9a0b7d0450
During the test files may be lost in the temporary directory. Therefore, it would be nice if we reduce dependence of temporary directory. This patch replace buildin method file.write by mock in ShellCacheSchemaTest. Also we need to replace method os.path.exists by mock to correct all checks. Fixes bug: #1267515 Change-Id: I3faca27348e15b28619e49f11d0d6cff5a9e2906