anchor.diff:        });
   
         test("endAt", () async {
  -        var ref = database.ref("flowers");
  -        await ref.remove();
  +        ref = database.ref("flowers");
           ref.push("rose");
           ref.push("tulip");
           ref.push("chicory");
  
positive.code: 
        test("parent", () {
          var childRef = ref.child("text");
          expect(childRef, isNotNull);
          expect(childRef.parent.toString(), "${databaseUrl}/messages");
        });
  
  
negative.code:         expect(filteredFlowers.values.contains("chicory"), isTrue);
          expect(filteredFlowers.values.contains("sunflower"), isFalse);
        });
  
        test("startAt", () async {
          ref = database.ref("flowers");
          ref.push("rose");
          ref.push("tulip");
          ref.push("chicory");
          ref.push("sunflower");
  
          var event = await ref.orderByValue().startAt("rose").once("value");
          var filteredFlowers = event.snapshot.val();
  
          expect(filteredFlowers.length, 3);
          expect(filteredFlowers.values.contains("sunflower"), isTrue);
          expect(filteredFlowers.values.contains("chicory"), isFalse);
        });
  
        test("equalTo", () async {
          ref = database.ref("flowers");
          ref.push("rose");
          ref.push("tulip");
  
          var event = await ref.orderByValue().equalTo("rose").once("value");
          var flower = event.snapshot.val();
  
          expect(flower, isNotNull);
          expect(flower.length, 1);
          expect(flower.values.first, "rose");
        });
      });
    });
  }
  