Testing

This page covers how the IoT DC3 backend layers its tests, when a test is required, and which command runs each layer. By the end you'll know how to pick the right test type, run unit, integration, and E2E tests locally, and tell what kind of test a change needs before it counts as done.

You are here: you've read the development overview and conventions, and you want to validate a change to mergeable quality. Testing tips specific to writing drivers are in driver authoring.

Why layer the tests

Heavier is not better. An assertion can catch a logic error in milliseconds — that's no reason to spin up a PostgreSQL container to confirm it. But pure mocks can't exercise cross-service message contracts or time-series persistence, so IoT DC3 splits testing into three layers. Lower layers are faster, more numerous, and more isolated; higher layers are slower, fewer, and closer to the real chain:

• Unit tests are the most numerous and the fastest. They check isolated business logic without starting the Spring context.
• Integration tests use Testcontainers to spin up real PostgreSQL/TimescaleDB, RabbitMQ, and MQTT, exercising cross-component collaboration — DAL, gRPC, and messaging.
• E2E tests are the fewest. They cover end-to-end business chains (command dispatch, event routing, time-series table operations). They're off by default and require an environment variable to run.

The rule for picking a layer: use a unit test if you can avoid external dependencies; reach for integration only when a real container is needed to reproduce the behavior (SQL, messaging, gRPC contracts); reserve E2E for validating the entire chain.

The three-layer pyramid and its commands

The diagram maps the three layers, each layer's scope and startup mode, and the command that triggers it. The executors (Surefire/Failsafe) and the gate (DC3_E2E) decide which layers a single mvn run reaches.

Integration and E2E require a container runtime

Both make test-it and make test-e2e use Testcontainers to start PostgreSQL/TimescaleDB, RabbitMQ, and other containers at runtime, so a working container runtime (podman or Docker) must be present locally. E2E additionally boots a full set of real dependencies on a shared Docker network. Without a container runtime these two commands fail outright rather than skip — make test (pure unit) is unaffected.

The table below compares each layer's goal, executor, and tech stack (reference only; the prose above is authoritative on detail):

Layer	Goal	Executor / Gate	Technical approach
Unit tests	Quickly verify isolated business logic	Surefire	JUnit 5, Mockito 5, AssertJ; Reactor StepVerifier for reactive verification
Integration tests	Verify real infrastructure and cross-module collaboration	Failsafe; *IT.java	Testcontainers, gRPC InProcess, RabbitMQ harness
E2E tests	Verify end-to-end business chains	@EnabledIfEnvironmentVariable(named = "DC3_E2E")	dc3-e2e, Testcontainers (shared Docker network)

How to run it locally

Backend commands go through the Makefile under iot-dc3/. The four most common:

make test                 # Unit tests (Surefire)
make test-it              # Integration tests (Failsafe + Testcontainers; needs a container runtime)
make test-e2e             # E2E: equivalent to DC3_E2E=true mvn -pl dc3-e2e -am -Pe2e verify
make coverage             # Aggregated JaCoCo report (dc3-coverage -am verify)

make test-e2e already sets DC3_E2E=true and runs -Pe2e only on the dc3-e2e module, so you don't need to export the environment variable by hand. To run a single module or a single case, call Maven directly:

# Unit tests for a specific module
mvn -s .mvn/settings.xml test -pl dc3-common/dc3-common-manager

# A single test class / a single test method
mvn -s .mvn/settings.xml test -pl dc3-common/dc3-common-manager -Dtest=DeviceControllerTest
mvn -s .mvn/settings.xml test -pl dc3-common/dc3-common-public -Dtest="RTest#testOkWithData"

After make coverage finishes, the aggregated report lands at:

dc3-coverage/target/site/jacoco-aggregate/index.html

Why Failsafe points to outputDirectory

The parent POM configures Failsafe with classesDirectory=${project.build.outputDirectory}. Spring Boot repackages a module's artifact into an executable fat jar, which can't be loaded directly on the Failsafe classpath; pointing the test run at the unrepackaged, ordinary compiled classes is what lets the classes under test load correctly. Keep this in mind when writing integration tests for executable modules like drivers.

