Run the tests in CI, tag the live-API test

.github/workflows/ci.yml

@@ -0,0 +1,23 @@
+name: CI
+
+on:
+  push:
+    branches: [main, master]
+  pull_request:
+
+jobs:
+  build:
+    name: build and test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: "17"
+          cache: maven
+      # EnergyServiceIntegrationTest calls the live NESO Carbon Intensity API.
+      # It is a useful thing to run by hand and a bad thing to gate a merge on:
+      # an outage upstream would fail a build that has nothing wrong with it.
+      # `mvn test` locally still runs everything.
+      - run: ./mvnw -B --no-transfer-progress verify -DexcludedGroups=integration

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Jakub Kierznowski
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -8,6 +8,10 @@
   EV charging decision backend that analyzes UK grid carbon-intensity data and recommends the cleanest charging window in the next 48 hours.
 </p>
 
+<p align="center">
+  <a href="https://github.com/qualv13/CarCharging/actions/workflows/ci.yml"><img src="https://github.com/qualv13/CarCharging/actions/workflows/ci.yml/badge.svg" alt="CI"></a>
+</p>
+
 <p align="center">
   <a href="https://github.com/qualv13/CarCharging"><img src="https://img.shields.io/badge/GitHub-CarCharging-181717?style=for-the-badge&logo=github" alt="GitHub"></a>
   <img src="https://img.shields.io/badge/Java-17-ED8B00?style=for-the-badge&logo=openjdk&logoColor=white" alt="Java 17">
@@ -329,18 +333,24 @@ This simplicity is a strength for a focused API utility service.
 
 ## Testing
 
-The Maven configuration includes Spring Boot test support.
+18 tests, run on every push by [CI](.github/workflows/ci.yml).
 
-Run tests with:
+| Class | Covers | Tests |
+| --- | --- | --- |
+| `ChargingServiceTest` | the sliding window over half-hourly slots, including ties and short horizons | 10 |
+| `EnergyServiceTest` | daily mix aggregation with a mocked client | 6 |
+| `CarChargingApplicationTests` | the Spring context loads | 1 |
+| `EnergyServiceIntegrationTest` | the real NESO API, end to end | 1 |
 
 ```bash
-mvn test
+mvn test                                  # everything
+mvn test -DexcludedGroups=integration     # what CI runs
 ```
 
-The repository structure also indicates service-level tests such as:
-- `ChargingServiceTest`
-- `EnergyServiceTest`
-- `EnergyServiceIntegrationTest`
+The last one is tagged `integration` and left out of CI on purpose. It calls
+the live NESO Carbon Intensity API, so an outage upstream would fail a build
+that has nothing wrong with it. Worth running by hand when the client or the
+response shape changes.
 
 ---
 

src/test/java/org/qualv13/carcharging/service/EnergyServiceIntegrationTest.java

@@ -1,6 +1,7 @@
 package org.qualv13.carcharging.service;
 
 import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
 import org.qualv13.carcharging.client.CarbonIntensityClient;
 import org.qualv13.carcharging.model.dto.ChargingWindowDto;
@@ -9,6 +10,10 @@
 
 import java.util.List;
 
+// Talks to the live NESO Carbon Intensity API, so it is excluded from CI:
+// an outage upstream would fail a build that has nothing wrong with it.
+// `mvn test` runs it; `mvn test -DexcludedGroups=integration` does not.
+@Tag("integration")
 class EnergyServiceIntegrationTest {
 
     @Test