Disable all observers in your test suite by default. They should not be complicating your model tests because they should have separate concerns anyway. You don't need to unit test that observers actually fire, because ActiveRecord's test suite does that, and your integration tests will cover it.

Do not test the internal implementation of the child components:

Another common gotcha is that the specs end up verifying the mock is working. If you are using mocks, the mock should support the test, but not be the target of the test.

Don’t test the library

Testing the hasMetricTypes computed prop would seem like a given here. But to test if the computed property is returning the length of metricTypes, is testing the Vue library itself. There is no value in this, besides it adding to the test suite.

The number one problem that I see developers have when practicing test-first development that impedes them from refactoring their code is that they over-specify behavior in their tests. This leads developers to write more tests than are needed, which can become a burden when refactoring code.

Write modules quickly, to meet your needs, with just a few tests for compliance. Avoid extensive specifications.