From f23a70574f58f05fc956f6b2c57e1604dfde8d1c Mon Sep 17 00:00:00 2001
From: Paul Mach <paul@mach.org>
Date: Wed, 30 Oct 2019 09:46:59 -0700
Subject: [PATCH] geojson: return error for missing as well as invalid geometry

---
 geojson/feature.go      |  4 ++++
 geojson/feature_test.go | 20 ++++++++++++++++++++
 geojson/geometry.go     |  8 ++++++--
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/geojson/feature.go b/geojson/feature.go
index ba2d712..dea91f4 100644
--- a/geojson/feature.go
+++ b/geojson/feature.go
@@ -78,6 +78,10 @@ func (f *Feature) UnmarshalJSON(data []byte) error {
 		return fmt.Errorf("geojson: not a feature: type=%s", jf.Type)
 	}
 
+	if jf.Geometry == nil || jf.Geometry.Coordinates == nil {
+		return ErrInvalidGeometry
+	}
+
 	*f = Feature{
 		ID:         jf.ID,
 		Type:       jf.Type,
diff --git a/geojson/feature_test.go b/geojson/feature_test.go
index 295b3bc..549837e 100644
--- a/geojson/feature_test.go
+++ b/geojson/feature_test.go
@@ -146,6 +146,26 @@ func TestUnmarshalFeature(t *testing.T) {
 	}
 }
 
+func TestUnmarshalFeature_missingGeometry(t *testing.T) {
+	t.Run("empty geometry", func(t *testing.T) {
+		rawJSON := `{ "type": "Feature", "geometry": {} }`
+
+		_, err := UnmarshalFeature([]byte(rawJSON))
+		if err != ErrInvalidGeometry {
+			t.Fatalf("incorrect unmarshal error: %v", err)
+		}
+	})
+
+	t.Run("missing geometry", func(t *testing.T) {
+		rawJSON := `{ "type": "Feature" }`
+
+		_, err := UnmarshalFeature([]byte(rawJSON))
+		if err != ErrInvalidGeometry {
+			t.Fatalf("incorrect unmarshal error: %v", err)
+		}
+	})
+}
+
 func TestUnmarshalFeature_BBox(t *testing.T) {
 	rawJSON := `
 	  { "type": "Feature",
diff --git a/geojson/geometry.go b/geojson/geometry.go
index 06712dd..aa7e6f0 100644
--- a/geojson/geometry.go
+++ b/geojson/geometry.go
@@ -7,6 +7,9 @@ import (
 	"github.com/paulmach/orb"
 )
 
+// ErrInvalidGeometry will be returned if a the json of the geometry is invalid.
+var ErrInvalidGeometry = errors.New("geojson: invalid geometry")
+
 // A Geometry matches the structure of a GeoJSON Geometry.
 type Geometry struct {
 	Type        string       `json:"type"`
@@ -105,6 +108,7 @@ func (g *Geometry) UnmarshalJSON(data []byte) error {
 	if err != nil {
 		return err
 	}
+
 	switch jg.Type {
 	case "Point":
 		p := orb.Point{}
@@ -133,10 +137,10 @@ func (g *Geometry) UnmarshalJSON(data []byte) error {
 	case "GeometryCollection":
 		g.Geometries = jg.Geometries
 	default:
-		return errors.New("geojson: invalid geometry")
+		return ErrInvalidGeometry
 	}
 
-	return err
+	return nil
 }
 
 // A Point is a helper type that will marshal to/from a GeoJSON Point geometry.