[2/2] #35 Fix infinite plan on user metadata

[sergiught]

Description

Fixes: #35

From: https://auth0.com/docs/api/management/v2#!/Users/patch_users_by_id

The metadata fields are an exception to this rule (user_metadata and app_metadata). These properties are merged instead of being replaced but be careful, the merge only occurs on the first level.

The API behaves in an unexpected way for the user_metadata and app_metadata where the values get merged instead of replaced but only on the first level. This means that if we want to completely remove a key from the object we need to send the key with a null value. We try to work around this and give a more predictable behavior for our terraform users by checking if the value was removed and if so, sending it as null so it also gets removed in the API call.

Checklist

Note: Checklist required to be completed before a PR is considered to be reviewable.

Auth0 Code of Conduct

• I have read and agreed to the terms within the Auth0 Code of Conduct

Auth0 General Contribution Guidelines

• I have read the Auth0 General Contribution Guidelines

Changes include test coverage?

• Yes
• Not needed

Does the description provide the correct amount of context?

• Yes, the description provides enough context for the reviewer to understand what these changes accomplish

Have you updated the documentation?

• Yes, I've updated the appropriate docs
• Not needed

Is this code ready for production?

• Yes, all code changes are intentional and no debugging calls are left over

[sergiught]

We're applying the following explained logic in alexkappa/terraform-provider-auth0#392 (comment), where in order to properly remove something we need to send it's value as null.

This is because the metadata fields are merged instead of being replaced but the merge only occurs on the first level during a PATCH.

[codecov-commenter]

Codecov Report

Merging #250 (ab53fbc) into patch/fix-issue33-user_metadata (82d87a1) will decrease coverage by 0.02%.
The diff coverage is 78.57%.

@@                         Coverage Diff                         @@
##           patch/fix-issue33-user_metadata     #250      +/-   ##
===================================================================
- Coverage                            83.51%   83.48%   -0.03%     
===================================================================
  Files                                   36       36              
  Lines                                 6835     6859      +24     
===================================================================
+ Hits                                  5708     5726      +18     
- Misses                                 898      902       +4     
- Partials                               229      231       +2     

Impacted Files	Coverage Δ
auth0/resource_auth0_user.go	73.75% <78.57%> (+0.13%)	⬆️

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[sergiught]

We're removing this as we added it as a last test case for the TestAccUser scenario.