dht: fix humidity and temperature extraction for DHT22 (#358)

dht/device_internal_test.go

@@ -0,0 +1,46 @@
+package dht
+
+import (
+	"testing"
+)
+
+func TestDeviceType_extractData(t *testing.T) {
+	bitStr := "0000001010001100000000010101111111101110"
+	buf := bitStringToBytes(bitStr)
+
+	tt := []struct {
+		name     string
+		d        DeviceType
+		buf      []byte
+		wantTemp int16
+		wantHum  uint16
+	}{
+		{
+			// temp = 35.1C hum = 65.2%
+			name: "DHT22", d: DHT22, buf: buf, wantTemp: 351, wantHum: 652,
+		},
+	}
+
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			gotTemp, gotHum := tc.d.extractData(tc.buf)
+			if gotTemp != tc.wantTemp {
+				t.Errorf("extractData() gotTemp = %v, want %v", gotTemp, tc.wantTemp)
+			}
+			if gotHum != tc.wantHum {
+				t.Errorf("extractData() gotHum = %v, want %v", gotHum, tc.wantHum)
+			}
+		})
+	}
+}
+
+func bitStringToBytes(s string) []byte {
+	b := make([]byte, (len(s)+(8-1))/8)
+	for i, r := range s {
+		if r < '0' || r > '1' {
+			panic("not in range")
+		}
+		b[i>>3] |= byte(r-'0') << uint(7-i&7)
+	}
+	return b
+}