Tools: autotest: suite: add check_parameter_value to to check parma…

…mter is withing a given percentage of the expected value

Tools/autotest/vehicle_test_suite.py

@@ -6271,6 +6271,35 @@ def add_param_value(mav, m):
             return
         raise ValueError("Failed to set parameters (%s)" % want)
 
+    def check_parameter_value(self, name, expected_value, max_error_percent):
+        value = self.get_parameter_direct(name, verbose=False)
+
+        # Convert to ratio and find limits
+        error_ratio = max_error_percent / 100
+        limits = [expected_value * (1 + error_ratio), expected_value * (1 - error_ratio)]
+
+        # Ensure that min and max are always the corret way round
+        upper_limit = max(limits)
+        lower_limit = min(limits)
+
+        # Work out the true error percentage
+        error_percent = math.nan
+        if expected_value != 0:
+            error_percent = abs(1.0 - (value / expected_value)) * 100
+
+        # Check value is within limits
+        if (value > upper_limit) or (value < lower_limit):
+            raise ValueError("%s expected %f ± %f%% (%f to %f) got %s with %f%% error" % (
+                name,
+                expected_value,
+                max_error_percent,
+                lower_limit,
+                upper_limit,
+                value,
+                error_percent))
+
+        self.progress("%s: (%f) check passed %f%% error less than %f%%" % (name, value, error_percent, max_error_percent))
+
     def get_parameter(self, *args, **kwargs):
         return self.get_parameter_direct(*args, **kwargs)