TomTom::Matrix: Serialize `BigDecimal` as float

Rails serialises `BigDecimal`s as JSON strings to prevent loss of
precision. The `latitude` and `longitude` columns in `StopArea` are
stored as `BigDecimal`s. The trouble is that TomTom's API requires the
latitude & longitude values to be JSON floats, not strings.

Make a new JSON serialiser that converts the `BigDecimal` coordinates to
float to allow the values to be correctly interpreted by the API.

Refs #6222

2 files changed, 111 insertions, 0 deletions

diff --git a/spec/lib/tom_tom/matrix/request_json_serializer_spec.rb b/spec/lib/tom_tom/matrix/request_json_serializer_spec.rb
new file mode 100644
index 000000000..1fafad302
--- /dev/null
+++ b/spec/lib/tom_tom/matrix/request_json_serializer_spec.rb
@@ -0,0 +1,39 @@
+RSpec.describe TomTom::Matrix::RequestJSONSerializer do
+  describe ".dump" do
+    it "serializes BigDecimal values to floats" do
+      points = [{
+        point: {
+          latitude: 52.50867.to_d,
+          longitude: 13.42879.to_d
+        },
+      }]
+      data = {
+        origins: points,
+        destinations: points
+      }
+
+      expect(
+        TomTom::Matrix::RequestJSONSerializer.dump(data)
+      ).to eq(<<-JSON.delete(" \n"))
+        {
+          "origins": [
+            {
+              "point": {
+                "latitude": 52.50867,
+                "longitude": 13.42879
+              }
+            }
+          ],
+          "destinations": [
+            {
+              "point": {
+                "latitude": 52.50867,
+                "longitude": 13.42879
+              }
+            }
+          ]
+        }
+      JSON
+    end
+  end
+end
diff --git a/spec/lib/tom_tom/matrix_spec.rb b/spec/lib/tom_tom/matrix_spec.rb
index b63ebc70b..605f1d254 100644
--- a/spec/lib/tom_tom/matrix_spec.rb
+++ b/spec/lib/tom_tom/matrix_spec.rb
@@ -77,6 +77,78 @@ RSpec.describe TomTom::Matrix do
     end
   end
 
+  describe "#build_request_body" do
+    it "serializes BigDecimal coordinates to floats" do
+      points = [
+        {
+          point: {
+            latitude: 48.85086.to_d,
+            longitude: 2.36143.to_d
+          },
+        },
+        {
+          point: {
+            latitude: 47.91231.to_d,
+            longitude: 1.87606.to_d
+          },
+        },
+        {
+          point: {
+            latitude: 52.50867.to_d,
+            longitude: 13.42879.to_d
+          },
+        }
+      ]
+
+      expect(
+        matrix.build_request_body(points)
+      ).to eq(<<-JSON.delete(" \n"))
+        {
+          "origins": [
+            {
+              "point": {
+                "latitude": 48.85086,
+                "longitude": 2.36143
+              }
+            },
+            {
+              "point": {
+                "latitude": 47.91231,
+                "longitude": 1.87606
+              }
+            },
+            {
+              "point": {
+                "latitude": 52.50867,
+                "longitude": 13.42879
+              }
+            }
+          ],
+          "destinations": [
+            {
+              "point": {
+                "latitude": 48.85086,
+                "longitude": 2.36143
+              }
+            },
+            {
+              "point": {
+                "latitude": 47.91231,
+                "longitude": 1.87606
+              }
+            },
+            {
+              "point": {
+                "latitude": 52.50867,
+                "longitude": 13.42879
+              }
+            }
+          ]
+        }
+      JSON
+    end
+  end
+
   describe "#extract_costs_to_way_costs!" do
     it "puts distance & time costs in way_costs" do
       way_costs = [