Added test cases

Signed-off-by: adoerr <me@andreasdoerr.de>

geojson/geohash/geohash_test.go

@@ -23,3 +23,39 @@ func TestABC(t *testing.T) {
 		t.Fatalf("bad geohash %v,%v %v,%v", lat, lon, lat2, lon2)
 	}
 }
+
+// TestEqualsWebserviceHash checks whether an encoded geohash is equal to a
+// geohash encoded by geohash.org for identical lat/lon values.
+func TestEqualsWebserviceHash(t *testing.T) {
+	lat, lon := 27.173117, 78.042122
+	hash, err := Encode(lat, lon, 12)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	hash2 := "tsz6xfswchpu"
+	if hash != hash2 {
+		t.Errorf("geohash should be equal %v, %v", hash, hash2)
+	}
+}
+
+func TestNearbyHasCommonPrefix(t *testing.T) {
+	lat, lon := 27.174583139355413, 78.04258346557617
+	hash, err := Encode(lat, lon, 32)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	lat2, lon2 := 27.174559277910305, 78.04163932800293
+	hash2, err := Encode(lat2, lon2, 32)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// common prefix should be at least of length 7
+	pref := hash[:7]
+	pref2 := hash2[:7]
+	if pref != pref2 {
+		t.Errorf("prefix should be equal %v, %v", pref, pref2)
+	}
+}