add CLI interface and impl for category

0-Plugin/src/test/java/cli/category/CategoryCommandsTest.java

@@ -0,0 +1,41 @@
+package cli.category;
+
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
+
+import java.util.Set;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.doNothing;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class CategoryCommandsTest {
+
+	CategoryCliAdapter mockAdapter = mock(CategoryCliAdapter.class);
+
+	@Test
+	void addCommandWorks() {
+		var categoryName = "funStuff";
+		ArgumentCaptor<String> valueCapture = ArgumentCaptor.forClass(String.class);
+		doNothing().when(mockAdapter).addCategory(valueCapture.capture());
+		var sut = new CategoryCommands(mockAdapter);
+
+		var returnValue = sut.executeSubcommand(new String[]{"add", categoryName});
+
+		assertEquals(categoryName, valueCapture.getValue());
+		assertEquals("Added the new category", returnValue);
+	}
+
+	@Test
+	void getCommandWorks() {
+		var sut = new CategoryCommands(mockAdapter);
+		when(mockAdapter.getCategories()).thenReturn(Set.of("funStuff", "workStuff"));
+		var returnValue = sut.executeSubcommand(new String[]{"get"});
+
+		var expected =
+				"Available Categories:" + System.lineSeparator() + "funStuff" + System.lineSeparator() + "workStuff";
+
+		assertEquals(expected, returnValue);
+	}
+}