/testfor command detect playes in gamemode 3 [Espectator]

What I expected to happen was...:
The testfor comand had not to detect me on gamemode 3.

What actually happened was...:
The testfor command detected me on gamemode 3.

Steps to Reproduce:
1. Put a command block with "testfor @e[r=5]" command or similar
2. Set gamemode 3 [Espectator]
3. Activate the command block