Add unit tests for Meter Reading DocType

[Levinmunyelele]

This PR adds unit tests for the Meter Reading DocType to ensure functionality and data integrity. Covers basic validations and business logic.

[muruthigitau]

Hey @Levinmunyelele,

I had a look at the Meter Reading tests and wanted to share some feedback and suggestions. Overall, things look pretty solid, but there are a few spots where we could tidy up the code and improve readability.

Happy to discuss or help out with any changes whenever you want!

🧩 General Observations

• ✅ Structure: The test suite is generally well-organized. Use of setUpClass for shared test setup is appropriate.
• ✅ Testing Approach: A good balance between unit and integration tests is observed.
• ✅ Documentation: Docstrings are present and helpful, providing clear insight into the test intent.

---

Code Issues and Fixes

1. Syntax Error, Misplaced Logic, serial_no Handling & Missing customer Definition

def create_warranty_claim(...):
    ...
    if not frappe.db.exists("Warranty Claim", ...):
        create_warranty_claim(...)

Issues:

• ❌ Syntax Error: Misplaced logic and conditional calls inside the function leads to infinite recursion and unreachable code.
• ❌ serial_no Handling: None or empty string values aren't handled, which may cause issues with validation or database constraints.
• ❌ Missing customer Definition: The customer variable is referenced but never initialized or passed into the function.

✅ Fixes:

• Move the create_warranty_claim(...) calls outside the function to avoid logical/syntax errors.
• Safely handle serial_no with:

"serial_no": serial_no or ""
# or
if serial_no:
    doc.serial_no = serial_no

• Define a customer before using it:

---

2. Manual Setting of name Field

"name": "WC-001-TEST-MULTIPLE"

Issue:
Manually setting name risks collisions since it's usually system-generated.

✅ Fix:
Avoid this unless:

• You're using set_name=True
• You ensure it's unique

---

3. ⚠️ Use of ignore_links=True

.insert(ignore_permissions=True, ignore_links=True)

Issue:
Suppressing link validation may lead to inconsistent or invalid references in data.

✅ Fix:
Only use this in isolated tests. Prefer:

.insert(ignore_permissions=True)

---

4. Improper Multi-line serial_no Usage

"serial_no": "SN001\nSN002\nSN004"

Issue:
serial_no is likely a single Link field. Multi-line strings won’t work.

✅ Fix:
Use only a single valid serial number per warranty claim.

---

5. ⚠️ Missing Test Cleanup (tearDownClass)

Issue:
Without cleanup, tests leave behind residual data, which may cause interference between test runs.

✅ Fix:
Add cleanup logic

[Levinmunyelele]

Hi @muruthigitau, I've implemented all your feedback:

• Fixed serial_no handling and company field
• Removed multi-line serials
• Added tearDownClass cleanup
• Moved test_meter_reading.py back to the correct path

Kindly review when you get a chance. Thank you

[muruthigitau]

NOTE: 'crm' should not be removed from required_apps as it is used in the app

[Levinmunyelele]

All updates done. Let me know if any further changes are needed. Thanks again.