Default implementation of under/over speed checks (#382)

* Default implementation of under/over speed checks

* Update comment, remove requirement for float conversion

* Fan test coverage

sonic_platform_base/fan_base.py

@@ -66,6 +66,52 @@ def get_speed_tolerance(self):
         """
         raise NotImplementedError
 
+    def is_under_speed(self):
+        """
+        Calculates if the fan speed is under the tolerated low speed threshold
+
+        Default calculation requires get_speed_tolerance to be implemented, and checks
+        if the current fan speed (expressed as a percentage) is lower than <get_speed_tolerance>
+        percent below the target fan speed (expressed as a percentage)
+
+        Returns:
+            A boolean, True if fan speed is under the low threshold, False if not
+        """
+        speed = self.get_speed()
+        target_speed = self.get_target_speed()
+        tolerance = self.get_speed_tolerance()
+
+        for param, value in (('speed', speed), ('target speed', target_speed), ('speed tolerance', tolerance)):
+            if not isinstance(value, int):
+                raise TypeError(f'Fan {param} is not an integer value: {param}={value}')
+            if value < 0 or value > 100:
+                raise ValueError(f'Fan {param} is not a valid percentage value: {param}={value}')
+
+        return speed * 100 < target_speed * (100 - tolerance)
+
+    def is_over_speed(self):
+        """
+        Calculates if the fan speed is over the tolerated high speed threshold
+
+        Default calculation requires get_speed_tolerance to be implemented, and checks
+        if the current fan speed (expressed as a percentage) is higher than <get_speed_tolerance>
+        percent above the target fan speed (expressed as a percentage)
+
+        Returns:
+            A boolean, True if fan speed is over the high threshold, False if not
+        """
+        speed = self.get_speed()
+        target_speed = self.get_target_speed()
+        tolerance = self.get_speed_tolerance()
+
+        for param, value in (('speed', speed), ('target speed', target_speed), ('speed tolerance', tolerance)):
+            if not isinstance(value, int):
+                raise TypeError(f'Fan {param} is not an integer value: {param}={value}')
+            if value < 0 or value > 100:
+                raise ValueError(f'Fan {param} is not a valid percentage value: {param}={value}')
+
+        return speed * 100 > target_speed * (100 + tolerance)
+
     def set_speed(self, speed):
         """
         Sets the fan speed

tests/fan_base_test.py

@@ -0,0 +1,158 @@
+'''
+Test FanBase module
+'''
+
+from unittest import mock
+from sonic_platform_base.fan_base import FanBase
+
+class TestFanBase:
+    '''
+    Collection of FanBase test methods
+    '''
+
+    @staticmethod
+    def test_is_under_speed():
+        '''
+        Test fan.is_under_speed default implementation
+        '''
+        fan = FanBase()
+        fan.get_speed = mock.MagicMock(return_value=100)
+        fan.get_target_speed = mock.MagicMock(return_value=50)
+        fan.get_speed_tolerance = mock.MagicMock(return_value=10)
+
+        for func in (fan.get_speed, fan.get_target_speed, fan.get_speed_tolerance):
+            return_val = func()
+
+            # Check type and bounds errors
+            for value, exc_type in ((None, TypeError), (-1, ValueError), (101, ValueError)):
+                func.return_value = value
+                expected_exception = False
+                try:
+                    fan.is_under_speed()
+                except Exception as exc:
+                    expected_exception = isinstance(exc, exc_type)
+                assert expected_exception
+
+            # Reset function return value
+            func.return_value = return_val
+
+        # speed=100, minimum tolerated speed=45, not under speed
+        assert not fan.is_under_speed()
+
+        # speed=46, minimum tolerated speed=45, not under speed
+        fan.get_speed.return_value = 46
+        assert not fan.is_under_speed()
+
+        # speed=45, minimum tolerated speed=45, not under speed
+        fan.get_speed.return_value = 45
+        assert not fan.is_under_speed()
+
+        # speed=44, minimum tolerated speed=45, under speed
+        fan.get_speed.return_value = 44
+        assert fan.is_under_speed()
+
+        # speed=44, minimum tolerated speed=40, not under speed
+        fan.get_speed_tolerance.return_value = 20
+        assert not fan.is_under_speed()
+
+        # speed=41, minimum tolerated speed=40, not under speed
+        fan.get_speed.return_value = 41
+        assert not fan.is_under_speed()
+
+        # speed=40, minimum tolerated speed=40, not under speed
+        fan.get_speed.return_value = 40
+        assert not fan.is_under_speed()
+
+        # speed=39, minimum tolerated speed=40, under speed
+        fan.get_speed.return_value = 39
+        assert fan.is_under_speed()
+
+        # speed=1, minimum tolerated speed=40, under speed
+        fan.get_speed.return_value = 1
+        assert fan.is_under_speed()
+
+    @staticmethod
+    def test_is_over_speed():
+        '''
+        test fan.is_over_speed default implementation
+        '''
+        fan = FanBase()
+        fan.get_speed = mock.MagicMock(return_value=1)
+        fan.get_target_speed = mock.MagicMock(return_value=50)
+        fan.get_speed_tolerance = mock.MagicMock(return_value=10)
+
+        for func in (fan.get_speed, fan.get_target_speed, fan.get_speed_tolerance):
+            return_val = func()
+
+            # Check type and bounds errors
+            for value, exc_type in ((None, TypeError), (-1, ValueError), (101, ValueError)):
+                func.return_value = value
+                expected_exception = False
+                try:
+                    fan.is_under_speed()
+                except Exception as exc:
+                    expected_exception = isinstance(exc, exc_type)
+                assert expected_exception
+
+            # Reset function return value
+            func.return_value = return_val
+
+        # speed=1, maximum tolerated speed=55, not over speed
+        assert not fan.is_over_speed()
+
+        # speed=54, maximum tolerated speed=55, not over speed
+        fan.get_speed.return_value = 54
+        assert not fan.is_over_speed()
+
+        # speed=55, maximum tolerated speed=55, not over speed
+        fan.get_speed.return_value = 55
+        assert not fan.is_over_speed()
+
+        # speed=56, maximum tolerated speed=55, over speed
+        fan.get_speed.return_value = 56
+        assert fan.is_over_speed()
+
+        # speed=56, maximum tolerated speed=60, not over speed
+        fan.get_speed_tolerance.return_value = 20
+        assert not fan.is_over_speed()
+
+        # speed=59, maximum tolerated speed=60, not over speed
+        fan.get_speed.return_value = 59
+        assert not fan.is_over_speed()
+
+        # speed=60, maximum tolerated speed=60, not over speed
+        fan.get_speed.return_value = 60
+        assert not fan.is_over_speed()
+
+        # speed=61, maximum tolerated speed=60, over speed
+        fan.get_speed.return_value = 61
+        assert fan.is_over_speed()
+
+        # speed=100, maximum tolerated speed=60, over speed
+        fan.get_speed.return_value = 100
+        assert fan.is_over_speed()
+
+    @staticmethod
+    def test_fan_base():
+        '''
+        Verify unimplemented methods
+        '''
+        fan = FanBase()
+        not_implemented_methods = [
+            (fan.get_direction,),
+            (fan.get_speed,),
+            (fan.get_target_speed,),
+            (fan.get_speed_tolerance,),
+            (fan.set_speed, 50),
+            (fan.set_status_led, 'green'),
+            (fan.get_status_led,)]
+
+        for method in not_implemented_methods:
+            expected_exception = False
+            try:
+                func = method[0]
+                args = method[1:]
+                func(*args)
+            except Exception as exc:
+                expected_exception = isinstance(exc, NotImplementedError)
+            assert expected_exception