# Testsuite
OSRM comes with a testsuite containing both unit-tests using the Boost library and cucucmber.js for scenario driven testing.
## Unit Tests
For a general introduction on Boost.Test have a look at [its docs](http://www.boost.org/doc/libs/1_60_0/libs/test/doc/html/index.html).
### Separate Test Binaries
Unit tests should be registered according to the sub-project they're in.
If you want to write tests for utility functions, add them to the utility test binary.
See `CMakeLists.txt` in the unit test directory for how to register new unit tests.
### Using Boost.Test Primitives
There is a difference between only reporting a failed condition and aborting the test right at a failed condition.
Have a look at [`BOOST_CHECK` vs `BOOST_REQUIRE`](http://www.boost.org/doc/libs/1_60_0/libs/test/doc/html/boost_test/utf_reference/testing_tool_ref/assertion_boost_level.html).
Instead of manually checking e.g. for equality, less than, if a function throws etc. use their [corresponding Boost.Test primitives](http://www.boost.org/doc/libs/1_60_0/libs/test/doc/html/boost_test/utf_reference/testing_tool_ref.html).
If you use `BOOST_CHECK_EQUAL` you have to implement `operator<<` for your type so that Boost.Test can print mismatches.
If you do not want to do this, define `BOOST_TEST_DONT_PRINT_LOG_VALUE` (and undef it after the check call) or sidestep it with `BOOST_CHECK(fst == snd);`.
### Test Fixture
If you need to test features on a real dataset (think about this twice: prefer cucumber and dataset-independent tests for their reproducibility and minimality), there is a fixed dataset in `test/data`.
This dataset is a small extract and may not even contain all tags or edge cases.
Furthermore this dataset is not in sync with what you see in up-to-date OSM maps or on the demo server.
See the library tests for how to add new dataset dependent tests.
## Cucumber
For a general introduction on cucumber in our testsuite, have a look at [the wiki](https://github.com/Project-OSRM/osrm-backend/wiki/Cucumber-Test-Suite).
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 |
```
### Test all directions
Modelling a road as roundabout has an implied oneway tag associated with it. In the following case, we can route from `a` to `d` but not from `d` to `a`.
To discover those errors, make sure to check for all allowed directions.
```
Scenario: Enter and Exit mini roundabout with sharp angle # features/guidance/mini-roundabout.feature:37
Given the profile "car" # features/step_definitions/data.js:8
Given a grid size of 10 meters # features/step_definitions/data.js:20
Given the node map # features/step_definitions/data.js:45
"""
a b
c d
"""
And the ways # features/step_definitions/data.js:128
| nodes | highway | name |
| ab | tertiary | MySt |
| bc | roundabout | |
| cd | tertiary | MySt |
When I route I should get # features/step_definitions/routing.js:4
| from | to | route | turns | # |
| a | d | MySt,MySt | depart,arrive | # suppress multiple enter/exit mini roundabouts |
| d | a | MySt,MySt | depart,arrive | # suppress multiple enter/exit mini roundabouts |
Tables were not identical:
| from | to | route | turns | #
| a | d | MySt,MySt | depart,arrive | # suppress multiple enter/exit mini roundabouts |
| (-) d | (-) a | (-) MySt,MySt | (-) depart,arrive | (-) # suppress multiple enter/exit mini roundabouts |
| (+) d | (+) a | (+) | (+) | (+) # suppress multiple enter/exit mini roundabouts |
```
### 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.
### Understanding Turn Restrictions
Adding turn restrictions requires the restriction to follow a very specific format.
We specify them in a table with the header `| type | way:from | way:to | node:via | restriction |`.
It is important that turn restrictions require micro segmentation.
Consider the following scenario:
```
Given the node map:
"""
e
|
a - - b - - c
|
d
"""
And the ways
| nodes | oneway |
| abc | yes |
| ebd | yes |
And the relations
| type | way:from | way:to | node:via | restriction |
| restriction | abc | ebd | b | no_right_turn |
```
The setting looks perfectly fine at first glance. However, it is not well defined.
The forbidden right turn could be either a superfluous addition, forbidding the turn `cb` to `be`, or actually refer to the turn `ab` to `bd` to say that a turn is forbidden here.
To model turn-restrictions correctly and unique, we need to split segments that contribute to the restriction into the smallest possible parts.
E.g. the above scenario could correctly be expressed as:
```
Given the node map:
"""
e
|
a - - b - - c
|
d
"""
And the ways
| nodes | oneway | name |
| ab | yes | abc |
| bc | yes | abc |
| eb | yes | ebd |
| bd | yes | ebd |
And the relations
| type | way:from | way:to | node:via | restriction |
| restriction | ab | bd | b | no_right_turn |
```
Unless this format is used, OSRM will omit the (then ambiguous) turn restrictions and ignore them.