Tests are state-full and chaotic

[albenik]

Description

• Multiple tests reads and overwrites single file without
• Multiple tests reads and overwrites file Book1.xlsx under version control:
  • It makes VCS tree dirty after test.
  • Every second run operates test data not equals to first run (on clean VCS tree state).
  • File with test data can be occasionally commited and possible break future tests.
• Multiple unrelated check placed in single unit test run without any isolation.

Steps to reproduce the issue:

1. Checkout master
2. Rut tests go test ./...
3. Check file tree state git state

Describe the results you received:

Same VCS file tree state after every test run.

Describe the results you expected:

Dirty VCS file tree state after test run.

Output of go version:

go version go1.11.4 darwin/amd64

Excelize version or commit ID:

9a6f66a996eb83f16da13416c5fca361afe575b0

Environment details (OS, Microsoft Excel™ version, physical, etc.):

MacOS Mojave

[albenik]

It will be better to discuss relative to real code, so I made PR.