as: Abstract percentages and concentration parsing

These kind of of validation checks are so common and might appear even
more as the schema grows. In the same way that definitions are used in
the JSON schema for defining these types, here I've abstracted them to
separate functions to facilitate the maintenance down the road.

I've also added some test to increase coverage and explicitly test the
latest additions.

pkg/messageprocessors/normalizedpayload/uplink.go

@@ -141,6 +141,24 @@ func parseNumber(selector func(dst *Measurement) **float64, vals ...fieldValidat
 	}
 }
 
+// parsePercentage parses and validates a percentage.
+func parsePercentage(selector func(dst *Measurement) **float64) fieldParser {
+	return parseNumber(
+		selector,
+		minimum(0.0),
+		maximum(100.0),
+	)
+}
+
+// parseConcentration parses and validates a concentration. Concentration must be in ppm between 0 and 1000000.
+func parseConcentration(selector func(dst *Measurement) **float64) fieldParser {
+	return parseNumber(
+		selector,
+		minimum(0.0),
+		maximum(1000000.0),
+	)
+}
+
 // minimum returns a field validator that checks the inclusive minimum.
 func minimum[T constraints.Ordered](min T) fieldValidator[T] {
 	return func(v T, path string) error {
@@ -212,12 +230,10 @@ var fieldParsers = map[string]fieldParser{
 		},
 		minimum(0.0),
 	),
-	"soil.moisture": parseNumber(
+	"soil.moisture": parsePercentage(
 		func(dst *Measurement) **float64 {
 			return &dst.Soil.Moisture
 		},
-		minimum(0.0),
-		maximum(100.0),
 	),
 	"soil.temperature": parseNumber(
 		func(dst *Measurement) **float64 {
@@ -239,26 +255,20 @@ var fieldParsers = map[string]fieldParser{
 		minimum(0.0),
 		maximum(14.0),
 	),
-	"soil.n": parseNumber(
+	"soil.n": parseConcentration(
 		func(dst *Measurement) **float64 {
 			return &dst.Soil.Nitrogen
 		},
-		minimum(0.0),
-		maximum(1000000.0),
 	),
-	"soil.p": parseNumber(
+	"soil.p": parseConcentration(
 		func(dst *Measurement) **float64 {
 			return &dst.Soil.Phosphorus
 		},
-		minimum(0.0),
-		maximum(1000000.0),
 	),
-	"soil.k": parseNumber(
+	"soil.k": parseConcentration(
 		func(dst *Measurement) **float64 {
 			return &dst.Soil.Potassium
 		},
-		minimum(0.0),
-		maximum(1000000.0),
 	),
 	"air": object(
 		func(dst *Measurement) *Air {
@@ -271,12 +281,10 @@ var fieldParsers = map[string]fieldParser{
 		},
 		minimum(-273.15),
 	),
-	"air.relativeHumidity": parseNumber(
+	"air.relativeHumidity": parsePercentage(
 		func(dst *Measurement) **float64 {
 			return &dst.Air.RelativeHumidity
 		},
-		minimum(0.0),
-		maximum(100.0),
 	),
 	"air.pressure": parseNumber(
 		func(dst *Measurement) **float64 {
@@ -285,12 +293,10 @@ var fieldParsers = map[string]fieldParser{
 		minimum(900.0),
 		maximum(1100.0),
 	),
-	"air.co2": parseNumber(
+	"air.co2": parseConcentration(
 		func(dst *Measurement) **float64 {
 			return &dst.Air.CO2
 		},
-		minimum(0.0),
-		maximum(1000000.0),
 	),
 	"air.lightIntensity": parseNumber(
 		func(dst *Measurement) **float64 {

pkg/messageprocessors/normalizedpayload/uplink_test.go

@@ -62,6 +62,35 @@ func TestUplink(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "one soil nutrient concentration",
+			normalizedPayload: []*structpb.Struct{
+				{
+					Fields: map[string]*structpb.Value{
+						"soil": {
+							Kind: &structpb.Value_StructValue{
+								StructValue: &structpb.Struct{
+									Fields: map[string]*structpb.Value{
+										"n": {
+											Kind: &structpb.Value_NumberValue{
+												NumberValue: 999999.99,
+											},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			expected: []normalizedpayload.Measurement{
+				{
+					Soil: normalizedpayload.Soil{
+						Nitrogen: float64Ptr(999999.99),
+					},
+				},
+			},
+		},
 		{
 			name: "two air temperatures",
 			normalizedPayload: []*structpb.Struct{
@@ -122,6 +151,39 @@ func TestUplink(t *testing.T) {
 				{},
 			},
 		},
+		{
+			name: "above 100 percent soil moisture",
+			normalizedPayload: []*structpb.Struct{
+				{
+					Fields: map[string]*structpb.Value{
+						"soil": {
+							Kind: &structpb.Value_StructValue{
+								StructValue: &structpb.Struct{
+									Fields: map[string]*structpb.Value{
+										"moisture": {
+											Kind: &structpb.Value_NumberValue{
+												NumberValue: 120,
+											},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			expected: []normalizedpayload.Measurement{
+				{},
+			},
+			expectedValidationErrors: [][]error{
+				{
+					normalizedpayload.ErrFieldMaximum.WithAttributes(
+						"path", "soil.moisture",
+						"maximum", 100.0,
+					),
+				},
+			},
+		},
 		{
 			name: "below absolute zero",
 			normalizedPayload: []*structpb.Struct{