Fix some pylint warnings

Add docstrings where they were missing and fix a too-long line

tests/scripts/check-test-cases.py

@@ -26,6 +26,7 @@ import re
 import sys
 
 class Results:
+    """Store file and line information about errors or warnings in test suites."""
     def __init__(self):
         self.errors = 0
         self.warnings = 0
@@ -41,6 +42,7 @@ class Results:
         self.warnings += 1
 
 def collect_test_directories():
+    """Get the relative path for the TLS and Crypto test directories."""
     if os.path.isdir('tests'):
         tests_dir = 'tests'
     elif os.path.isdir('suites'):
@@ -55,6 +57,7 @@ def collect_test_directories():
     return directories
 
 def check_description(results, seen, file_name, line_number, description):
+    """Check test case descriptions for errors."""
     if description in seen:
         results.error(file_name, line_number,
                       'Duplicate description (also line {})',

tests/scripts/mbedtls_test.py

@@ -310,7 +310,10 @@ class MbedTlsTest(BaseHostTest):
 
         param_bytes, length = self.test_vector_to_bytes(function_id,
                                                         dependencies, args)
-        self.send_kv(''.join('{:02x}'.format(x) for x in length), ''.join('{:02x}'.format(x) for x in param_bytes))
+        self.send_kv(
+            ''.join('{:02x}'.format(x) for x in length),
+            ''.join('{:02x}'.format(x) for x in param_bytes)
+        )
 
     @staticmethod
     def get_result(value):