Move unit tests adjacent to the source of the system under testing

[JunTaoLuo]

As part of the effort to improve our unit tests, we've decided to move unit tests to the same directory as the source file of the system under testing.

For example:

src\applications\vaos\components
\- subdirectoryA
  \- SubcomponentA.jsx
   - SubcomponentA.unit.spec.js
 - Component1.jsx
 - Component1.unit.spec

Primarily, this provides the benefit of making it easier to find the associated test file for each component and to identify which source files is missing associated tests.

Note that naming of the unit tests should:

• start with the same file name as the source file, until the file extension
• end with .unit.spec.js as specified here.

Definition of Done

• [ ] All unit existing tests are moved to match the specifications in the description above
• [ ] All unit tests are recognized by the test runner and pass (locally and on CI)
• [ ] Coverage metrics remain constant before and after the change

[JunTaoLuo]

One open question is where should the test utilities (e.g. mocks, helpers) be located? If it is placed in the same directory as the source and unit test files, it becomes a little more difficult to differentiate between source files and test utilities. We need to test this out to ensure the coverage tool recognizes test utilities correctly.

cc @simiadebowale @vbahinwillit

[Bren22va]

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