Improvements for more PEP compliance (duplicate imports, raise from, else's) (#125)

1. Removed duplicate imports
2. Added `raise from` for better exception tracing
3. Removed `else` in the check that handles the exception

Author: mrcnkwcz

email_validator/deliverability.py

@@ -72,12 +72,12 @@ def validate_email_deliverability(domain: str, domain_i18n: str, timeout: Option
                     deliverability_info["mx"] = [(0, str(r)) for r in response]
                     deliverability_info["mx_fallback_type"] = "AAAA"
 
-                except dns.resolver.NoAnswer:
+                except dns.resolver.NoAnswer as e:
                     # If there was no MX, A, or AAAA record, then mail to
                     # this domain is not deliverable, although the domain
                     # name has other records (otherwise NXDOMAIN would
                     # have been raised).
-                    raise EmailUndeliverableError(f"The domain name {domain_i18n} does not accept email.")
+                    raise EmailUndeliverableError(f"The domain name {domain_i18n} does not accept email.") from e
 
             # Check for a SPF (RFC 7208) reject-all record ("v=spf1 -all") which indicates
             # no emails are sent from this domain (similar to a Null MX record
@@ -96,10 +96,10 @@ def validate_email_deliverability(domain: str, domain_i18n: str, timeout: Option
                 # No TXT records means there is no SPF policy, so we cannot take any action.
                 pass
 
-    except dns.resolver.NXDOMAIN:
+    except dns.resolver.NXDOMAIN as e:
         # The domain name does not exist --- there are no records of any sort
         # for the domain name.
-        raise EmailUndeliverableError(f"The domain name {domain_i18n} does not exist.")
+        raise EmailUndeliverableError(f"The domain name {domain_i18n} does not exist.") from e
 
     except dns.resolver.NoNameservers:
         # All nameservers failed to answer the query. This might be a problem
@@ -122,6 +122,6 @@ def validate_email_deliverability(domain: str, domain_i18n: str, timeout: Option
         # Unhandled conditions should not propagate.
         raise EmailUndeliverableError(
             "There was an error while checking if the domain name in the email address is deliverable: " + str(e)
-        )
+        ) from e
 
     return deliverability_info

email_validator/exceptions_types.py

@@ -80,7 +80,6 @@ def __getattr__(self, key):
 
     @property
     def email(self):
-        import warnings
         warnings.warn("ValidatedEmail.email is deprecated and will be removed, use ValidatedEmail.normalized instead", DeprecationWarning)
         return self.normalized
 

email_validator/syntax.py

@@ -26,7 +26,6 @@ def split_email(email):
         # Since backslash-escaping is no longer needed because
         # the quotes are removed, remove backslash-escaping
         # to return in the normalized form.
-        import re
         local_part = re.sub(r"\\(.)", "\\1", local_part)
 
         return local_part, domain_part, True
@@ -72,14 +71,14 @@ def validate_email_local_part(local: str, allow_smtputf8: bool = True, allow_emp
     if len(local) == 0:
         if not allow_empty_local:
             raise EmailSyntaxError("There must be something before the @-sign.")
-        else:
-            # The caller allows an empty local part. Useful for validating certain
-            # Postfix aliases.
-            return {
-                "local_part": local,
-                "ascii_local_part": local,
-                "smtputf8": False,
-            }
+
+        # The caller allows an empty local part. Useful for validating certain
+        # Postfix aliases.
+        return {
+            "local_part": local,
+            "ascii_local_part": local,
+            "smtputf8": False,
+        }
 
     # Check the length of the local part by counting characters.
     # (RFC 5321 4.5.3.1.1)
@@ -191,8 +190,8 @@ def validate_email_local_part(local: str, allow_smtputf8: bool = True, allow_emp
         # want to have an unhandled exception later.
         try:
             local.encode("utf8")
-        except ValueError:
-            raise EmailSyntaxError("The email address contains an invalid character.")
+        except ValueError as e:
+            raise EmailSyntaxError("The email address contains an invalid character.") from e
 
         # If this address passes only by the quoted string form, re-quote it
         # and backslash-escape quotes and backslashes (removing any unnecessary
@@ -330,7 +329,7 @@ def validate_email_domain_name(domain, test_environment=False, globally_delivera
     try:
         domain = idna.uts46_remap(domain, std3_rules=False, transitional=False)
     except idna.IDNAError as e:
-        raise EmailSyntaxError(f"The part after the @-sign contains invalid characters ({e}).")
+        raise EmailSyntaxError(f"The part after the @-sign contains invalid characters ({e}).") from e
 
     # The domain part is made up dot-separated "labels." Each label must
     # have at least one character and cannot start or end with dashes, which
@@ -374,11 +373,11 @@ def validate_email_domain_name(domain, test_environment=False, globally_delivera
                 # the length check is applied to a string that is different from the
                 # one the user supplied. Also I'm not sure if the length check applies
                 # to the internationalized form, the IDNA ASCII form, or even both!
-                raise EmailSyntaxError("The email address is too long after the @-sign.")
+                raise EmailSyntaxError("The email address is too long after the @-sign.") from e
 
             # Other errors seem to not be possible because the call to idna.uts46_remap
             # would have already raised them.
-            raise EmailSyntaxError(f"The part after the @-sign contains invalid characters ({e}).")
+            raise EmailSyntaxError(f"The part after the @-sign contains invalid characters ({e}).") from e
 
         # Check the syntax of the string returned by idna.encode.
         # It should never fail.
@@ -440,7 +439,7 @@ def validate_email_domain_name(domain, test_environment=False, globally_delivera
     try:
         domain_i18n = idna.decode(ascii_domain.encode('ascii'))
     except idna.IDNAError as e:
-        raise EmailSyntaxError(f"The part after the @-sign is not valid IDNA ({e}).")
+        raise EmailSyntaxError(f"The part after the @-sign is not valid IDNA ({e}).") from e
 
     # Check for invalid characters after normalization. These
     # should never arise. See the similar checks above.
@@ -518,7 +517,7 @@ def validate_email_domain_literal(domain_literal):
         try:
             addr = ipaddress.IPv4Address(domain_literal)
         except ValueError as e:
-            raise EmailSyntaxError(f"The address in brackets after the @-sign is not valid: It is not an IPv4 address ({e}) or is missing an address literal tag.")
+            raise EmailSyntaxError(f"The address in brackets after the @-sign is not valid: It is not an IPv4 address ({e}) or is missing an address literal tag.") from e
 
         # Return the IPv4Address object and the domain back unchanged.
         return {
@@ -531,7 +530,7 @@ def validate_email_domain_literal(domain_literal):
         try:
             addr = ipaddress.IPv6Address(domain_literal[5:])
         except ValueError as e:
-            raise EmailSyntaxError(f"The IPv6 address in brackets after the @-sign is not valid ({e}).")
+            raise EmailSyntaxError(f"The IPv6 address in brackets after the @-sign is not valid ({e}).") from e
 
         # Return the IPv6Address object and construct a normalized
         # domain literal.

email_validator/validate_email.py

@@ -49,8 +49,8 @@ def validate_email(
     if not isinstance(email, str):
         try:
             email = email.decode("ascii")
-        except ValueError:
-            raise EmailSyntaxError("The email address is not valid ASCII.")
+        except ValueError as e:
+            raise EmailSyntaxError("The email address is not valid ASCII.") from e
 
     # Split the address into the local part (before the @-sign)
     # and the domain part (after the @-sign). Normally, there