Sarthak | Refactors Arguments, it does not inherit from ArrayList<String>

Author: SarthakMakhija

src/main/java/com/codurance/training/commands/Arguments.java

@@ -1,20 +1,12 @@
 package com.codurance.training.commands;
 
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Collectors;
 
-/**
- * The class `Arguments` is showing signs of both mutability and immutability.
- * Signs of mutability:
- *  - Arguments extends from ArrayList<String> which is mutable.
- *  - The method `skipOne` creates a new instance of Arguments, which means the author does not want to change the existing collection.
- *  An instance of Arguments is passed to all the Commands. Given, Arguments extends from ArrayList<String>, it gives all the commands
- *  the authority to mutate arguments.
- *  Technically, Arguments should never be mutated once created.
- */
-public class Arguments extends ArrayList<String> {
+public class Arguments {
+
+    private final List<String> arguments;
 
     static Arguments skipOneAndCreate(String[] parts) {
         if (parts == null) {
@@ -24,26 +16,26 @@ static Arguments skipOneAndCreate(String[] parts) {
     }
 
     Arguments(List<String> arguments) {
-        this.addAll(arguments);
+        this.arguments = arguments;
     }
 
     Arguments skipOne() {
-        return new Arguments(this.subList(1, this.size()));
+        return new Arguments(this.arguments.subList(1, this.count()));
     }
 
     int argumentAtIndexAsInt(int index) {
-        return Integer.parseInt(this.get(index));
+        return Integer.parseInt(this.arguments.get(index));
     }
 
     String argumentAtIndexAsString(int index) {
-        return get(index);
+        return this.arguments.get(index);
     }
 
     int count() {
-        return size();
+        return this.arguments.size();
     }
 
-    boolean hasAny() {
-        return size() == 0;
+    boolean isEmpty() {
+        return this.arguments.isEmpty();
     }
 }

src/main/java/com/codurance/training/commands/ShowCommand.java

@@ -15,7 +15,7 @@ class ShowCommand implements Command {
 
     @Override
     public void execute(Arguments arguments) throws Exception {
-        assert (arguments.hasAny());
+        assert (arguments.isEmpty());
         this.writer.write(this.projects.format());
     }
 }

src/test/java/com/codurance/training/commands/ArgumentsTest.java

@@ -4,32 +4,35 @@
 
 import java.util.List;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 public class ArgumentsTest {
 
     @Test
     public void skipOneAndCreateArguments() {
         Arguments arguments = Arguments.skipOneAndCreate(new String[]{"an", "argument", "1"});
-        assertEquals(List.of("argument", "1"), arguments);
+        assertEquals("argument", arguments.argumentAtIndexAsString(0));
+        assertEquals("1", arguments.argumentAtIndexAsString(1));
     }
 
     @Test
     public void skipOneAndCreateEmptyArguments() {
         Arguments arguments = Arguments.skipOneAndCreate(new String[]{});
-        assertEquals(List.of(), arguments);
+        assertTrue(arguments.isEmpty());
     }
 
     @Test
     public void skipOneAndCreateEmptyArgumentsGivenNull() {
         Arguments arguments = Arguments.skipOneAndCreate(null);
-        assertEquals(List.of(), arguments);
+        assertTrue(arguments.isEmpty());
     }
 
     @Test
     public void skipOneFromArguments() {
         Arguments arguments = new Arguments(List.of("an", "argument", "1"));
-        assertEquals(List.of("argument", "1"), arguments.skipOne());
+        Arguments skipped = arguments.skipOne();
+        assertEquals("argument", skipped.argumentAtIndexAsString(0));
+        assertEquals("1", skipped.argumentAtIndexAsString(1));
     }
 
     @Test
@@ -43,4 +46,40 @@ public void argumentAtIndex1AsInt() {
         Arguments arguments = new Arguments(List.of("0", "200", "1"));
         assertEquals(200, arguments.argumentAtIndexAsInt(1));
     }
+
+    @Test
+    public void argumentAtIndex0AsString() {
+        Arguments arguments = new Arguments(List.of("1", "argument", "1"));
+        assertEquals("1", arguments.argumentAtIndexAsString(0));
+    }
+
+    @Test
+    public void argumentAtIndex1AsString() {
+        Arguments arguments = new Arguments(List.of("0", "200", "1"));
+        assertEquals("200", arguments.argumentAtIndexAsString(1));
+    }
+
+    @Test
+    public void zeroArguments() {
+        Arguments arguments = new Arguments(List.of());
+        assertEquals(0, arguments.count());
+    }
+
+    @Test
+    public void threeArguments() {
+        Arguments arguments = new Arguments(List.of("0", "200", "1"));
+        assertEquals(3, arguments.count());
+    }
+
+    @Test
+    public void argumentsIsEmpty() {
+        Arguments arguments = Arguments.skipOneAndCreate(null);
+        assertTrue(arguments.isEmpty());
+    }
+
+    @Test
+    public void argumentsIsNotEmpty() {
+        Arguments arguments = new Arguments(List.of("argument"));
+        assertFalse(arguments.isEmpty());
+    }
 }

src/test/java/com/codurance/training/commands/CommandLineTest.java

@@ -22,7 +22,7 @@ public void parseCheckCommand() {
         CommandDescription commandDescription = commandLine.parse();
 
         assertEquals(CommandType.CHECK, commandDescription.commandType());
-        assertEquals(List.of("100"), commandDescription.arguments());
+        assertEquals("100", commandDescription.arguments().argumentAtIndexAsString(0));
     }
 
     @Test
@@ -31,7 +31,7 @@ public void parseUncheckCommand() {
         CommandDescription commandDescription = commandLine.parse();
 
         assertEquals(CommandType.UNCHECK, commandDescription.commandType());
-        assertEquals(List.of("100"), commandDescription.arguments());
+        assertEquals("100", commandDescription.arguments().argumentAtIndexAsString(0));
     }
 
     @Test
@@ -40,7 +40,8 @@ public void parseAddProjectCommand() {
         CommandDescription commandDescription = commandLine.parse();
 
         assertEquals(CommandType.ADD, commandDescription.commandType());
-        assertEquals(List.of("project", "caizin"), commandDescription.arguments());
+        assertEquals("project", commandDescription.arguments().argumentAtIndexAsString(0));
+        assertEquals("caizin", commandDescription.arguments().argumentAtIndexAsString(1));
     }
 
     @Test
@@ -49,6 +50,8 @@ public void parseAddTaskCommand() {
         CommandDescription commandDescription = commandLine.parse();
 
         assertEquals(CommandType.ADD, commandDescription.commandType());
-        assertEquals(List.of("task", "caizin", "200"), commandDescription.arguments());
+        assertEquals("task", commandDescription.arguments().argumentAtIndexAsString(0));
+        assertEquals("caizin", commandDescription.arguments().argumentAtIndexAsString(1));
+        assertEquals("200", commandDescription.arguments().argumentAtIndexAsString(2));
     }
 }