Changes Single Coordinate Geoms from Point to LineString, closes #3425.

CHANGELOG.md

@@ -29,6 +29,7 @@
       - fixed a bug that could result in crashes when leaving a ferry directly onto a motorway ramp
       - fixed a bug in the tile plugin that resulted in discovering invalid edges for connections
       - improved error messages when missing files during traffic updates (#3114)
+      - For single coordinate geometries the GeoJSON `Point` encoding was broken. We now always emit `LineString`s even in the one-coordinate-case (backwards compatible) (#3425)
     - Debug Tiles
       - Added support for turn penalties
     - Internals

docs/http.md

@@ -519,7 +519,7 @@ step.
 |------------|--------------------------------------------------------------------|
 | polyline   | [polyline](https://www.npmjs.com/package/polyline) with precision 5 in [latitude,longitude] encoding |
 | polyline6  | [polyline](https://www.npmjs.com/package/polyline) with precision 6 in [latitude,longitude] encoding |
-| geojson    | [GeoJSON `LineString`](http://geojson.org/geojson-spec.html#linestring) or [GeoJSON `Point`](http://geojson.org/geojson-spec.html#point) if it is only one coordinate (not wrapped by a GeoJSON feature)|
+| geojson    | [GeoJSON `LineString`](http://geojson.org/geojson-spec.html#linestring) |
 
 - `name`: The name of the way along which travel proceeds.
 - `ref`: A reference number or code for the way. Optionally included, if ref data is available for the given way.

include/engine/api/json_factory.hpp

@@ -54,22 +54,25 @@ util::json::Object makeGeoJSONGeometry(ForwardIter begin, ForwardIter end)
     auto num_coordinates = std::distance(begin, end);
     BOOST_ASSERT(num_coordinates != 0);
     util::json::Object geojson;
+    geojson.values["type"] = "LineString";
+    util::json::Array coordinates;
     if (num_coordinates > 1)
     {
-        geojson.values["type"] = "LineString";
-        util::json::Array coordinates;
         coordinates.values.reserve(num_coordinates);
-        std::transform(
-            begin, end, std::back_inserter(coordinates.values), &detail::coordinateToLonLat);
-        geojson.values["coordinates"] = std::move(coordinates);
+        auto into = std::back_inserter(coordinates.values);
+        std::transform(begin, end, into, &detail::coordinateToLonLat);
     }
     else if (num_coordinates > 0)
     {
-        geojson.values["type"] = "Point";
-        util::json::Array coordinates;
-        coordinates.values.push_back(detail::coordinateToLonLat(*begin));
-        geojson.values["coordinates"] = std::move(coordinates);
+        // For a single location we create a [location, location] LineString
+        // instead of a single Point making the GeoJSON output consistent.
+        coordinates.values.reserve(2);
+        auto location = detail::coordinateToLonLat(*begin);
+        coordinates.values.push_back(location);
+        coordinates.values.push_back(location);
     }
+    geojson.values["coordinates"] = std::move(coordinates);
+
     return geojson;
 }
 

unit_tests/CMakeLists.txt

@@ -57,7 +57,7 @@ target_include_directories(util-tests PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
 
 target_link_libraries(engine-tests ${ENGINE_LIBRARIES} ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY})
 target_link_libraries(extractor-tests ${EXTRACTOR_LIBRARIES} ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY})
-target_link_libraries(library-tests osrm ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY})
+target_link_libraries(library-tests osrm ${ENGINE_LIBRARIES} ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY})
 target_link_libraries(server-tests osrm ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY})
 target_link_libraries(util-tests ${UTIL_LIBRARIES} ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY})
 

unit_tests/library/json.cpp

@@ -0,0 +1,71 @@
+#include <boost/test/test_case_template.hpp>
+#include <boost/test/unit_test.hpp>
+
+#include "coordinates.hpp"
+#include "equal_json.hpp"
+
+#include "engine/api/json_factory.hpp"
+#include "osrm/coordinate.hpp"
+
+#include <iterator>
+#include <vector>
+
+using namespace osrm;
+
+BOOST_AUTO_TEST_SUITE(json)
+
+BOOST_AUTO_TEST_CASE(test_json_linestring)
+{
+    const std::vector<util::Coordinate> locations{get_dummy_location(),  //
+                                                  get_dummy_location(),  //
+                                                  get_dummy_location()}; //
+
+    auto geom = engine::api::json::makeGeoJSONGeometry(begin(locations), end(locations));
+
+    const auto type = geom.values["type"].get<util::json::String>().value;
+    BOOST_CHECK_EQUAL(type, "LineString");
+
+    const auto coords = geom.values["coordinates"].get<util::json::Array>().values;
+    BOOST_CHECK_EQUAL(coords.size(), 3); // array of three location arrays
+
+    for (const auto each : coords)
+    {
+        const auto loc = each.get<util::json::Array>().values;
+        BOOST_CHECK_EQUAL(loc.size(), 2);
+
+        const auto lon = loc[0].get<util::json::Number>().value;
+        const auto lat = loc[1].get<util::json::Number>().value;
+
+        (void)lon;
+        (void)lat;
+        // cast fails if type do not match
+    }
+}
+
+BOOST_AUTO_TEST_CASE(test_json_single_point)
+{
+    const std::vector<util::Coordinate> locations{get_dummy_location()};
+
+    auto geom = engine::api::json::makeGeoJSONGeometry(begin(locations), end(locations));
+
+    const auto type = geom.values["type"].get<util::json::String>().value;
+    BOOST_CHECK_EQUAL(type, "LineString");
+
+    const auto coords = geom.values["coordinates"].get<util::json::Array>().values;
+    BOOST_CHECK_EQUAL(coords.size(), 2); // array of two location arrays
+
+    for (const auto each : coords)
+    {
+        const auto loc = each.get<util::json::Array>().values;
+        BOOST_CHECK_EQUAL(loc.size(), 2);
+
+        const auto lon = loc[0].get<util::json::Number>().value;
+        const auto lat = loc[1].get<util::json::Number>().value;
+
+        (void)lon;
+        (void)lat;
+        // cast fails if type do not match
+    }
+}
+
+BOOST_AUTO_TEST_SUITE_END()