diff --git a/client/site_tests/platform_CrosDisksDBus/platform_CrosDisksDBus.py b/client/site_tests/platform_CrosDisksDBus/platform_CrosDisksDBus.py
index ba9699d..b23085b 100644
--- a/client/site_tests/platform_CrosDisksDBus/platform_CrosDisksDBus.py
+++ b/client/site_tests/platform_CrosDisksDBus/platform_CrosDisksDBus.py
@@ -10,12 +10,117 @@
 class platform_CrosDisksDBus(test.test):
     version = 1
 
+    def validate_disk_properties(self, disk):
+        # Disk properties provided by the API
+        disk_properties = (
+            ('DeviceFile', dbus.String),
+            ('DeviceIsDrive', dbus.Boolean),
+            ('DeviceIsMediaAvailable', dbus.Boolean),
+            ('DeviceIsMounted', dbus.Boolean),
+            ('DeviceIsOpticalDisc', dbus.Boolean),
+            ('DeviceIsReadOnly', dbus.Boolean),
+            ('DeviceMountPaths', dbus.Array),
+            ('DevicePresentationHide', dbus.Boolean),
+            ('DeviceSize', dbus.UInt64),
+            ('DriveIsRotational', dbus.Boolean),
+            ('DriveModel', dbus.String),
+            ('IdLabel', dbus.String),
+            ('NativePath', dbus.String),
+        )
+
+        for (prop_name, prop_value_type) in disk_properties:
+            # Check if all disk properties are set.
+            if prop_name not in disk:
+                raise error.TestFail("disk.%s not found" % prop_name)
+
+            # Check if each disk property has the right data type.
+            prop_value = disk[prop_name]
+            if not isinstance(prop_value, prop_value_type):
+                raise error.TestFail(
+                        "disk.%s is %s, but %s expected"
+                        % (prop_name, type(prop_value), prop_value_type))
+
+        # Check if DeviceFile has a proper value.
+        if not disk['DeviceFile']:
+            raise error.TestFail(
+                    "disk.DeviceFile should not be empty")
+
+        # Check if the values of DeviceIsMounted and DeviceMountPaths
+        # are consistent.
+        mount_paths = disk['DeviceMountPaths']
+        if disk['DeviceIsMounted']:
+            if len(mount_paths) == 0:
+                raise error.TestFail(
+                        "disk.DeviceMountPaths should not be empty "
+                        "if disk.DeviceIsMounted is true")
+        else:
+            if len(mount_paths) != 0:
+                raise error.TestFail(
+                        "disk.DeviceMountPaths should be empty "
+                        "if disk.DeviceIsMounted is false")
+
+        if mount_paths.signature != dbus.Signature('s'):
+            raise error.TestFail(
+                    "disk.DeviceMountPaths should contain only strings")
+
+        for mount_path in mount_paths:
+            if not mount_path:
+                raise error.TestFail(
+                        "disk.DeviceMountPaths should not contain any "
+                        "empty string")
+
+    def test_is_alive(self):
+        # Check if CrosDisks server is alive.
+        is_alive = self.cros_disks.IsAlive()
+        if not is_alive:
+            raise error.TestFail("Unable to talk to the disk daemon")
+
+    def test_enumerate_device_files(self):
+        # Check if EnumerateDeviceFiles method returns a list of devices.
+        devices = self.cros_disks.EnumerateDeviceFiles()
+        for device in devices:
+            if not device or not isinstance(device, dbus.String):
+                raise error.TestFail(
+                        "device returned by EnumerateDeviceFiles "
+                        "should be a non-empty string")
+
+    def test_get_device_properties(self):
+        # Check if GetDeviceProperties method returns valid properties.
+        devices = self.cros_disks.EnumerateDeviceFiles()
+        for device in devices:
+            properties = self.cros_disks.GetDeviceProperties(device)
+            self.validate_disk_properties(properties)
+
+    def test_get_device_properties_of_nonexistent_device(self):
+        try:
+            properties = self.cros_disks.GetDeviceProperties('/nonexistent')
+        except dbus.DBusException:
+            return
+        raise error.TestFail(
+            "GetDeviceProperties of a nonexistent device should fail")
+
+    def test_mount_nonexistent_device(self):
+        try:
+            path = self.cros_disks.FilesystemMount('/nonexistent', '', [])
+        except dbus.DBusException:
+            return
+        raise error.TestFail("Mounting a nonexistent device should fail")
+
+    def test_unmount_nonexistent_device(self):
+        try:
+            self.cros_disks.FilesystemUnmount('/nonexistent', [])
+        except dbus.DBusException:
+            return
+        raise error.TestFail("Unmounting a nonexistent device should fail")
+
     def run_once(self):
-        # TODO(rtc): Excercise the whole API.
         bus = dbus.SystemBus()
         proxy = bus.get_object('org.chromium.CrosDisks',
                                '/org/chromium/CrosDisks')
-        cros_disks = dbus.Interface(proxy, 'org.chromium.CrosDisks')
-        is_alive = cros_disks.IsAlive()
-        if not is_alive:
-            raise error.TestFail("Unable to talk to the disk daemon")
+        self.cros_disks = dbus.Interface(proxy, 'org.chromium.CrosDisks')
+        self.test_is_alive()
+        self.test_enumerate_device_files()
+        self.test_get_device_properties()
+        self.test_get_device_properties_of_nonexistent_device()
+        self.test_mount_nonexistent_device()
+        self.test_unmount_nonexistent_device()