FindReplace unit tests

https://trello.com/c/qvHL6r4i/45-unit-tests-for-existing-find-replace-find-in-files-features

- [x] Create a New FindReplace-test.js for all tests
  already existed

- [ ] Add Find First, Find Next, Find Prev, Find Last helper function 


- [ ] Add a Replace helper function 


- [ ] Add Search result verification helper 


- [ ] Add a Replace result verification helper 


- [ ] Add some test files for both find in document and find in files Tests


- - - - -

- [x] Invoke Find with selection (make sure search text is selection)
  added: "should get single selection as initial query"


- [x] Invoke Find without selection (make sure search text is empty)
  added: "should use empty initial query for single cursor selection", and
         "should use empty initial query for multiple cursor selection"

- [x] Invoke Find next while Find is open with no text
  existing: "should no-op on Find Next with blank search"

- [ ] Invoke Find to ensure all tickmarks are present and results are highlighted


- [ ] Invoke Find with Case sensitive to ensure that all case sensitive matches are found


- [ ] Invoke Find without Case sensitive to ensure that all matches are found


- [ ] Invoke Find with Regex to ensure that regex is found


- [ ] Change one of the find hits to ensure results panel is updated Replace


- - - - -

Find in Files - Same tests as Find?

- - - - -

- [ ] Invoke replace with a selection (make sure search text is selection)


- [ ] Invoke replace without a selection (make sure search text is empty)


- [ ] Inoke replace with plain text


- [ ] Inoke replace with regx capture groups and replace parameter


- [ ] Invoke Replace All with Plain text to ensure all instances are replaced


- [ ] Inoke Replace with RegEx


- [ ] Replace Yes/No/Skip to ensure next instance is found


- [ ] Replace Yes/No/Skip to ensure instance is Replaced or Not