Frontend test commands

The frontend (iot-dc3-web/) uses pnpm + Vitest (unit/api/component/view) and Playwright (E2E), independent of the backend:

Vitest suites

pnpm test                 # All Vitest suites
pnpm test:unit            # tests/unit
pnpm test:api             # tests/api
pnpm test:component       # tests/component
pnpm test:views           # tests/views
pnpm test:guard           # tests/guardrails (AI coding guardrails)
pnpm test:ci              # vitest run --coverage (CI gate)

Playwright E2E

pnpm test:e2e             # headless chromium
pnpm test:e2e:headed      # Visible browser (E2E_HEADLESS=false)

When a test is mandatory

The core convention: for a bug fix, first write a failing test that reproduces it, then fix. Turn "this bug no longer occurs" into an executable test that's red right now; the loop only closes when the fix turns it green. Other changes get tests in proportion to risk:

Change type	Requirement
Bug fix	First add a regression test that reproduces the problem, then implement the fix
New feature / behavior change	Add unit tests, and integration tests as risk warrants
Refactoring	Preserve existing coverage; add contract tests for implicit contracts
DAL / SQL change	Add Testcontainers tests and run make test-it
gRPC proto change	Update the server, client, and contract tests in sync
Docs-only / formatting change	No Java tests needed; a docs build or format check suffices

Reusable test infrastructure

The dc3-common-test module gathers the containers and base classes shared across modules, so each module doesn't build its own. Integration tests reuse these singleton containers and harnesses directly:

Tool	Purpose
PgTimescaleContainer	Singleton timescale/timescaledb-ha:pg18 container, for database and time-series table tests
RabbitContainer	RabbitMQ container, for message publish, confirm, and consume tests
MqttContainer	MQTT container, for MQTT driver tests
GrpcInProcessExtension	JUnit 5 extension: one in-process gRPC server + managed channel per test
RabbitTestHarness	Send and receive RabbitMQ within tests, with awaitTrue() backed by Awaitility
FixedClockConfig	@TestConfiguration that pins the Clock bean to a deterministic instant

Two contract-test base classes guard cross-cutting conventions:

• EnumContractTest<E>: via @TestFactory, checks that enum getIndex() is unique, ofIndex() round-trips, and constant names stay stable.
• SecretFieldContractTest: checks that sensitive fields such as apiKey, password, secret, and token don't leak through @ToString or serialization.

Time, randomness, and waiting

Inject java.time.Clock instead of calling LocalDateTime.now() directly; use FixedClockConfig when you need fixed time. Use Awaitility for async waits — never bare Thread.sleep. Use WebTestClient for WebFlux, not MockMvc; use an in-process channel for gRPC, and don't open a real socket.

Coverage gate

make coverage aggregates JaCoCo data from every module, gated by the thresholds in dc3-coverage/pom.xml:

Metric	Current threshold
Line coverage	coverage.line.minimum = 0.20 (20%)
Branch coverage	coverage.branch.minimum = 0.15 (15%)

The thresholds are deliberately modest for now, to keep progress moving while the test suite is still expanding. The check looks only at the static minimum — any metric below the table above blocks the change, with no comparison against a historical baseline. When raising a threshold, submit tests that support the new bar rather than just bumping the number.

CI workflows

PRs and pushes run tests across three GitHub Actions workflows, one-to-one with the local commands:

Workflow	Trigger	Main task
ci.yml	push / PR to develop, release, main	Fast compile
test.yml	push / PR to develop, release, main	Unit, integration, coverage
e2e.yml	push to develop, release, main or manual trigger	E2E

Before merging, confirm: the unit and integration jobs pass; coverage isn't below the dc3-coverage/pom.xml thresholds (below blocks); and for behavior changes, the description states what's been verified and what risks remain.

Further reading

• Development overview and conventions — overall conventions and command entry points for secondary development
• Driver authoring — how to add the protocol layer and integration tests when deriving a new driver
• Environment variables — dependency hosts and ports needed to run Java locally