diff --git a/shell_command/tests/__init__.py b/shell_command/tests/__init__.py
index e69de29..d025db1 100644
--- a/shell_command/tests/__init__.py
+++ b/shell_command/tests/__init__.py
@@ -0,0 +1,89 @@
+import unittest
+
+from shell_command import ShellCommand
+
+
+class ShellCommandSharedTestCase(unittest.TestCase):
+    """Shared tests for ShellCommand and its subclasses."""
+
+    def setUp(self):
+        """Set up for test."""
+        # Make sure the input and output options are explicitly set to
+        # [] otherwise they hang around from previous tests.
+        self.command = ShellCommand(input_options=[], output_options=[])
+        self.expected_executable = ""
+        self.expected_base_options = []
+        self.expected_input_options = []
+        self.expected_filter_options = []
+        self.expected_output_options = []
+
+    def tearDown(self):
+        """Clean up after test."""
+        self.command = None
+
+    def test_base_options(self):
+        """Test that base options match expected."""
+        self.assertEqual(
+            self.command._base_options, self.expected_base_options)
+    
+    def test_input_options(self):
+        """Test that input options match expected."""
+        self.assertEqual(
+            self.command.input_options, self.expected_input_options)
+    
+    def test_output_options(self):
+        """Test that output options match expected."""
+        self.assertEqual(
+            self.command.output_options, self.expected_output_options)
+    
+    def test_executable_string(self):
+        """Test that executable path matches expected."""
+        with self.subTest(msg="unquoted paths match"):
+            self.assertEqual(
+                self.command.executable_string(quote=False),
+                self.expected_executable)
+        with self.subTest(msg="unquoted paths match"):
+            # Note: don't explicitly specify quoted value, because
+            # the executable path will vary across different systems.
+            self.assertEqual(
+                self.command.executable_string(quote=True),
+                ShellCommand.shellquote(self.expected_executable))
+
+    def test_argument_string(self):
+        """Test that argument string matches expected."""
+        args = (self.expected_base_options + self.expected_input_options +
+            self.expected_filter_options + self.expected_output_options)
+        with self.subTest(msg="unquoted agruments match"):
+            self.assertEqual(
+                self.command.argument_string(quote=False), " ".join(args))
+        with self.subTest(msg="quoted agruments match"):
+            self.assertEqual(
+                self.command.argument_string(quote=True),
+                " ".join([ShellCommand.shellquote(a) for a in args]))
+
+    def test_argument_list(self):
+        """Test that argument list matches expected."""
+        self.assertEqual(self.command.argument_list(),
+            self.expected_base_options + self.expected_input_options +
+            self.expected_filter_options + self.expected_output_options)
+
+    def test_command_string(self):
+        """Test that command string matches expected."""
+        args = (self.expected_base_options + self.expected_input_options +
+            self.expected_filter_options + self.expected_output_options)
+        expected_cmd_unquoted = (
+            "{exe} {arg}".format(exe=self.expected_executable,
+                arg=" ".join(args))
+        )
+        expected_cmd_quoted = (
+            '{exe} {arg}'.format(
+                exe=ShellCommand.shellquote(self.expected_executable),
+                arg=" ".join([ShellCommand.shellquote(a) for a in args]))
+        )
+        with self.subTest(msg="unquoted command string matches"):
+            self.assertEqual(
+                self.command.command_string(quote=False),
+                expected_cmd_unquoted)
+        with self.subTest(msg="quoted command string matches"):
+            self.assertEqual(
+                self.command.command_string(quote=True), expected_cmd_quoted)