add some Espresso tests and a cheat sheet pdf

app/src/androidTest/java/calculator/simplemobiletools/com/simple_calculator/MainActivityTest.java

@@ -9,19 +9,182 @@ import org.junit.runner.RunWith;
 
 import static android.support.test.espresso.Espresso.onView;
 import static android.support.test.espresso.action.ViewActions.click;
+import static android.support.test.espresso.action.ViewActions.longClick;
 import static android.support.test.espresso.assertion.ViewAssertions.matches;
 import static android.support.test.espresso.matcher.ViewMatchers.withId;
 import static android.support.test.espresso.matcher.ViewMatchers.withText;
 
 @RunWith(AndroidJUnit4.class)
 public class MainActivityTest {
-    @Rule
-    public ActivityTestRule<MainActivity> mActivityRule =
-            new ActivityTestRule<>(MainActivity.class);
+    @Rule public final ActivityTestRule<MainActivity> activity = new ActivityTestRule<>(MainActivity.class);
 
     @Test
-    public void addDigitTest() {
-        onView(withId(R.id.btn_5)).perform(click());
-        onView(withId(R.id.result)).check(matches(withText("5")));
+    public void addSimpleDigit() {
+        press(R.id.btn_5);
+        checkResult("5");
+    }
+
+    @Test
+    public void removeLeadingZero() {
+        press(R.id.btn_0);
+        press(R.id.btn_5);
+        checkResult("5");
+    }
+
+    @Test
+    public void additionTest() {
+        press(R.id.btn_minus);
+        press(R.id.btn_2);
+        press(R.id.btn_decimal);
+        press(R.id.btn_5);
+        press(R.id.btn_plus);
+        press(R.id.btn_6);
+        press(R.id.btn_equals);
+        checkResult("3.5");
+        press(R.id.btn_equals);
+        checkResult("9.5");
+    }
+
+    @Test
+    public void subtractionTest() {
+        press(R.id.btn_7);
+        press(R.id.btn_decimal);
+        press(R.id.btn_8);
+        press(R.id.btn_minus);
+        press(R.id.btn_3);
+        press(R.id.btn_equals);
+        checkResult("4.8");
+    }
+
+    @Test
+    public void multiplyTest() {
+        press(R.id.btn_2);
+        press(R.id.btn_multiply);
+        press(R.id.btn_4);
+        press(R.id.btn_equals);
+        checkResult("8");
+    }
+
+    @Test
+    public void divisionTest() {
+        press(R.id.btn_1);
+        press(R.id.btn_0);
+        press(R.id.btn_divide);
+        press(R.id.btn_4);
+        press(R.id.btn_equals);
+        checkResult("2.5");
+    }
+
+    @Test
+    public void divisionbyZeroTest() {
+        press(R.id.btn_8);
+        press(R.id.btn_divide);
+        press(R.id.btn_0);
+        press(R.id.btn_equals);
+        checkResult("0");
+    }
+
+    @Test
+    public void moduloTest() {
+        press(R.id.btn_7);
+        press(R.id.btn_modulo);
+        press(R.id.btn_2);
+        press(R.id.btn_equals);
+        checkResult("1");
+    }
+
+    @Test
+    public void powerTest() {
+        press(R.id.btn_2);
+        press(R.id.btn_power);
+        press(R.id.btn_3);
+        press(R.id.btn_equals);
+        checkResult("8");
+    }
+
+    @Test
+    public void rootTest() {
+        press(R.id.btn_9);
+        press(R.id.btn_root);
+        checkResult("3");
+    }
+
+    @Test
+    public void clearTest() {
+        press(R.id.btn_2);
+        press(R.id.btn_5);
+        press(R.id.btn_decimal);
+        press(R.id.btn_7);
+        press(R.id.btn_clear);
+        checkResult("25.");
+        press(R.id.btn_clear);
+        checkResult("25");
+        press(R.id.btn_clear);
+        checkResult("2");
+        press(R.id.btn_clear);
+        checkResult("0");
+    }
+
+    @Test
+    public void clearLongTest() {
+        press(R.id.btn_2);
+        press(R.id.btn_plus);
+        press(R.id.btn_5);
+        press(R.id.btn_equals);
+        longPress((R.id.btn_clear));
+        press(R.id.btn_plus);
+        press(R.id.btn_2);
+        press(R.id.btn_equals);
+        checkResult("2");
+    }
+
+    @Test
+    public void complexTest() {
+        press(R.id.btn_2);
+        press(R.id.btn_plus);
+        press(R.id.btn_5);
+        press(R.id.btn_minus);
+        checkResult("7");
+
+        press(R.id.btn_3);
+        press(R.id.btn_multiply);
+        checkResult("4");
+
+        press(R.id.btn_5);
+        press(R.id.btn_divide);
+        checkResult("20");
+
+        press(R.id.btn_2);
+        press(R.id.btn_modulo);
+        checkResult("10");
+
+        press(R.id.btn_4);
+        press(R.id.btn_power);
+        checkResult("2");
+
+        press(R.id.btn_8);
+        press(R.id.btn_modulo);
+        checkResult("256");
+
+        press(R.id.btn_root);
+        checkResult("16");
+
+        press(R.id.btn_clear);
+        checkResult("1");
+
+        press(R.id.btn_clear);
+        checkResult("0");
+    }
+
+    private void press(int id) {
+        onView(withId(id)).perform(click());
+    }
+
+    private void longPress(int id) {
+        onView(withId(id)).perform(longClick());
+    }
+
+    private void checkResult(String desired) {
+        onView(withId(R.id.result)).check(matches(withText(desired)));
     }
 }