Merge pull request #2 from ChangruHenryQian/branch-A-Assertions

Implement assertions

build.gradle

@@ -55,6 +55,8 @@ shadowJar {
 
 run{
     standardInput = System.in
+
+    enableAssertions = true
 }
 
 mainClassName = "duke.Launcher"

data/tasks.txt

@@ -1,2 +0,0 @@
-T | 1 | daf 
-T | 1 | 2rd

src/main/java/duke/Storage.java

@@ -59,6 +59,7 @@ private File getFile(String path) throws IOException {
      * @throws FileNotFoundException If an attempt to open the file fails.
      */
     private ArrayList<Task> loadTasks(File f) throws FileNotFoundException {
+        assert f.exists();
         Scanner s = new Scanner(f);
         ArrayList<Task> tasks = new ArrayList<>();
         while (s.hasNext()) {

src/main/java/duke/Task.java

@@ -13,11 +13,15 @@ public class Task {
      * @param description Description of the task.
      */
     public Task(String description) {
+        assert !description.isEmpty();
+
         this.description = description;
         this.isDone = false;
     }
 
     public Task(String description, boolean isDone) {
+        assert !description.isEmpty();
+
         this.description = description;
         this.isDone = isDone;
     }

src/main/java/duke/TaskList.java

@@ -47,6 +47,8 @@ public String addTask(Task t) {
      * @return The message for deleting.
      */
     public String deleteTask(int num) {
+        assert num >= 0;
+
         Task re = tasks.remove(num);
         this.storage.rewriteFile(tasks);
         return Ui.deleteTask(re, tasks);
@@ -59,6 +61,8 @@ public String deleteTask(int num) {
      * @return The message for marking.
      */
     public String markTask(int num) {
+        assert num >= 0;
+
         Task t = tasks.get(num);
         t.markAsDone();
         this.storage.rewriteFile(tasks);
@@ -72,6 +76,8 @@ public String markTask(int num) {
      * @return The message for searching results.
      */
     public String findTask(String keyword) {
+        assert keyword != null;
+
         ArrayList<Task> result = new ArrayList<>();
         for (int i = 0; i < this.tasks.size(); i++) {
             if (!tasks.get(i).toString().contains(keyword)) {