diff --git a/src/main/java/ByteGrayColor.java b/src/main/java/ByteGrayColor.java
index 1ae5455dc031bb6bdaafc42761db11c3a9ed784e..e7783125b9e5b4be4a377b743b1e4ff670af659a 100644
--- a/src/main/java/ByteGrayColor.java
+++ b/src/main/java/ByteGrayColor.java
@@ -10,8 +10,15 @@ public class ByteGrayColor implements GrayColor {
     private static final int MAXIMUM_GRAY_LEVEL = 255;
     private static final int OPACITY = 1;
 
+    // TODO : rajouter constantes publique BLACK et WHITE
+
     private final int grayLevel;
 
+
+    public ByteGrayColor(){
+       this.grayLevel = MINIMUM_GRAY_LEVEL;
+    }
+
     public ByteGrayColor(int grayLevel) {
         // TODO : Corriger l'initialisation de la propriété grayLevel de l'instance.
         this.grayLevel = 0;
diff --git a/src/test/java/ByteGrayColorTest.java b/src/test/java/ByteGrayColorTest.java
index 5837aa12d26479d5c4380349d42cc8c2e546cad7..ce60ed89f0043dbb8f1878ae9ae4448c0a182034 100644
--- a/src/test/java/ByteGrayColorTest.java
+++ b/src/test/java/ByteGrayColorTest.java
@@ -18,4 +18,37 @@ public class ByteGrayColorTest {
     assertThat(color1.getLuminosity()).isCloseTo(.25, within(.01));
     assertThat(color2.getLuminosity()).isCloseTo(.75, within(.01));
   }
-}
\ No newline at end of file
+
+  @Test
+  public void testCompareTo_whenColorsCreatedWithGrayLevel(){
+    ByteGrayColor color1 = new ByteGrayColor(100);
+    ByteGrayColor color2 = new ByteGrayColor(100);
+    ByteGrayColor color3 = new ByteGrayColor(150);
+    assertThat(color1.compareTo(color3)).isNegative();
+    assertThat(color3.compareTo(color1)).isPositive();
+    assertThat(color1.compareTo(color3)).isEqualTo(-(color3.compareTo(color1)));
+    assertThat(color1.compareTo(color2)).isZero();
+  }
+
+  @Test
+  public void testCompareTo_whenColorsCreatedWithLuminosity(){
+    ByteGrayColor color1 = new ByteGrayColor(0.20);
+    ByteGrayColor color2 = new ByteGrayColor(0.20);
+    ByteGrayColor color3 = new ByteGrayColor(0.60);
+    assertThat(color1.compareTo(color3)).isNegative();
+    assertThat(color3.compareTo(color1)).isPositive();
+    assertThat(color1.compareTo(color3)).isEqualTo(-(color3.compareTo(color1)));
+    assertThat(color1.compareTo(color2)).isZero();
+  }
+
+  @Test
+  public void testCompareTo_whenColorsCreatedWithLuminosityAndGrayLevel(){
+    ByteGrayColor color1 = new ByteGrayColor(0.);
+    ByteGrayColor color2 = new ByteGrayColor(0);
+    ByteGrayColor color3 = new ByteGrayColor(100);
+    assertThat(color1.compareTo(color3)).isNegative();
+    assertThat(color3.compareTo(color1)).isPositive();
+    assertThat(color1.compareTo(color3)).isEqualTo(-(color3.compareTo(color1)));
+    assertThat(color1.compareTo(color2)).isZero();
+  }
+}
diff --git a/src/test/java/MatrixGrayImageTest.java b/src/test/java/MatrixGrayImageTest.java
index 82c2ec9cc84206712d76b500a062384b2ede3c9a..72e61003a07e683217990f7025cddb57a974730d 100644
--- a/src/test/java/MatrixGrayImageTest.java
+++ b/src/test/java/MatrixGrayImageTest.java
@@ -5,16 +5,27 @@ import static org.assertj.core.api.Assertions.*;
 class MatrixGrayImageTest {
 
     @Test
-    void getWidth() {
+    void testGetWidth() {
         assertThat(new MatrixGrayImage(0,0).getWidth()).isEqualTo(0);
         assertThat(new MatrixGrayImage(10,20).getWidth()).isEqualTo(10);
         assertThat(new MatrixGrayImage(400,300).getWidth()).isEqualTo(400);
     }
 
     @Test
-    void getHeight() {
+    void testGetHeight() {
         assertThat(new MatrixGrayImage(0,0).getHeight()).isEqualTo(0);
         assertThat(new MatrixGrayImage(10,20).getHeight()).isEqualTo(20);
         assertThat(new MatrixGrayImage(400,300).getHeight()).isEqualTo(300);
     }
+
+    @Test
+    void testGetPixel_whenPixelHasBeenSet() {
+        GrayColor grey1 = new ByteGrayColor(0.2);
+        GrayColor grey2 = new ByteGrayColor(0.8);
+        MatrixGrayImage image = new MatrixGrayImage(10, 10);
+        image.setPixel(grey1, 1, 1);
+        assertThat(image.getPixelGrayColor(1,1)).isEqualTo(grey1);
+        image.setPixel(grey2, 3, 9);
+        assertThat(image.getPixelGrayColor(3,9)).isEqualTo(grey2);
+    }
 }
\ No newline at end of file