Add Faculty class

Add Faculty and its test class.

src/main/java/staffconnect/model/person/Faculty.java

@@ -0,0 +1,47 @@
+package staffconnect.model.person;
+
+import static java.util.Objects.requireNonNull;
+import static staffconnect.commons.util.AppUtil.checkArgument;
+
+public class Faculty {
+    public static final String MESSAGE_CONSTRAINTS = "This can be any non-blank String content.";
+    /*
+     * The first character of the faculty must not be a whitespace,
+     * otherwise " " (a blank string) becomes a valid input.
+     */
+    public static final String VALIDATION_REGEX = "[^\\s].*";
+    private final String value;
+
+    /**
+     * Constructs a {@code Faculty}.
+     *
+     * @param faculty A valid faculty.
+     */
+    public Faculty(String faculty) {
+        requireNonNull(faculty);
+        checkArgument(isValidFaculty(faculty), MESSAGE_CONSTRAINTS);
+        value = faculty;
+    }
+
+    public static boolean isValidFaculty(String test) {
+        return test.matches(VALIDATION_REGEX);
+    }
+
+    @Override
+    public String toString() {
+        return value;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj instanceof Faculty) {
+            return ((Faculty) obj).value.equals(this.value);
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return value.hashCode();
+    }
+}

src/test/java/staffconnect/model/person/FacultyTest.java

@@ -0,0 +1,57 @@
+package staffconnect.model.person;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static staffconnect.testutil.Assert.assertThrows;
+
+public class FacultyTest {
+    @Test
+    public void constructor_null_throwsNullPointerException() {
+        assertThrows(NullPointerException.class, () -> new Faculty(null));
+    }
+
+    @Test
+    public void constructor_invalidFaculty_throwsIllegalArgumentException() {
+        String invalidFaculty = "";
+        assertThrows(IllegalArgumentException.class, () -> new Faculty(invalidFaculty));
+    }
+
+    @Test
+    public void isValidFaculty() {
+        // null Faculty
+        assertThrows(NullPointerException.class, () -> Faculty.isValidFaculty(null));
+
+        // invalid faculties
+        assertFalse(Faculty.isValidFaculty("")); // empty string
+        assertFalse(Faculty.isValidFaculty(" ")); // spaces only
+
+        // valid Faculties
+        assertTrue(Faculty.isValidFaculty("~"));// one character
+        assertTrue(Faculty.isValidFaculty("School of Computing"));// long faculty
+        assertTrue(Faculty.isValidFaculty("abcdefg"));
+    }
+
+    @Test
+    public void equals() {
+        Faculty faculty = new Faculty("a faculty");
+
+        // same values -> returns true
+        assertEquals(faculty, new Faculty("a faculty"));
+
+        // same object -> returns true
+        assertEquals(faculty, faculty);
+
+        // null -> returns false
+        assertNotEquals(null, faculty);
+
+        // different types -> returns false
+        assertFalse(faculty.equals(5.0f));
+
+        // different values -> returns false
+        assertNotEquals(faculty, new Faculty("Other Faculty"));
+    }
+}