Testing MicroProfile Config

LocalTestContext.java

public class LocalTestContext {

    private static final LocalTestContext INSTANCE = new LocalTestContext();

    private final ThreadLocal<Map<String, String>> localTestData = ThreadLocal.withInitial(HashMap::new);

    private LocalTestContext() {
    }

    public void addConfigValue(String key, String value) {
        localTestData.get().put(key, value);
    }

    public String getConfigValue(String key) {
        return localTestData.get().get(key);
    }

    public void reset() {
        localTestData.remove();
    }

    public Set<String> keys() {
        return localTestData.get().keySet();
    }

    public static LocalTestContext getInstance() {
        return INSTANCE;
    }
}

TestConfigSource.java

public class TestConfigSource implements ConfigSource {
    @Override
    public Set<String> getPropertyNames() {
        return LocalTestContext.getInstance().keys();
    }

    @Override
    public String getValue(String propertyName) {
        return LocalTestContext.getInstance().getConfigValue(propertyName);
    }

    @Override
    public String getName() {
        return "LocalTestContext ConfigSource";
    }
}