diff --git a/tests/test_invoice_template.py b/tests/test_invoice_template.py
index 41fbddef..6900fe51 100644
--- a/tests/test_invoice_template.py
+++ b/tests/test_invoice_template.py
@@ -1,4 +1,4 @@
-
+import unittest
 from invoice2data.extract.invoice_template import InvoiceTemplate
 
 
@@ -14,13 +14,10 @@ def test_template_with_exclude_keyword_is_not_matched():
         ]
     )
     template_matched = InvoiceTemplate.matches_input(InvoiceTempl, optimized_str)
-    assert (
-        template_matched is False
-    ), "A template with exclude keywords is not matched"
+    assert template_matched is False, "A template with exclude keywords is not matched"
 
 
 def test_skip_template_with_too_long_lang_code():
-
     OPTIONS_TEST = {
         "currency": "EUR",
         "date_formats": [],
@@ -37,9 +34,113 @@ def test_skip_template_with_too_long_lang_code():
     try:
         InvoiceTempl = InvoiceTemplate(tpl)
     except Exception:
-        assert True, "Template with language code length != 2 characters is not initiated"
+        assert (
+            True
+        ), "Template with language code length != 2 characters is not initiated"
     else:
         print("InvoiceTempl is\n%s" % InvoiceTempl)
         debug = InvoiceTempl["options"]
         print("debug is\n%s" % debug)
         assert False, "Template class initiated with language code length other then 2"
+
+
+class TestInvoiceTemplateMethods(unittest.TestCase):
+    def test_replace_a_with_b(self):
+        OPTIONS_TEST = {
+            "currency": "EUR",
+            "date_formats": [],
+            "languages": ["aa"],
+            "decimal_separator": ".",
+            "replace": [["a", "b"]],
+        }
+
+        tpl = {}
+        tpl["keywords"] = ["Basic Test"]
+        tpl["exclude_keywords"] = []
+        tpl["options"] = OPTIONS_TEST
+        tpl["template_name"] = "replace_a_with_b"
+        InvoiceTempl = InvoiceTemplate(tpl)
+        extracted_str = "a"
+        print("InvoiceTempl: \n%s" % InvoiceTempl)
+
+        optimized_str = InvoiceTempl.prepare_input(extracted_str)
+        print("extracted_str: \n%s" % extracted_str)
+        print("optimized_str: \n%s" % optimized_str)
+        self.assertEqual(optimized_str, "b")
+
+    def test_remove_accents(self):
+        OPTIONS_TEST = {
+            "currency": "EUR",
+            "date_formats": [],
+            "languages": ["aa"],
+            "decimal_separator": ".",
+            "remove_accents": True,
+        }
+
+        tpl = {}
+        tpl["keywords"] = ["Basic Test"]
+        tpl["exclude_keywords"] = []
+        tpl["options"] = OPTIONS_TEST
+        tpl["template_name"] = "test_remove_accents"
+        InvoiceTempl = InvoiceTemplate(tpl)
+        extracted_str = "é€$%^&*@!.a Málaga François Phút Hơn 中文"
+        print("InvoiceTempl: \n%s" % InvoiceTempl)
+
+        optimized_str = InvoiceTempl.prepare_input(extracted_str)
+        print("extracted_str: \n%s" % extracted_str)
+        print("optimized_str: \n%s\n" % optimized_str)
+        self.assertEqual(
+            optimized_str,
+            "e€$%^&*@!.a Malaga Francois Phut Hon 中文",
+            "Remove accents function failed, output not equal",
+        )
+
+    def test_remove_whitespace(self):
+        OPTIONS_TEST = {
+            "currency": "EUR",
+            "date_formats": [],
+            "languages": ["aa"],
+            "decimal_separator": ".",
+            "remove_whitespace": True,
+        }
+
+        tpl = {}
+        tpl["keywords"] = ["Basic Test"]
+        tpl["exclude_keywords"] = []
+        tpl["options"] = OPTIONS_TEST
+        tpl["template_name"] = "test_remove_whitespace"
+        InvoiceTempl = InvoiceTemplate(tpl)
+        extracted_str = "a     b"
+        print("InvoiceTempl: \n%s" % InvoiceTempl)
+
+        optimized_str = InvoiceTempl.prepare_input(extracted_str)
+        print("extracted_str: \n%s" % extracted_str)
+        print("optimized_str: \n%s\n" % optimized_str)
+        self.assertEqual(optimized_str, "ab", "remove whitespace test failed")
+
+    def test_lowercase(self):
+        OPTIONS_TEST = {
+            "currency": "EUR",
+            "date_formats": [],
+            "languages": ["aa"],
+            "decimal_separator": ".",
+            "lowercase": True,
+        }
+
+        tpl = {}
+        tpl["keywords"] = ["Basic Test"]
+        tpl["exclude_keywords"] = []
+        tpl["options"] = OPTIONS_TEST
+        tpl["template_name"] = "test_lowercase"
+        InvoiceTempl = InvoiceTemplate(tpl)
+        extracted_str = "ABCD"
+        print("InvoiceTempl: \n%s" % InvoiceTempl)
+
+        optimized_str = InvoiceTempl.prepare_input(extracted_str)
+        print("extracted_str: \n%s" % extracted_str)
+        print("optimized_str: \n%s\n" % optimized_str)
+        self.assertEqual(optimized_str, "abcd", "Lowercase test failed")
+
+
+if __name__ == "__main__":
+    unittest.main()