When using a UI Component based form and adding a custom regular expression pattern validation to an input field, the supplied pattern is not properly converted from a string to a javascript RegEx object.
validation item to an input fieldSpecify a pattern validation rule with a custom regular expression pattern. E.g.
<item name="validation" xsi:type="array">
<item name="required-entry" xsi:type="boolean">true</item>
<item name="no-whitespace" xsi:type="boolean">true</item>
<item name="pattern" xsi:type="string">^[a-zA-Z][a-zA-Z0-9_.-]{3,}$</item>
</item>
pattern value should be interpreted as a RegEx object OR sent through new RegEx within the javascript.param.test is not a function.

@bap14 thank you for your report.
Given this issue is reported against Enterprise edition, please report via the Support portal of your account or Partner portal if you are a partner reporting on behalf of a merchant. Github is intended for Community edition reports given no account management for CE users. This will allow for proper tracking of issues at the account level.
@veloraven I installed Magento CE 2.1.7 and added my custom module and confirmed this does occur in the CE release as well. I would prefer to keep this in the public domain in case there are other developers running into this same issue. I can report it in both if necessary. I'll update the initial posting to include the CE edition as well.
I didn't specify this earlier, but I was working in the admin area, not the frontend.
Magento CE 2.1.7, Frontend Shippment Address in Checkout, added pattern validation by LayoutProcessorPlugin:
... ['shipping-address-fieldset']['children']['street']['children'][0]['validation']['pattern'] = "/.*[0-9].*/";
Same problem: is passed as string to pattern validation in rules.js
@bap14 If this issue is actual for Enterprise Edition only, please address it to Magento Support.
As specified a few comments back @Stas94 the issue occurs in both CE and EE.
@bap14, thank you for your report.
We've created internal ticket(s) MAGETWO-80609 to track progress on the issue.
Internal ticket to track issue progress: MAGETWO-82426
The issue has been fixed and delivered to 2.2-develop branch. Will be available with 2.2.2 release
Hi @bap14. Thank you for your report.
The issue has been fixed in magento-engcom/magento2ce#1284 by @magento-engcom-team in 2.3-develop branch
Related commit(s):
The fix will be available with the upcoming patch release.
Hi @bap14. Thank you for your report.
The issue has been fixed in magento/magento2#17213 by @mageprince in 2.1-develop branch
Related commit(s):
The fix will be available with the upcoming 2.1.15 release.
Most helpful comment
@veloraven I installed Magento CE 2.1.7 and added my custom module and confirmed this does occur in the CE release as well. I would prefer to keep this in the public domain in case there are other developers running into this same issue. I can report it in both if necessary. I'll update the initial posting to include the CE edition as well.