Adding initial testing

requirements.txt

@@ -1,2 +1,2 @@
 xlrd >= 1.0.0
-xlwt >= 1.0.0
+xlwt >= 1.0.0

setup.py

@@ -18,7 +18,8 @@
 setup_requirements = [
     'flake8 >= 3.5.0',
     'stringify >= 0.1.1',
-    'sphinx >= 1.6'
+    'sphinx >= 1.6',
+    'pytest >= 3.5'
 ]
 
 # provide correct path for version

test.py

@@ -0,0 +1,36 @@
+import tkinter as tk
+
+import pytest
+
+from tk_tools import *
+
+
+@pytest.fixture
+def create_root():
+    root = tk.Tk()
+    yield root
+
+
+def test_init(create_root):
+    """
+    Ensures that all elements of the GUI may be instantiated
+    without errors.
+    """
+    RotaryScale(create_root)
+    Gauge(create_root)
+    Graph(create_root, 0, 10, 0, 10, 0.1, 0.1)
+    Led(create_root)
+    EntryGrid(create_root, 3)
+    LabelGrid(create_root, 3)
+    ButtonGrid(create_root, 3)
+    KeyValueEntry(create_root, keys=['1', '2'])
+    SmartOptionMenu(create_root, ['1', '2'])
+    SmartSpinBox(create_root)
+    SmartCheckbutton(create_root)
+    Calendar(create_root)
+    MultiSlotFrame(create_root)
+    SevenSegmentDigits(create_root)
+    BinaryLabel(create_root)
+    ToolTip(BinaryLabel(create_root), 'some text')
+
+    assert True