diff --git a/observations/observation_test.go b/observations/observation_test.go
new file mode 100644
index 0000000..769e62a
--- /dev/null
+++ b/observations/observation_test.go
@@ -0,0 +1,54 @@
+package observations
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestUnmarshalObservation(t *testing.T) {
+	data := []byte(`
+		{
+			"phenomenonTime": "1970-01-01T00:00:00Z",
+			"receivedTime": "1970-01-01T00:00:00Z",
+			"result": 10
+		}
+	`)
+	var o Observation
+	if err := json.Unmarshal(data, &o); err != nil {
+		t.Fatalf("error during unmarshal json data: %s", err.Error())
+	}
+	if o.PhenomenonTime.Unix() != 0 {
+		t.Fatalf("error during parsing phenomenonTime: %d != 0", o.PhenomenonTime.Unix())
+	}
+}
+
+func TestUnmarshalErroneousObservation(t *testing.T) {
+	data := []byte(`
+		{
+			"phenomenonTime": "1970-01-01T00:00:00Z",
+			"receivedTime": "1970-01-01T00:00:00Z",
+			"result": 500
+		}
+	`)
+	var o Observation
+	if err := json.Unmarshal(data, &o); err != nil {
+		t.Fatalf("error during unmarshal json data: %s", err.Error())
+	}
+	if o.Result != 255 {
+		t.Fatalf("result should be reset to a valid value on overflow")
+	}
+
+	data = []byte(`
+		{
+			"phenomenonTime": "1970-01-01T00:00:00Z",
+			"receivedTime": "1970-01-01T00:00:00Z",
+			"result": -1
+		}
+	`)
+	if err := json.Unmarshal(data, &o); err != nil {
+		t.Fatalf("error during unmarshal json data: %s", err.Error())
+	}
+	if o.Result != 0 {
+		t.Fatalf("result should be reset to a valid value on underflow")
+	}
+}