diff --git a/src/main/java/fr/nancy/iut/CalcEngine.java b/src/main/java/fr/nancy/iut/CalcEngine.java
index 5256ea0e74440f72acd0ae2baaaf1f2ac539337a..09d9ef953a3738f96b37cd5464c41d8da33b4c77 100755
--- a/src/main/java/fr/nancy/iut/CalcEngine.java
+++ b/src/main/java/fr/nancy/iut/CalcEngine.java
@@ -72,7 +72,7 @@ public class CalcEngine
         if (previousOperator == '+') {
             displayValue = leftOperand + displayValue;
         }
-        else if(previousOperator == '+'){
+        else if(previousOperator == '-'){
             displayValue = leftOperand - displayValue;
         }
         leftOperand = 0;
@@ -131,4 +131,20 @@ public class CalcEngine
             leftOperand = displayValue;
         }
     }
+
+    /**
+     * getter operator
+     * @return string operator
+     */
+    public char getPreviousOperator() {
+        return previousOperator;
+    }
+
+    /**
+     * getter left operator
+     * @return int
+     */
+    public int getLeftOperand() {
+        return leftOperand;
+    }
 }
diff --git a/src/main/java/fr/nancy/iut/CalcEngineTester.java b/src/main/java/fr/nancy/iut/CalcEngineTester.java
deleted file mode 100755
index dc31dd95a93608f8a4607d855560754034274ac0..0000000000000000000000000000000000000000
--- a/src/main/java/fr/nancy/iut/CalcEngineTester.java
+++ /dev/null
@@ -1,74 +0,0 @@
-package fr.nancy.iut;
-
-/**
- * Test the CalcEngine class.
- * 
- * @author Hacker T. Largebrain 
- * @version 1.0
- */
-// package calculator;
-
-public class CalcEngineTester
-{
-    // The engine to be tested.
-    private CalcEngine engine;
-
-    /**
-     * Constructor for objects of class CalcEngineTester
-     */
-    public CalcEngineTester()
-    {
-        engine = new CalcEngine();
-    }
-    
-    /**
-     * Test everything.
-     */
-    public void testAll()
-    {
-        System.out.println("Testing the addition operation.");
-        System.out.println("The result is: " + testPlus());
-        System.out.println("Testing the subtraction operation.");
-        System.out.println("The result is: " + testMinus());
-        System.out.println("All tests passed.");
-    }
-
-    /**
-     * Test the plus operation of the engine.
-     * @return the result of calculating 3+4.
-     */
-    public int testPlus()
-    {
-        // Make sure the engine is in a valid starting state.
-        engine.clear();
-        // Simulate the key presses: 3 + 4 =
-        engine.numberPressed(3);
-        engine.plus();
-        engine.numberPressed(4);
-        engine.equals();
-        // Return the result, which should be 7.
-        return engine.getDisplayValue();
-    }
-
-    /**
-     * Test the minus operation of the engine.
-     * @return the result of calculating 9 - 4.
-     */
-    public int testMinus()
-    {
-        // Make sure the engine is in a valid starting state.
-        engine.clear();
-        // Simulate the presses: 9 - 4 =
-        engine.numberPressed(9);
-        engine.minus();
-        engine.numberPressed(4);
-        engine.equals();
-        // Return the result, which should be 5.
-        return engine.getDisplayValue();
-    }
-
-    public static void main(String[] args) {
-        CalcEngineTester tester =  new CalcEngineTester();
-        tester.testAll();
-    }
-}
diff --git a/src/test/java/fr/nancy/iut/CalcEngineTest.java b/src/test/java/fr/nancy/iut/CalcEngineTest.java
index 48b2816b08089a4c0e843e4d71df4ab94278bb99..6cd059e729bf96b74ec61a6733dde1a7b0082ad7 100644
--- a/src/test/java/fr/nancy/iut/CalcEngineTest.java
+++ b/src/test/java/fr/nancy/iut/CalcEngineTest.java
@@ -17,10 +17,10 @@ public class CalcEngineTest {
      * @return the number pressed.
      */
 
-    private CalcEngine calculette = new CalcEngine();
 
     @Test
     public void testClear() {
+        CalcEngine calculette = new CalcEngine();
         // Je crée une nouvelle calculatrice
         // CalcEngine calculette = new CalcEngine();
         // Je lui donne une valeur et je vérifie que la valeur en sortie est bien celle que je lui ai donnée
@@ -153,5 +153,35 @@ public class CalcEngineTest {
         assertEquals(8, calculette.getDisplayValue());
     }
 
+    @Test
+    public void testOperandPlus() {
+        CalcEngine calcEngine = new CalcEngine();
+        calcEngine.numberPressed(7);
+        calcEngine.plus();
+        calcEngine.numberPressed(3);
+        String res = String.valueOf(calcEngine.getPreviousOperator());
+        assertEquals(0, res.compareTo("+"));
+        assertEquals(7, calcEngine.getLeftOperand());
+        calcEngine.equals();
+        assertEquals(10, calcEngine.getDisplayValue());
+        assertEquals(0, calcEngine.getLeftOperand());
+    }
+
+    @Test
+    public void testOperandMinus() {
+        CalcEngine calcEngine = new CalcEngine();
+        calcEngine.numberPressed(7);
+        calcEngine.minus();
+        calcEngine.numberPressed(3);
+        String res = String.valueOf(calcEngine.getPreviousOperator());
+        assertEquals(0, res.compareTo("-"));
+        assertEquals(7, calcEngine.getLeftOperand());
+        calcEngine.equals();
+        assertEquals(4, calcEngine.getDisplayValue());
+        assertEquals(0, calcEngine.getLeftOperand());
+    }
+
+
+
 
 }
\ No newline at end of file