diff --git a/tests/ftguess/__init__.py b/tests/ftguess/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/tests/ftguess/__init__.py
diff --git a/tests/ftguess/test_basic.py b/tests/ftguess/test_basic.py
new file mode 100644
index 0000000..6308c9b
--- /dev/null
+++ b/tests/ftguess/test_basic.py
@@ -0,0 +1,97 @@
+"""Test ftguess"""
+
+import unittest
+import os
+from os.path import splitext
+from oletools import ftguess
+
+# Directory with test data, independent of current working directory
+from tests.test_utils import DATA_BASE_DIR
+from tests.test_utils.testdata_reader import loop_over_files
+
+
+class TestFTGuess(unittest.TestCase):
+    """Test ftguess"""
+
+    def test_all(self):
+        """Run all files in test-data and compare to known ouput"""
+        # ftguess knows extension for each FType, create a reverse mapping
+        used_types = (
+            ftguess.FType_RTF, ftguess.FType_Generic_OLE,
+            ftguess.FType_Generic_Zip, ftguess.FType_Word97,
+            ftguess.FType_Word2007, ftguess.FType_Word2007_Macro,
+            ftguess.FType_Word2007_Template,
+            ftguess.FType_Word2007_Template_Macro, ftguess.FType_Excel97,
+            ftguess.FType_Excel2007,
+            ftguess.FType_Excel2007_XLSX , ftguess.FType_Excel2007_XLSM ,
+            ftguess.FType_Excel2007_Template,
+            ftguess.FType_Excel2007_Template_Macro,
+            ftguess.FType_Excel2007_Addin_Macro, ftguess.FType_Powerpoint97,
+            ftguess.FType_Powerpoint2007_Presentation,
+            ftguess.FType_Powerpoint2007_Slideshow,
+            ftguess.FType_Powerpoint2007_Macro,
+            ftguess.FType_Powerpoint2007_Slideshow_Macro,
+            ftguess.FType_XPS,
+        )
+        ftype_for_extension = dict()
+        for ftype in used_types:
+            for extension in ftype.extensions:
+                ftype_for_extension[extension] = ftype
+
+        # TODO: xlsb is not implemented yet
+        ftype_for_extension['xlsb'] = ftguess.FType_Generic_OpenXML
+
+        for filename, file_contents in loop_over_files():
+            # let the system guess
+            guess = ftguess.ftype_guess(data=file_contents)
+            #print(f'for debugging: {filename} --> {guess}')
+
+            # determine what we expect...
+            before_dot, extension = splitext(filename)
+            if extension == '.zip':
+                extension = splitext(before_dot)[1]
+            elif filename in ('basic/empty', 'basic/text'):
+                extension = '.csv'    # have just like that
+            elif not extension:
+                self.fail('Could not find extension for test sample {0}'
+                          .format(filename))
+            extension = extension[1:]      # remove the leading '.'
+
+            # encrypted files are mostly recognized (yet?), except .xls
+            if filename.startswith('encrypted/'):
+                if extension == 'xls':
+                    expect = ftguess.FType_Excel97
+                else:
+                    expect = ftguess.FType_Generic_OLE
+
+            elif extension in ('xml', 'csv', 'odt', 'ods', 'odp', 'potx', 'potm'):
+                # not really an office file type
+                expect = ftguess.FType_Unknown
+
+            elif filename == 'basic/encrypted.docx':
+                expect = ftguess.FType_Generic_OLE
+
+            else:
+                # other files behave nicely, so extension determines the type
+                expect = ftype_for_extension[extension]
+
+                self.assertEqual(guess.container, expect.container,
+                                 msg='ftguess guessed container {0} for {1} '
+                                     'but we expected {2}'
+                                     .format(guess.container, filename,
+                                             expect.container))
+                self.assertEqual(guess.filetype, expect.filetype,
+                                 msg='ftguess guessed filetype {0} for {1} '
+                                     'but we expected {2}'
+                                     .format(guess.filetype, filename,
+                                             expect.filetype))
+                self.assertEqual(guess.application, expect.application,
+                                 msg='ftguess guessed application {0} for {1} '
+                                     'but we expected {2}'
+                                     .format(guess.application, filename,
+                                             expect.application))
+
+
+# just in case somebody calls this file as a script
+if __name__ == '__main__':
+    unittest.main()