Merge pull request #10 from ARMmbed/unit-test-infrastructure

AD: Initial test infrastructure

Author: AGlass0fMilk

doc/adr/0002-define-initial-testing-infrastructure.md

@@ -0,0 +1,60 @@
+# 2. Define initial testing infrastructure
+
+Date: 2020-10-28
+
+## Status
+
+Accepted
+
+## Context
+
+To raise the quality of the example maintained in this repository, contributors 
+need a testing infrastructure available to validate new services proposed, 
+extensions or bug fixes. 
+
+### Unit testing 
+
+Unit tests are isolated from the system and should run on desktop machines 
+(Linux, MacOS, Windows). 
+The unit tests will rely on mock and stub of BLE API, the test framework selected 
+must support declaration of these kind of objects. 
+
+Many C++ unit test framework are available (CppUTest, Catch2, Boost.test, 
+google-test, ...) all with their qualities and weaknesses. 
+Due to the use of google test in [Mbed OS](https://github.com/ARMmbed/mbed-os/tree/master/UNITTESTS) 
+we propose to use google-test to unit test Bluetooth services.
+
+### CI integration 
+
+To validate new submissions, it is important to exercise them automatically. 
+Many CI providers exists for open source project (Circle CI, travis, ...). 
+We propose to use Circle CI as it is used to compile ble-example and ble-testsuite
+submissions. It is easy to setup and approved by the ARMmbed organisation 
+
+### Compilers 
+
+GCC and Clang are both available to all machines targeted. 
+We propose to use Clang as it provides better messages in case of compilation failure.
+
+### Code coverage
+
+To ensure tests submitted cover sufficciently the code submitted we propose to use the 
+code coverage solution offered by the selected compiler (Clang).   
+
+### Integration tests
+
+There is no definitive pattern for integration test of Bluetooth services. 
+This should be described and defined in a subsequent architecture decision when consensus has emerged.  
+
+
+## Decision
+
+We will use `google test` to unit test services proposed. The tests will be compiled 
+with `Clang` and will generate a code coverage report when run.
+For pull request validation, the code and test suite will be compiled and run by `Circle CI`. 
+Depending on results and code coverage, the submission will be rejected. 
+
+## Consequences
+
+The base of the test infrastructure should be created, it must be based on google test, 
+be compiled with clang run in Circle CI.