diff --git a/tests/scripts/generate_pkcs7_tests.py b/tests/scripts/generate_pkcs7_tests.py
index 2bf3fe9..c8c60d4 100755
--- a/tests/scripts/generate_pkcs7_tests.py
+++ b/tests/scripts/generate_pkcs7_tests.py
@@ -29,18 +29,26 @@
 import sys
 from os.path import exists
 
-pkcs7_test_file =  "../suites/test_suite_pkcs7.data"
+PKCS7_TEST_FILE = "../suites/test_suite_pkcs7.data"
 
-class Test:
+class Test: # pylint: disable=too-few-public-methods
+    """
+    A instance of a test in test_suite_pkcs7.data
+    """
     def __init__(self, name, depends, func_call):
         self.name = name
         self.depends = depends
         self.func_call = func_call
 
+    # pylint: disable=no-self-use
     def to_string(self):
         return "\n" + self.name + "\n" + self.depends + "\n" + self.func_call + "\n"
 
 class TestData:
+    """
+    Take in test_suite_pkcs7.data file.
+    Allow for new tests to be added.
+    """
     mandatory_dep = "MBEDTLS_SHA256_C"
     test_name = "PKCS7 Parse Failure Invalid ASN1"
     test_function = "pkcs7_asn1_fail:"
@@ -50,18 +58,20 @@
         self.new_tests = []
 
     def read_test_file(self, file):
+        """
+        Parse the test_suite_pkcs7.data file.
+        """
         tests = []
         if not exists(file):
             print(file + " Does not exist")
-            quit(1)
-        f = open(file, "r")
-        data = f.read()
-        f.close()
+            sys.exit()
+        with open(file, "r", encoding='UTF-8') as fp:
+            data = fp.read()
         lines = [line.strip() for line in data.split('\n') if len(line.strip()) > 1]
         i = 0
         while i < len(lines):
             if "depends" in lines[i+1]:
-                tests.append(Test(lines[i],lines[i+1], lines[i+2]))
+                tests.append(Test(lines[i], lines[i+1], lines[i+2]))
                 i += 3
             else:
                 tests.append(Test(lines[i], None, lines[i+1]))
@@ -71,28 +81,32 @@
 
     def add(self, name, func_call):
         self.last_test_num += 1
-        self.new_tests.append(Test(self.test_name + ": " + name +  " #" + str(self.last_test_num), "depends_on:" + self.mandatory_dep, self.test_function + '"' + func_call + '"'))
+        self.new_tests.append(Test(self.test_name + ": " + name +  " #" + \
+                str(self.last_test_num), "depends_on:" + self.mandatory_dep, \
+                self.test_function + '"' + func_call + '"'))
 
     def write_changes(self):
-        f = open(self.file_name, 'a')
-        f.write("\n")
-        for t in self.new_tests:
-            f.write(t.to_string())
-        f.close()
+        with open(self.file_name, 'a', encoding='UTF-8') as fw:
+            fw.write("\n")
+            for t in self.new_tests:
+                fw.write(t.to_string())
 
 
 def asn1_mutate(data):
-    mutations = []
-    reasons = []
-    # we have been given an asn1 structure representing a pkcs7
-    # we want to return an array of slightly modified versions of this data
-    # they should be modified in a way which makes the structure invalid
+    """
+    We have been given an asn1 structure representing a pkcs7.
+    We want to return an array of slightly modified versions of this data
+    they should be modified in a way which makes the structure invalid
 
-    # we know that asn1 structures are:
-    # |---1 byte showing data type---|----byte(s) for length of data---|---data content--|
-    # we know that some data types can contain other data types
+    We know that asn1 structures are:
+    |---1 byte showing data type---|----byte(s) for length of data---|---data content--|
+    We know that some data types can contain other data types.
+    Return a dictionary of reasons and mutated data types.
+    """
 
     # off the bat just add bytes to start and end of the buffer
+    mutations = []
+    reasons = []
     mutations.append(["00"] + data)
     reasons.append("Add null byte to start")
     mutations.append(data + ["00"])
@@ -112,7 +126,8 @@
             length = int(data[leng_i], 16)
 
         tag = data[tag_i]
-        print("Looking at ans1: offset " + str(i) + " tag = " + tag + ", length = " + str(length)+ ":")
+        print("Looking at ans1: offset " + str(i) + " tag = " + tag + \
+                ", length = " + str(length)+ ":")
         print(''.join(data[data_i:data_i+length]))
         # change tag to something else
         if tag == "02":
@@ -131,11 +146,16 @@
             if len(new_length) == 1:
                 new_length = "0"+new_length
             mutations.append(data[:data_i -1] + [new_length] + data[data_i:])
-            reasons.append("Change length from " + str(length) + " to " + str(length + 1))
-            # we can add another test here for tags that contain other tags where they have more data than there containing tags account for
+            reasons.append("Change length from " + str(length) + " to " \
+                    + str(length + 1))
+            # we can add another test here for tags that contain other tags \
+            # where they have more data than there containing tags account for
             if tag in ["30", "a0", "31"]:
-                mutations.append(data[:data_i -1] + [new_length] + data[data_i:data_i + length] + ["00"] + data[data_i + length:])
-                reasons.append("Change contents of tag " + tag + " to contain one unaccounted extra byte")
+                mutations.append(data[:data_i -1] + [new_length] + \
+                        data[data_i:data_i + length] + ["00"] + \
+                        data[data_i + length:])
+                reasons.append("Change contents of tag " + tag + " to contain \
+                        one unaccounted extra byte")
         # change lengths to too small
         if int(data[data_i - 1], 16) > 0:
             new_length = str(hex(int(data[data_i - 1], 16) - 1))[2:]
@@ -152,24 +172,23 @@
 
     return list(zip(reasons, mutations))
 
-if len(sys.argv) < 2:
-    print("USAGE: " + sys.argv[0] + " <pkcs7_der_file>")
-    quit(1)
+if __name__ == "__main__":
+    if len(sys.argv) < 2:
+        print("USAGE: " + sys.argv[0] + " <pkcs7_der_file>")
+        sys.exit()
 
-data_file = sys.argv[1]
-test_data = TestData(pkcs7_test_file)
-f = open(data_file, 'rb')
-data_str = f.read().hex()
-f.close()
-# make data an array of byte strings eg ['de','ad','be','ef']
-data = list(map(''.join, [[data_str[i], data_str[i+1]] for i in range(0,len(data_str),2)]))
-# returns tuples of test_names and modified data buffers
-mutations = asn1_mutate(data)
+    DATA_FILE = sys.argv[1]
+    TEST_DATA = TestData(PKCS7_TEST_FILE)
+    with open(DATA_FILE, 'rb') as f:
+        DATA_STR = f.read().hex()
+    # make data an array of byte strings eg ['de','ad','be','ef']
+    HEX_DATA = list(map(''.join, [[DATA_STR[i], DATA_STR[i+1]] for i in range(0, len(DATA_STR), \
+            2)]))
+    # returns tuples of test_names and modified data buffers
+    MUT_ARR = asn1_mutate(HEX_DATA)
 
-print("made " + str(len(mutations)) + " new tests")
-for new_test in mutations:
-    test_data.add(new_test[0], ''.join(new_test[1]))
+    print("made " + str(len(MUT_ARR)) + " new tests")
+    for new_test in MUT_ARR:
+        TEST_DATA.add(new_test[0], ''.join(new_test[1]))
 
-
-test_data.write_changes()
-
+    TEST_DATA.write_changes()