Some expressions for Calculate rule will silently prevent user from saving the Form

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: Master
• Fix Version/s: 7.1.X, Master
• Component/s: Forms
• Labels:
  • 7.1-should
  • fw_test_unit
  • liferay-fixpack-dxp-1-7110
  • not_reproducible_on_metal
• Fix Priority: 4
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/61212

Steps to Reproduce:

1. Add a new Form
2. Add 4 numeric fields
   • Num1, Num2, Num3, Num4
3. Add a 5th numeric field for "Total"
4. Save form
5. Go to Rules
6. Add a new rule:
   • If Num1 is not empty
   • Calculate (Num1 + Num2 + Num3 + Num4) * 0.25 into "Total"
7. Save Rule
8. Attempt to Save Form

Expected Result:
Form will save or give a helpful error message to the user due to expression being unsupported.

Actual Result:
Form fails to save with generic error message, Rule is lost. No error in the console.

The save failure becomes more likely if the user is using multiple fields (3+) combined with static values in the expression.

Examples of working expressions:

(Num1+Num2+Num3)*Num4
(Num1+Num2)*9.8
(Num1+Num2+Num3)
(Num1+Num2+Num3)+Num3
(Num1-Num2*Num3)+Num3
(2+3+6)-Num1
(Num1 * Num2)
(Num1 * Num2) + Num3
(Num1 + 0.25)
(Num1 + Num2) * Num1

Examples of expressions that cause a silent save failure:

(Num1 + Num2 + Num3 + Num4) * 0.25
(Num1+Num2+Num3)*3
Num1+Num2+Num3*3
(Num1+Num2+Num3)-3
(Num1+Num2+Num3)+3
(Num1-Num2*2)-Num3
(Num1 * Num2) + 0.25
(Num1 * Num2)*0.25