ConnectorValidationUtils checks if parallel devices is > 0

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 - Enhancing `VoltageLevel` with `equals` method [#1063](https://github.com/ie3-institute/PowerSystemDataModel/issues/1063)
+- `ConnectorValidationUtils` checks if parallel devices is > 0 [#1077](https://github.com/ie3-institute/PowerSystemDataModel/issues/1077)
 
 ### Fixed
 - Fixed `MappingEntryies` not getting processed by adding `Getter` methods for record fields [#1084](https://github.com/ie3-institute/PowerSystemDataModel/issues/1084) 

src/main/java/edu/ie3/datamodel/utils/validation/ConnectorValidationUtils.java

@@ -65,6 +65,7 @@ protected static List<Try<Void, InvalidEntityException>> check(ConnectorInput co
 
     List<Try<Void, InvalidEntityException>> exceptions = new ArrayList<>();
     exceptions.add(connectsDifferentNodes(connector));
+    exceptions.add(lessThanOneParallelDevice(connector));
 
     // Further checks for subclasses
     if (LineInput.class.isAssignableFrom(connector.getClass())) {
@@ -443,6 +444,23 @@ private static Try<Void, InvalidEntityException> connectsDifferentNodes(
                 connectorInput));
   }
 
+  /**
+   * Check that the given connector has at least one parallel device.
+   *
+   * @param connectorInput to check
+   * @return a try
+   */
+  private static Try<Void, InvalidEntityException> lessThanOneParallelDevice(
+      ConnectorInput connectorInput) {
+    return Try.ofVoid(
+        connectorInput.getParallelDevices() < 1,
+        () ->
+            new InvalidEntityException(
+                connectorInput.getClass().getSimpleName()
+                    + " needs to have at least one parallel device",
+                connectorInput));
+  }
+
   /**
    * Check if subnets of connector's nodes are correct depending on if they should be equal or not
    *

src/test/groovy/edu/ie3/datamodel/utils/validation/ConnectorValidationUtilsTest.groovy

@@ -62,6 +62,23 @@ class ConnectorValidationUtilsTest extends Specification {
   OlmCharacteristicInput.CONSTANT_CHARACTERISTIC
   )
 
+  def "A ConnectorInput needs at least one parallel device"() {
+    when:
+    def actual = ConnectorValidationUtils.lessThanOneParallelDevice(invalidConnector)
+
+    then:
+    actual.failure
+    actual.exception.get().class == InvalidEntityException
+    actual.exception.get().message.contains(expectedMessage)
+
+    where:
+    invalidConnector                                                  || expectedMessage
+    GridTestData.lineFtoG.copy().parallelDevices(0).build()           || "LineInput needs to have at least one parallel device"
+    GridTestData.lineCtoD.copy().parallelDevices(-1).build()          || "LineInput needs to have at least one parallel device"
+    GridTestData.transformerBtoE.copy().parallelDevices(0).build()    || "Transformer2WInput needs to have at least one parallel device"
+    GridTestData.transformerAtoBtoC.copy().parallelDevices(0).build() || "Transformer3WInput needs to have at least one parallel device"
+  }
+
   def "ConnectorValidationUtils.checkLine() recognizes all potential errors for a line"() {
     when:
     List<Try<Void, InvalidEntityException>> exceptions = ConnectorValidationUtils.check(invalidLine).stream().filter { it -> it.failure }.toList()