Fix GeoPoint field values with a zero coordinate failing input validation (#3018)

Fix the regression introduced in #2784: a `GeoPoint` where at least one of the coordinates is zero doesn't marshal properly. This is because zeroes happen to be serialized as `undefined` (presumably because protos normally treat zero values and the absence of a value interchangeably) which then fails the strict input validation in `GeoPoint`.

Fixes #3006.

Author: var-const

packages/firestore/src/api/user_data_writer.ts

@@ -75,10 +75,7 @@ export class UserDataWriter<T = firestore.DocumentData> {
       case TypeOrder.RefValue:
         return this.convertReference(value.referenceValue!);
       case TypeOrder.GeoPointValue:
-        return new GeoPoint(
-          value.geoPointValue!.latitude!,
-          value.geoPointValue!.longitude!
-        );
+        return this.convertGeoPoint(value.geoPointValue!);
       case TypeOrder.ArrayValue:
         return this.convertArray(value.arrayValue!);
       case TypeOrder.ObjectValue:
@@ -96,6 +93,13 @@ export class UserDataWriter<T = firestore.DocumentData> {
     return result;
   }
 
+  private convertGeoPoint(value: api.LatLng): GeoPoint {
+    return new GeoPoint(
+      normalizeNumber(value.latitude),
+      normalizeNumber(value.longitude)
+    );
+  }
+
   private convertArray(arrayValue: api.ArrayValue): unknown[] {
     return (arrayValue.values || []).map(value => this.convertValue(value));
   }

packages/firestore/test/integration/api/type.test.ts

@@ -62,15 +62,23 @@ apiDescribe('Firestore', (persistence: boolean) => {
   it('can read and write geo point fields', () => {
     return withTestDoc(persistence, doc => {
       return doc
-        .set({ geopoint: new GeoPoint(1.23, 4.56) })
+        .set({
+          geopoint1: new GeoPoint(1.23, 4.56),
+          geopoint2: new GeoPoint(0, 0)
+        })
         .then(() => {
           return doc.get();
         })
         .then(docSnapshot => {
-          const latLong = docSnapshot.data()!['geopoint'];
+          const latLong = docSnapshot.data()!['geopoint1'];
           expect(latLong instanceof GeoPoint).to.equal(true);
           expect(latLong.latitude).to.equal(1.23);
           expect(latLong.longitude).to.equal(4.56);
+
+          const zeroLatLong = docSnapshot.data()!['geopoint2'];
+          expect(zeroLatLong instanceof GeoPoint).to.equal(true);
+          expect(zeroLatLong.latitude).to.equal(0);
+          expect(zeroLatLong.longitude).to.equal(0);
         });
     });
   });