minor: AWS auth spec test fixes (#232)

Author: saghm

src/client/auth/mod.rs

@@ -122,6 +122,18 @@ impl AuthMechanism {
                 };
                 Ok(())
             }
+            #[cfg(feature = "tokio-runtime")]
+            AuthMechanism::MongoDbAws => {
+                if credential.username.is_some() && credential.password.is_none() {
+                    return Err(ErrorKind::ArgumentError {
+                        message: "Username cannot be provided without password for MONGODB-AWS \
+                                  authentication"
+                            .to_string(),
+                    }
+                    .into());
+                }
+                Ok(())
+            }
             _ => Ok(()),
         }
     }

src/client/options/mod.rs

@@ -834,6 +834,19 @@ fn validate_userinfo(s: &str, userinfo_type: &str) -> Result<()> {
         }
         .into());
     }
+
+    // All instances of '%' in the username must be part of an percent-encoded substring. This means
+    // that there must be two hexidecimal digits following any '%' in the username.
+    if s.split('%')
+        .skip(1)
+        .any(|part| part.len() < 2 || part[0..2].chars().any(|c| !c.is_ascii_hexdigit()))
+    {
+        return Err(ErrorKind::ArgumentError {
+            message: "username/password cannot contain unescaped %".to_string(),
+        }
+        .into());
+    }
+
     Ok(())
 }
 
@@ -1018,12 +1031,6 @@ impl ClientOptionsParser {
             let mut credential = options.credential.get_or_insert_with(Default::default);
             validate_userinfo(u, "username")?;
             let decoded_u = percent_decode(u, "username must be URL encoded")?;
-            if decoded_u.chars().any(|c| c == '%') {
-                return Err(ErrorKind::ArgumentError {
-                    message: "username/passowrd cannot contain unescaped %".to_string(),
-                }
-                .into());
-            }
 
             credential.username = Some(decoded_u);
 

src/test/spec/auth.rs

@@ -55,6 +55,7 @@ async fn run_auth_test(test_file: TestFile) {
             "MONGODB-X509",
             "PLAIN",
             "MONGODB-CR",
+            #[cfg(not(feature = "tokio-runtime"))]
             "MONGODB-AWS",
         ];
 
@@ -84,7 +85,11 @@ async fn run_auth_test(test_file: TestFile) {
                     None => assert!(options.credential.is_none(), "{}", test_case.description),
                 }
             }
-            Err(_) => assert!(!test_case.valid, "{}", test_case.description),
+            Err(e) => assert!(
+                !test_case.valid,
+                "got error {:?}: {}",
+                e, test_case.description
+            ),
         };
     }
 }