Reproduction steps:

1. Open "UndoMinimalRepro.zip" project
2. Open Scene "1"
3. Click on "GameObject" in the Hierarchy window
4. In the Inspector window click on "Test (Script)" -> "Method" and set to "Nothing"
5. Increase the number by clicking on the bar with the "0"
6. Enter Play mode
7. Observe the number counter
8. Repeat from step 4 (Only select the next Method) to see the result of other tests

Expected Result: It should be better documented what should happen
Actual Result: It's unclear if this is the expected behavior

Reproduced with: 2017.3.0a1, 2017.2.0b4, 2017.1.0p2, 5.6.2p4, 5.5.4p2