diff --git a/tests/check_shebang_scripts_are_executable_test.py b/tests/check_shebang_scripts_are_executable_test.py
new file mode 100644
index 0000000..9e78b06
--- /dev/null
+++ b/tests/check_shebang_scripts_are_executable_test.py
@@ -0,0 +1,87 @@
+import os
+
+import pytest
+
+from pre_commit_hooks.check_shebang_scripts_are_executable import \
+    _check_git_filemode
+from pre_commit_hooks.check_shebang_scripts_are_executable import main
+from pre_commit_hooks.util import cmd_output
+
+
+def test_check_git_filemode_passing(tmpdir):
+    with tmpdir.as_cwd():
+        cmd_output('git', 'init', '.')
+
+        f = tmpdir.join('f')
+        f.write('#!/usr/bin/env bash')
+        f_path = str(f)
+        cmd_output('chmod', '+x', f_path)
+        cmd_output('git', 'add', f_path)
+        cmd_output('git', 'update-index', '--chmod=+x', f_path)
+
+        g = tmpdir.join('g').ensure()
+        g_path = str(g)
+        cmd_output('git', 'add', g_path)
+
+        files = [f_path, g_path]
+        assert _check_git_filemode(files) == 0
+
+        # this is the one we should trigger on
+        h = tmpdir.join('h')
+        h.write('#!/usr/bin/env bash')
+        h_path = str(h)
+        cmd_output('git', 'add', h_path)
+
+        files = [h_path]
+        assert _check_git_filemode(files) == 1
+
+
+def test_check_git_filemode_passing_unusual_characters(tmpdir):
+    with tmpdir.as_cwd():
+        cmd_output('git', 'init', '.')
+
+        f = tmpdir.join('mañana.txt')
+        f.write('#!/usr/bin/env bash')
+        f_path = str(f)
+        cmd_output('chmod', '+x', f_path)
+        cmd_output('git', 'add', f_path)
+        cmd_output('git', 'update-index', '--chmod=+x', f_path)
+
+        files = (f_path,)
+        assert _check_git_filemode(files) == 0
+
+
+def test_check_git_filemode_failing(tmpdir):
+    with tmpdir.as_cwd():
+        cmd_output('git', 'init', '.')
+
+        f = tmpdir.join('f').ensure()
+        f.write('#!/usr/bin/env bash')
+        f_path = str(f)
+        cmd_output('git', 'add', f_path)
+
+        files = (f_path,)
+        assert _check_git_filemode(files) == 1
+
+
+@pytest.mark.parametrize(
+    ('content', 'mode', 'expected'),
+    (
+        pytest.param('#!python', '+x', 0, id='shebang with executable'),
+        pytest.param('#!python', '-x', 1, id='shebang without executable'),
+        pytest.param('', '+x', 0, id='no shebang with executable'),
+        pytest.param('', '-x', 0, id='no shebang without executable'),
+    ),
+)
+def test_git_executable_shebang(temp_git_dir, content, mode, expected):
+    with temp_git_dir.as_cwd():
+        path = temp_git_dir.join('path')
+        path.write(content)
+        cmd_output('git', 'add', str(path))
+        cmd_output('chmod', mode, str(path))
+        cmd_output('git', 'update-index', f'--chmod={mode}', str(path))
+
+        # simulate how identify chooses that something is executable
+        filenames = [path for path in [str(path)] if os.access(path, os.X_OK)]
+
+        assert main(filenames) == expected