feat: Add test for cache clean

Author: howjmay

Diff for: test/test_cache.py

@@ -0,0 +1,41 @@
+# This file is part of arduino-cli.
+#
+# Copyright 2020 ARDUINO SA (http://www.arduino.cc/)
+#
+# This software is released under the GNU General Public License version 3,
+# which covers the main part of arduino-cli.
+# The terms of this license can be found at:
+# https://www.gnu.org/licenses/gpl-3.0.en.html
+#
+# You can be released from the requirements of the above licenses by purchasing
+# a commercial license. Buying such a license is mandatory if you want to modify or
+# otherwise use the software for commercial activities involving the Arduino
+# software without disclosing the source code of your own applications. To purchase
+# a commercial license, send an email to [email protected].
+import os
+import platform
+
+
+def test_cache_clean(run_command):
+    """
+    Clean the cache under arduino caching file directory which is
+    "<Arduino configure file path>/staging"
+    """
+    result = run_command("cache clean")
+    assert result.ok
+
+    # Generate /staging directory
+    result = run_command("lib list")
+    assert result.ok
+
+    result = run_command("cache clean")
+    assert result.ok
+
+    running_platform = platform.system()
+    homeDir = expanduser("~")
+    if running_platform == "Linux":
+        assert not (os.path.isdir(homeDir + ".arduino15/staging"))
+    elif running_platform == "Darwin":
+        assert not (os.path.isdir(homeDir + "Library/Arduino15/staging"))
+    elif running_platform == "Windows":
+        assert not (os.path.isdir(homeDir + "Arduino15/staging"))