created method getAverageGpaForPartTimeStudents + language tests

app/src/main/java/com/example/paktalin/agilejava/Session.java

@@ -42,6 +42,19 @@ public abstract class Session implements Comparable<Session>{
         student.addCredits(numberOfCredits);
     }
 
+    double getAverageGpaForPartTimeStudents() {
+        double total = 0;
+        int counter = 0;
+        for (Student student : getAllStudents())
+            if (!student.isFullTime()) {
+                counter++;
+                total += student.getGpa();
+            }
+        return total / counter;
+    }
+
+    protected abstract int getSessionLength();
+
     Date getEndDate() {
         GregorianCalendar calendar = new GregorianCalendar();
         calendar.setTime(getStartDate());
@@ -59,22 +72,23 @@ public abstract class Session implements Comparable<Session>{
         return students;
     }
 
-    protected abstract int getSessionLength();
-
     Date getStartDate() {
         return startDate;
     }
+
     int getNumberOfStudents() {
         return students.size();
     }
+
     String getDepartment() {
         return department;
     }
+
     String getNumber() {
         return number;
     }
+
     Student get(int index) {
         return students.get(index);
     }
-
 }

app/src/test/java/com/example/paktalin/agilejava/SessionTest.java

@@ -65,4 +65,30 @@ abstract public class SessionTest extends TestCase {
         Session session = createSession("ENGL", "200", startDate);
         assertEquals(getExpectedEndDate(), session.getEndDate());
     }
+
+    public void testAverageGpaForPartTimeStudents() {
+        session.enroll(createFullTimeStudent());
+        assertEquals(1, session.getNumberOfStudents());
+
+        createPartTimer("1", Student.Grade.A);
+        assertEquals(2, session.getNumberOfStudents());
+        createPartTimer("2", Student.Grade.D);
+        assertEquals(3, session.getNumberOfStudents());
+
+        assertEquals(2.5, session.getAverageGpaForPartTimeStudents(), 0.05);
+    }
+
+    private void createPartTimer(String name, Student.Grade grade) {
+        Student partTimer = new Student(name);
+        partTimer.addGrade(grade);
+        session.enroll(partTimer);
+        assertFalse(partTimer.isFullTime());
+        assertEquals(grade.getPoints(), partTimer.getGpa(), 0.05);
+    }
+
+    private Student createFullTimeStudent() {
+        Student student = new Student("a");
+        student.addCredits(Student.CREDITS_REQUIRED_FOR_FULL_TIME);
+        return student;
+    }
 }

app/src/test/java/com/example/paktalin/agilejava/language_tests/LoopTest.java

@@ -31,13 +31,50 @@ public class LoopTest extends TestCase {
         assertFalse(isPalindrome("abbaa"));
     }
 
+    public void testFibonacci() {
+        assertEquals(0, fib(0));
+        assertEquals(1, fib(1));
+        assertEquals(1, fib(2));
+        assertEquals(2, fib(3));
+        assertEquals(3, fib(4));
+        assertEquals(5, fib(5));
+    }
+
     private boolean isPalindrome(String string){
+        int limit = string.length() / 2;
         for
                 (int forward = 0, backward = string.length() - 1;
-                forward < string.length();
+                forward < limit;
                 forward++, backward--)
             if (string.charAt(forward) != string.charAt(backward))
                 return false;
         return true;
     }
+
+    private int fib(int x) {
+        if (x == 0)
+            return 0;
+        if (x == 1)
+            return 1;
+        return fib(x - 1) + fib(x - 2);
+    }
+
+    public void testEndTrim() {
+        assertEquals("", endTrim(""));
+        assertEquals("  x", endTrim("  x  "));
+        assertEquals("y", endTrim("y"));
+        assertEquals("xaxa", endTrim("xaxa"));
+        assertEquals("", endTrim(" "));
+        assertEquals("xxx", endTrim("xxx       "));
+    }
+
+    private String endTrim(String source) {
+        int i = source.length() - 1;
+        while (i >= 0) {
+            if (source.charAt(i) != ' ')
+                break;
+            i--;
+        }
+        return source.substring(0, i + 1);
+    }
 }