---
title: "How do I test my custom RegEx before deployment?"
url: "https://dm0bkdes5q7a2ls.productfruits.help/en/article/0d9ba061-4abe-4578-a1e9-15e771ad805d"
language: "en"
last_updated: "2026-05-07T13:53:58.769Z"
---

# How do I test my custom RegEx before deployment?

Testing your custom regex before a full-scale deployment is a critical "Best Practice" to prevent "result floods" (too many false positives) or "silent failures" (missing real data).

Here are the 2 ways to test your RegEx, ranging from a quick syntax check to a real-world environment test.

### The "Single-File" Agent Test (Highly Recommended)

This is the most accurate test because it uses the actual Spirion Search Engine on a real machine.

-   **Step A:** Create a "Golden Set" test file (a Word or Excel doc) containing:
-   -   Valid MRNs in various formats.
    -   MRNs buried in paragraphs of text.
    -   "Near-miss" data (numbers that are almost MRNs but shouldn't match).
-   **Step B:** Place this file in a specific folder on a test endpoint (e.g., `C:\Spirion_Test\`).
-   **Step C:** Create a **Test Policy** in the console:
-   -   **Data Types:** Select *only* your new Custom Regex.
    -   **Locations:** Target *only* that specific folder (`C:\Spirion_Test\`).
-   **Step D:** Run the scan and review the **Match Evidence**. This confirms the agent can read the pattern within the file structure.

### Use External Regex Testers (For Syntax Only)

If you are struggling with the regex logic itself, use a tool like [**Regex101.com**](http://regex101.com/).

-   **Configuration:** Set the flavor to **PCRE** or **Python** (which most closely match Spirion's engine).
-   **The Test:** Use the "Unit Test" feature to ensure your boundaries (`\b`) and quantifiers (`{8}`) are working as expected.
-   **Warning:** External tools only test the *pattern*. They cannot test Spirion-specific features like **Keyword Proximity** or **File Type Decoders**. Always follow up with a "Single-File" test (Method 2).

* * *

### Troubleshooting Checklist

-   **Check your Boundaries:** If your regex is matching parts of longer numbers, ensure you have `\b` at the start and end (e.g., `\b\d{8}\b`).
-   **Check for Case Sensitivity:** If your MRN has letters (e.g., `MRN-123`), ensure your regex accounts for case (e.g., `[Aa][Bb]-\d{5}`) or that the "Case Insensitive" box is checked in the console.
-   **Test Different File Types:** A regex that works in a `.txt` file might behave differently in a complex `.pdf` or `.xlsx` due to how the agent extracts text. Include multiple file formats in your "Golden Set."
-   **Verify Keyword Proximity:** If you added keywords (like "Patient ID"), make sure your test file actually includes those words within the character distance you specified (usually 50-100 characters).

**Summary:** Start with the **Single-File Agent Test** using a "Golden Set" of data to verify real-world performance before enabling the policy for the whole company.