Ledger has three types of tests.
unit tests are low-level tests written against the smallest testable parts of the code. Tests for some_class.{h,cc} are placed side-by-side the code being tested, in a some_class_unittest.cc file.
Unit tests are regular Google Test tests, although most of them use our own TestWithMessageLoop base class to conveniently run delayed tasks with a timeout, ensuring that a failing test does not hang forever.
All unit tests in the Ledger tree are built into a single ledger_unittests binary, that by default can be executed on Fuchsia by running /system/test/ledger_unittests.
integration tests are written against client-facing FIDL services exposed by Ledger, although these services still run in the same process as the test code.
Integration tests inherit from IntegrationTest and are placed under /bin/ledger/tests/integration.
All integration tests in the Ledger tree are built into a single ledger_integration_tests binary, that by default can be executed on Fuchsia by running /system/test/ledger_integration_tests. Some end-to-end tests (synchronization tests, see below) are also run as integration tests using fake implementations of cloud services.
End-to-end tests are also written against client-facing FIDL services exposed by Ledger, but in this case the test code runs in a separate process, and connects to Ledger the same way any other client application would do. This is the highest-level way of testing that exercises all of the Ledger stack.
End-to-end tests exercising only the local part of the Ledger are in /bin/ledger/tests/e2e_local. Synchronization end-to-end tests exercising multi-device synchronization are in /bin/ledger/tests/e2e_sync and compiled both as end-to-end tests exercising real cloud services, and as integration tests using fake services.
All local application tests in the Ledger tree are built into a single ledger_e2e_local binary, that by default can be executed on Fuchsia by running /system/test/ledger_e2e_local. Synchronization tests are built into a single ledger_e2e_sync binary, that by default can be executed on Fuchsia by running /system/test/disabled/ledger_e2e_sync.
