5.6 KiB
Testsuite
OSRM comes with a testsuite containing both unit-tests using the BOOST library and cucucmber.js for scenario driven testing.
Unit Tests
TODO write a guide on unit tests.
Cucumber
For a general introduction on cucumber in our testsuite, have a look at the wiki.
This documentation aims to supply a guideline on how to write cucumber tests that test new features introduced into osrm.
Test the feature
It is often tempting to reduce the test to a path and accompanying instructions. Instructions can and will change over the course of improving guidance.
Instructions should only be used when writing a feature located in features/guidance. All other features should avoid using instructions at all.
Write Tests to Scale
OSRM is a navigation engine. Tests should always consider this background.
An important implication is the grid size. If tests use a very small grid size, you run into the chance of instructions being omitted. For example:
Background:
Given the profile "car"
Given a grid size of 10 meters
Scenario: Testbot - Straight Road
Given the node map
| a | b | c | d |
And the ways
| nodes | highway |
| ab | primary |
| bc | primary |
| cd | primary |
When I route I should get
| from | to | route |
| a | d | ab,bc,cd,cd |
In a navigation engine, the instructions
- depart east on ab
- in 10 meters the road name changes to bc
- in 10 meters the road name changes to cd
- you arrived at cd
would be impossible to announce and not helpful at all.
Since no actual choices exist, the route you get could result in ab,cd and simply say depart and arrive.
To prevent such surprises, always consider the availability of other roads and use grid sizes/road lengths that correspond to actually reasonable scenarios in a road network.
Use names
If you specify many nodes in close succession to present a specific road geometry, consider using name to indicate to OSRM that the segment is a single road.
Background:
Given the profile "car"
Given a grid size of 10 meters
Scenario: Testbot - Straight Road
Given the node map
| a | b | c | d |
And the ways
| nodes | highway | name |
| ab | primary | road |
| bc | primary | road |
| cd | primary | road |
When I route I should get
| from | to | route | turns |
| a | d | road,road | depart,arrive |
Guidance guarantees only essential maneuvers. You will always see depart and arrive as well as all turns that are not obvious.
So the following scenario does not change the instructions
Background:
Given the profile "car"
Given a grid size of 10 meters
Scenario: Testbot - Straight Road
Given the node map
| a | b |
| d | c |
And the ways
| nodes | highway | name |
| ab | primary | road |
| bc | primary | road |
| cd | primary | road |
When I route I should get
| from | to | route | turns |
| a | d | road,road | depart,arrive |
but if we modify it to
Background:
Given the profile "car"
Given a grid size of 10 meters
Scenario: Testbot - Straight Road
Given the node map
| a | b | e |
| d | c | |
And the ways
| nodes | highway | name |
| ab | primary | road |
| bc | primary | road |
| cd | primary | road |
| be | primary | turn |
When I route I should get
| from | to | route | turns |
| a | d | road,road,road | depart,continue right,arrive |
Prevent Randomness
Some features in OSRM can result in strange experiences during testcases. To prevent some of these issues, follow the guidelines below.
Use Waypoints
Using grid nodes as waypoints offers the chance of unwanted side effects. OSRM converts the grid into a so called edge-based graph.
Scenario: Testbot - Intersection
Given the node map
| | e | |
| b | a | d |
| | c | |
And the ways
| nodes | highway | oneway |
| ab | primary | yes |
| ac | primary | yes |
| ad | primary | yes |
| ae | primary | yes |
Selecting a as a waypoint results in four possible starting locations. Which one of the routes a,b, a,c, a,d, or a,e is found is pure chance and depends on the order in the static r-tree.
To guarantee discovery, use:
Scenario: Testbot - Intersection
Given the node map
| | | e | | |
| | | 4 | | |
| b | 1 | a | 3 | d |
| | | 2 | | |
| | | c | | |
And the ways
| nodes | highway | oneway |
| ab | primary | yes |
| ac | primary | yes |
| ad | primary | yes |
| ae | primary | yes |
And use 1,2,3, and 4 as starting waypoints. The routes 1,b, 2,c, 3,d, and 4,e can all be discovered.
Allow For Small Offsets
Whenever you are independent of the start location (see use waypoints), the waypoint chosen as start/end location can still influence distances/durations.
If you are testing for a duration metric, allow for a tiny offset to ensure a passing test in the presence of rounding/snapping issues.
Don't Rely on Alternatives
Alternative route discovery is a random feature in itself. The discovery of routes depends on the contraction order of roads and cannot be assumed successful, ever.