**a. Schema-Based Input**
* Select a data schema from a dropdown list.
* A dynamic form is generated based on the schema, allowing users to fill in relevant fields.
* Ideal for users who prefer a structured and guided input interface.
**b. JSON Editor**
* Directly input JSON-formatted data using the built-in editor.
* Best suited for advanced users or when precise control over the input format is needed.
**c. File Upload**
* Upload a JSON file containing the test data.
* The file must be well-formed JSON.
> **Note**: Only valid JSON inputs are accepted. Malformed files will cause parsing errors.
***
#### **Step 3: Use Historical Data**
The **History** tab displays saved input/output pairs from previous executions during dry-run mode. This is helpful when working with complex workflows that generate intermediate data.
To utilize this:
1. Enable **Policy Dry-Run Mode**.
2. Execute the policy workflow normally.
3. Once execution reaches the target block, its context (input/output) will be saved and visible in the history tab.
> **Important Notes:**
* Historical data is only available in dry-run mode and is cleared upon exit.
* Code changes made in dry-run are not persisted. To retain them, re-enter the changes in **Draft Mode** of the policy.
***
#### **Step 4: Write and Test Code (customLogicBlock only)**
In the final step:
* Modify the code as needed.
* Press the **Test** button to execute.
**Debugging Tips**
Use the `debug` function to output logs:
```javascript
javascriptCopyEditdebug("Variable Value", variable);
```
* Outputs appear in the **Logs** tab.
* Has no effect (noop) when the policy is in **Published Mode**.
***
### **4. Viewing Test Results**
Upon completion of the dry-run, the results are split into several tabs:
| Tab | Description |
| ---------- | --------------------------------------------------------------- |
| **Input** | Displays the ingress VC (Verifiable Credential) documents used. |
| **Logs** | Shows output from `debug()` and system logs. |
| **Output** | Final result VC document (if execution succeeds). |
| **Errors** | Any errors encountered during test-run. |
***
### **5. calculateContainerBlock**
All features described for `customLogicBlock` apply to `calculateContainerBlock`, **except** it does not include a code editor tab. This block is evaluated based on its configured calculation logic rather than custom scripting.
***
### **6. API Support for Dry-Run**
The following API endpoints are available to programmatically interact with the dry-run feature:
#### **Get Block History**
```http
httpCopyEditGET /api/v1/policies/:policyId/dry-run/block/:tagName/history
Permissions: POLICIES_POLICY_UPDATE
```
* Retrieves the list of historical test data for the specified block.
#### **Execute Block Dry-Run**
```http
httpCopyEditPOST /api/v1/policies/:policyId/dry-run/block
Permissions: POLICIES_POLICY_UPDATE
```
* Submits the block for dry-run execution with the specified input.
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