Merge pull request #40 from ctabin/piece-capture-support

Adds captured pieces support

README.md

@@ -218,6 +218,18 @@ The status can simply be retrieved after any move with the code below:
 Status status = game.getStatus();
 ```
 
+### Captured pieces
+
+The easy way to get the captured pieces of a game is simple to use the `JChessGame.getCaptured` method:
+
+```java
+JChessGame game = JChessGame.newGame();
+game.play("e4", "d5", "exd5");
+
+game.getCaptured(Color.WHITE); //empty
+game.getCaptured(Color.BLACK); //contains 1 Pawn entity
+```
+
 ### Import games from PGN files
 
 It is possible to import basic [PGN](https://en.wikipedia.org/wiki/Portable_Game_Notation) files

src/main/java/ch/astorm/jchess/JChessGame.java

@@ -312,6 +312,18 @@ public List<Move> back(int nbMoves) {
         return dropped;
     }
 
+    /**
+     * Returns the captured pieces of the specified {@code Color} based on the current
+     * position move histoy.
+     */
+    public List<Moveable> getCaptured(Color color) {
+        return position.getMoveHistory().stream().
+            map(m -> m.getCapturedEntity()).
+            filter(m -> m!=null).
+            filter(m -> m.getColor()==color).
+            collect(Collectors.toList());
+    }
+
     /**
      * Returns the {@link Color} that has the move.
      */

src/test/java/ch/astorm/jchess/JChessGameTest.java

@@ -9,6 +9,7 @@
 import ch.astorm.jchess.core.entities.Bishop;
 import ch.astorm.jchess.core.entities.King;
 import ch.astorm.jchess.core.entities.Knight;
+import ch.astorm.jchess.core.entities.Pawn;
 import ch.astorm.jchess.core.entities.Queen;
 import ch.astorm.jchess.core.entities.Rook;
 import ch.astorm.jchess.core.rules.RuleManager;
@@ -37,6 +38,8 @@ public void testInitialPosition() {
         JChessGame game = JChessGame.newGame();
         assertNull(game.get("e5"));
         assertNotNull(game.get("a1"));
+        assertTrue(game.getCaptured(Color.WHITE).isEmpty());
+        assertTrue(game.getCaptured(Color.BLACK).isEmpty());
 
         assertEquals(20, game.getAvailableMoves().size());
 
@@ -204,4 +207,17 @@ public void testDrawByStalemate() {
         assertEquals(Status.DRAW_STALEMATE, game.play("Qg6"));
         assertThrows(IllegalStateException.class, () -> game.play("Qg5"));
     }
+
+    @Test
+    public void testCapturedPieces() {
+        JChessGame game = JChessGame.newGame();
+        game.play("e4", "d5", "exd5");
+
+        assertTrue(game.getCaptured(Color.WHITE).isEmpty());
+
+        List<Moveable> capturedBlack = game.getCaptured(Color.BLACK);
+        assertEquals(1, capturedBlack.size());
+        assertEquals(Color.BLACK, capturedBlack.get(0).getColor());
+        assertTrue(capturedBlack.get(0) instanceof Pawn);
+    }
 }