feat: New rule - SingleShapePointValidator for flagging shapes with a single shape point

main/src/main/java/org/mobilitydata/gtfsvalidator/validator/SingleShapePointValidator.java

@@ -0,0 +1,69 @@
+package org.mobilitydata.gtfsvalidator.validator;
+
+import static org.mobilitydata.gtfsvalidator.notice.SeverityLevel.WARNING;
+
+import java.util.HashMap;
+import java.util.Map;
+import javax.inject.Inject;
+import org.mobilitydata.gtfsvalidator.annotation.GtfsValidationNotice;
+import org.mobilitydata.gtfsvalidator.annotation.GtfsValidator;
+import org.mobilitydata.gtfsvalidator.notice.NoticeContainer;
+import org.mobilitydata.gtfsvalidator.notice.ValidationNotice;
+import org.mobilitydata.gtfsvalidator.table.GtfsShape;
+import org.mobilitydata.gtfsvalidator.table.GtfsShapeSchema;
+import org.mobilitydata.gtfsvalidator.table.GtfsShapeTableContainer;
+
+/**
+ * Validates that every shape (identified by shape_id) has more than one shape_point
+ *
+ * <p>Generated notice: {@link SingleShapePointNotice}
+ */
+@GtfsValidator
+public class SingleShapePointValidator extends FileValidator {
+  private final GtfsShapeTableContainer shapeTable;
+
+  @Inject
+  SingleShapePointValidator(GtfsShapeTableContainer shapeTable) {
+    this.shapeTable = shapeTable;
+  }
+
+  @Override
+  public void validate(NoticeContainer noticeContainer) {
+    Map<String, Integer> shapePointCounts = new HashMap<>();
+    Map<String, Integer> shapePointRowNumbers = new HashMap<>();
+    for (GtfsShape shape : shapeTable.getEntities()) {
+      String shapeId = shape.shapeId();
+      shapePointCounts.put(shapeId, shapePointCounts.getOrDefault(shapeId, 0) + 1);
+      shapePointRowNumbers.put(shapeId, shape.csvRowNumber());
+    }
+
+    for (Map.Entry<String, Integer> entry : shapePointCounts.entrySet()) {
+      if (entry.getValue() == 1) {
+        noticeContainer.addValidationNotice(
+            new SingleShapePointNotice(
+                entry.getKey(), shapePointRowNumbers.getOrDefault(entry.getKey(), 0)));
+      }
+    }
+  }
+
+  /**
+   * The shape within `shapes.txt` contains a single shape point.
+   *
+   * <p>A shape should contain more than one shape point to visualize the route
+   */
+  @GtfsValidationNotice(
+      severity = WARNING,
+      files = @GtfsValidationNotice.FileRefs({GtfsShapeSchema.class}))
+  static class SingleShapePointNotice extends ValidationNotice {
+    /** The faulty record's id. */
+    private final String shapeId;
+
+    /** The row number of the faulty record. */
+    private final int csvRowNumber;
+
+    SingleShapePointNotice(String shapeId, int csvRowNumber) {
+      this.shapeId = shapeId;
+      this.csvRowNumber = csvRowNumber;
+    }
+  }
+}

main/src/test/java/org/mobilitydata/gtfsvalidator/validator/SingleShapePointValidatorTest.java

@@ -0,0 +1,59 @@
+package org.mobilitydata.gtfsvalidator.validator;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.ImmutableList;
+import java.util.List;
+import org.junit.Test;
+import org.mobilitydata.gtfsvalidator.notice.NoticeContainer;
+import org.mobilitydata.gtfsvalidator.notice.ValidationNotice;
+import org.mobilitydata.gtfsvalidator.table.GtfsShape;
+import org.mobilitydata.gtfsvalidator.table.GtfsShapeTableContainer;
+
+public class SingleShapePointValidatorTest {
+  public static GtfsShape createShapePoint(
+      int csvRowNumber,
+      String shapeId,
+      double shapePtLat,
+      double shapePtLon,
+      int shapePtSequence,
+      double shapeDistTraveled) {
+    return new GtfsShape.Builder()
+        .setCsvRowNumber(csvRowNumber)
+        .setShapeId(shapeId)
+        .setShapePtLat(shapePtLat)
+        .setShapePtLon(shapePtLon)
+        .setShapePtSequence(shapePtSequence)
+        .setShapeDistTraveled(shapeDistTraveled)
+        .build();
+  }
+
+  private static List<ValidationNotice> generateNotices(List<GtfsShape> shapes) {
+    NoticeContainer noticeContainer = new NoticeContainer();
+    new SingleShapePointValidator(GtfsShapeTableContainer.forEntities(shapes, noticeContainer))
+        .validate(noticeContainer);
+    return noticeContainer.getValidationNotices();
+  }
+
+  @Test
+  public void shapeWithMoreThanOneShapePointShouldNotGenerateNotice() {
+    assertThat(
+            generateNotices(
+                ImmutableList.of(
+                    createShapePoint(1, "first shape id", 45.0d, 45.0d, 1, 0.0d),
+                    createShapePoint(2, "first shape id", 45.1d, 45.0d, 2, 40.0d))))
+        .isEmpty();
+  }
+
+  @Test
+  public void unusedShapeShouldGenerateNotice() {
+    assertThat(
+            generateNotices(
+                ImmutableList.of(
+                    createShapePoint(1, "first shape id", 45.0d, 45.0d, 1, 40.0d),
+                    createShapePoint(2, "first shape id", 45.1d, 45.0d, 2, 40.0d),
+                    createShapePoint(3, "second shape id", 45.0d, 45.0d, 1, 40.0d))))
+        .containsExactly(
+            new SingleShapePointValidator.SingleShapePointNotice("second shape id", 3));
+  }
+}