Improve multi-level support and stairs

src/test/java/com/majinnaibu/bukkitplugins/metropolis/AvenueStairwayLayoutTest.java

@@ -71,6 +71,39 @@ class AvenueStairwayLayoutTest {
     assertTrue(flight.roadOpenings().stream().allMatch(step -> step.y() == 76));
   }
 
+  @Test
+  void createsOneCenteredStairFlightPerLogicalPlotOnBothAvenueBorders() {
+    Cuboid twoByTwoPlot = new Cuboid(2, 62, 2, 69, 71, 69);
+
+    List<AvenueStairwayLayout.Flight> flights =
+        AvenueStairwayLayout.forUpperRoadSegments(twoByTwoPlot, 32, 36, 0, 1, 4, 2, 62, 14, 3);
+
+    assertEquals(4, flights.size());
+    assertEquals(
+        new AvenueStairwayLayout.Step(71, 63, 12), flights.get(0).stairBlocks().getFirst());
+    assertEquals(
+        new AvenueStairwayLayout.Step(-1, 63, 12), flights.get(1).stairBlocks().getFirst());
+    assertEquals(
+        new AvenueStairwayLayout.Step(71, 63, 48), flights.get(2).stairBlocks().getFirst());
+    assertEquals(
+        new AvenueStairwayLayout.Step(-1, 63, 48), flights.get(3).stairBlocks().getFirst());
+    assertTrue(flights.stream().allMatch(flight -> flight.stairBlocks().getLast().y() == 76));
+  }
+
+  @Test
+  void appliesStairCadenceToEachLogicalPlotSegment() {
+    Cuboid twoByTwoPlot = new Cuboid(2, 62, 2, 69, 71, 69);
+
+    List<AvenueStairwayLayout.Flight> flights =
+        AvenueStairwayLayout.forUpperRoadSegments(twoByTwoPlot, 32, 36, 0, 2, 4, 2, 62, 14, 3);
+
+    assertEquals(2, flights.size());
+    assertEquals(
+        new AvenueStairwayLayout.Step(71, 63, 48), flights.getFirst().stairBlocks().getFirst());
+    assertEquals(
+        new AvenueStairwayLayout.Step(-1, 63, 48), flights.getLast().stairBlocks().getFirst());
+  }
+
   @Test
   void rejectsAStairRunThatCannotFitWithinThePlotLength() {
     Cuboid plot = new Cuboid(2, 62, 2, 33, 71, 13);

src/test/java/com/majinnaibu/bukkitplugins/metropolis/PlotLevelSupportTest.java

@@ -0,0 +1,55 @@
+/*
+This file is part of Metropolis.
+
+Metropolis is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Metropolis is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with Metropolis. If not, see <https://www.gnu.org/licenses/agpl-3.0.txt>.
+*/
+
+package com.majinnaibu.bukkitplugins.metropolis;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Set;
+
+import org.junit.jupiter.api.Test;
+
+class PlotLevelSupportTest {
+  @Test
+  void rejectsUpperPlotWhenAnyLogicalCellBelowIsMissing() {
+    Set<String> generatedCells = Set.of("0:0:0", "0:1:0", "1:0:0");
+
+    assertFalse(
+        PlotLevelSupport.hasCompleteSupport(
+            0, 0, 2, 1, (row, col, level) -> generatedCells.contains(key(row, col, level))));
+  }
+
+  @Test
+  void requiresEveryLogicalCellAtEveryLowerLevel() {
+    Set<String> generatedCells =
+        Set.of("0:0:0", "0:1:0", "1:0:0", "1:1:0", "0:0:1", "0:1:1", "1:0:1", "1:1:1");
+
+    assertTrue(
+        PlotLevelSupport.hasCompleteSupport(
+            0, 0, 2, 2, (row, col, level) -> generatedCells.contains(key(row, col, level))));
+  }
+
+  @Test
+  void baseLevelDoesNotRequireLowerSupport() {
+    assertTrue(PlotLevelSupport.hasCompleteSupport(3, 4, 2, 0, (row, col, level) -> false));
+  }
+
+  private static String key(int row, int col, int level) {
+    return row + ":" + col + ":" + level;
+  }
+}