I have added changes

AliceAndBobEngine.java

@@ -6,42 +6,64 @@
 public class AliceAndBobEngine {
     /**
      * return `true` if the input value is "Alice"
+     *
      * @param input - this value is variable: it has the potential to be many things
-     * @return `true` if `input` is "Alice"
+     * @return
      */
     public Boolean isAlice(String input) {
-        return null;
+        if (input == "Alice") {
+            return true;
+        }
+        return false;
     }
 
     /**
      * return `true` if the input value is "Bob"
+     *
      * @param input - this value is variable: it has the potential to be many things
      * @return `true` if `input` is "Bob"
      */
     public Boolean isBob(String input) {
-        return null;
+        if (input == "Bob") {
+            return true;
+        }
+        return false;
     }
 
     /**
      * return `true` if the input value is "Alice" or "Bob"
+     *
      * @param input - this value is variable: it has the potential to be many things
      * @return `true` if `input` is "Alice" or "Bob"
      */
     public Boolean isAliceOrBob(String input) {
-        return null;
+        if (input == "Alice") {
+            return true;
+        }
+        if (input == "Bob") {
+            return true;
+        }
+        return false;
     }
 
     /**
      * if the input value is "Alice" or "Bob", then
-     *      return "Hello PERSONSNAME!",
+     * return "Hello PERSONSNAME!",
      * otherwise
-     *      return "Begone, PERSONNAME! You're a stranger!",
+     * return "Begone, PERSONNAME! You're a stranger!",
      * where `PERSONNAME` is replaced with the person's name respectively.
      *
      * @param input - this value is variable: it has the potential to be many things
      * @return respective String value
      */
     public String getGreeting(String input) {
-        return null;
+        if (input == "Alice" || input == "Bob") {
+            return "Hello, " + input + "!";
+        }
+        else { return "Begone, " + input + "! You're a stranger!";
+
+        }
+
+
     }
-}
+} // last one

GetGreetingTest.java

@@ -16,7 +16,7 @@ private void testGetGreeting(String input, String expected) {
         String actual = evaluator.getGreeting(input);
 
         // then
-        Assert.assertEquals(expected, actual);
+        Assert.assertEquals(actual, expected);
     }
 
     @Test
@@ -36,7 +36,7 @@ public void testGetGreetingBob() {
     @Test
     public void testGetGreetingStranger() {
         String[] strangerNames = "Leon Dolio Kris Nobles Desa Lossie Nancy".split(" ");
-        for(String strangerName : strangerNames) {
+        for (String strangerName : strangerNames) {
             String expected = "Begone, " + strangerName + "! You're a stranger!";
             testGetGreeting(strangerName, expected);
         }

IsAliceTest.java

@@ -27,9 +27,8 @@ public void testIsAliceTrue() {
 
     @Test
     public void testIsAliceFalse() {
-        for(String word : "The Quick Brown Fox Jumps Over The Lazy Dog".split(" ")) {
-            testIsAlice(word, false);
-        }
+        for(String word : "The Quick Brown Fox Jumps Over The Lazy Dog".split(" "))
+        { testIsAlice(word, false);}
     }
 
 }