initial removal of MongoAuthenticationMechanism enum

craiggwilson · craiggwilson · commit 3e1f52f248d8 · 2013-02-11T10:09:02.000-06:00
diff --git a/MongoDB.Driver/Communication/Security/Mechanisms/GssapiMechanism.cs b/MongoDB.Driver/Communication/Security/Mechanisms/GssapiMechanism.cs
@@ -49,7 +49,7 @@ public string Name
         /// <exception cref="System.NotImplementedException"></exception>
         public bool CanUse(MongoCredential credential)
         {
-            if (credential.Mechanism != MongoAuthenticationMechanism.Gssapi || !(credential.Identity is MongoExternalIdentity))
+            if (!credential.Mechanism.Equals("GSSAPI", StringComparison.InvariantCultureIgnoreCase) || !(credential.Identity is MongoExternalIdentity))
             {
                 return false;
             }
diff --git a/MongoDB.Driver/Communication/Security/MongoCRAuthenticationProtocol.cs b/MongoDB.Driver/Communication/Security/MongoCRAuthenticationProtocol.cs
@@ -77,8 +77,8 @@ public void Authenticate(MongoConnection connection, MongoCredential credential)
         /// </returns>
         public bool CanUse(MongoCredential credential)
         {
-            return credential.Mechanism == MongoAuthenticationMechanism.Mongo_CR &&
+            return credential.Mechanism.Equals("MONGO-CR", StringComparison.InvariantCultureIgnoreCase) &&
                 credential.Evidence is PasswordEvidence;
         }
     }
-}
+}
diff --git a/MongoDB.Driver/MongoAuthenticationMechanism.cs b/MongoDB.Driver/MongoAuthenticationMechanism.cs
diff --git a/MongoDB.Driver/MongoConnectionStringBuilder.cs b/MongoDB.Driver/MongoConnectionStringBuilder.cs
@@ -75,7 +75,7 @@ public class MongoConnectionStringBuilder : DbConnectionStringBuilder
 
         // private fields
         // default values are set in ResetValues
-        private MongoAuthenticationMechanism _authenticationMechanism;
+        private string _authenticationMechanism;
         private string _authenticationSource;
         private ConnectionMode _connectionMode;
         private TimeSpan _connectTimeout;
@@ -127,16 +127,12 @@ public MongoConnectionStringBuilder(string connectionString)
         /// <summary>
         /// Gets or sets the authentication mechanism.
         /// </summary>
-        public MongoAuthenticationMechanism AuthenticationMechanism
+        public string AuthenticationMechanism
         {
             get { return _authenticationMechanism; }
             set 
             {
-                _authenticationMechanism = value;
-                base["authMechanism"] = value
-                    .ToString()
-                    .ToUpper()
-                    .Replace("_", "-");
+                base["authMechanism"] = _authenticationMechanism = value;
             }
         }
 
@@ -674,15 +670,7 @@ public override object this[string keyword]
                 switch (keyword.ToLower())
                 {
                     case "authmechanism":
-                        if (value is string)
-                        {
-                            string mechanism = ((string)value).Replace("-", "_");
-                            AuthenticationMechanism = (MongoAuthenticationMechanism)Enum.Parse(typeof(MongoAuthenticationMechanism), mechanism, true);
-                        }
-                        else
-                        {
-                            AuthenticationMechanism = (MongoAuthenticationMechanism)value;
-                        }
+                        AuthenticationMechanism = (string)value;
                         break;
                     case "authsource":
                         AuthenticationSource = (string)value;
@@ -966,7 +954,7 @@ private IEnumerable<MongoServerAddress> ParseServersString(string value)
         private void ResetValues()
         {
             // set fields and not properties so base class items aren't set
-            _authenticationMechanism = MongoAuthenticationMechanism.Mongo_CR;
+            _authenticationMechanism = MongoDefaults.AuthenticationMechanism;
             _authenticationSource = null;
             _connectionMode = ConnectionMode.Automatic;
             _connectTimeout = MongoDefaults.ConnectTimeout;
diff --git a/MongoDB.Driver/MongoCredential.cs b/MongoDB.Driver/MongoCredential.cs
@@ -29,7 +29,7 @@ public class MongoCredential : IEquatable<MongoCredential>
         // private fields
         private readonly MongoIdentityEvidence _evidence;
         private readonly MongoIdentity _identity;
-        private readonly MongoAuthenticationMechanism _mechanism;
+        private readonly string _mechanism;
         
         // constructors
         /// <summary>
@@ -38,7 +38,7 @@ public class MongoCredential : IEquatable<MongoCredential>
         /// <param name="mechanism">Mechanism to authenticate with.</param>
         /// <param name="identity">The identity.</param>
         /// <param name="evidence">The evidence.</param>
-        public MongoCredential(MongoAuthenticationMechanism mechanism, MongoIdentity identity, MongoIdentityEvidence evidence)
+        public MongoCredential(string mechanism, MongoIdentity identity, MongoIdentityEvidence evidence)
         {
             if (identity == null)
             {
@@ -74,7 +74,7 @@ public MongoIdentity Identity
         /// <summary>
         /// Gets the mechanism to authenticate with.
         /// </summary>
-        public MongoAuthenticationMechanism Mechanism
+        public string Mechanism
         {
             get { return _mechanism; }
         }
@@ -145,7 +145,7 @@ public string Username
         /// <remarks>This overload is used primarily on linux.</remarks>
         public static MongoCredential CreateGssapiCredential(string username)
         {
-            return FromComponents(MongoAuthenticationMechanism.Gssapi,
+            return FromComponents("GSSAPI",
                 "$external",
                 username,
                 (PasswordEvidence)null);
@@ -159,7 +159,7 @@ public static MongoCredential CreateGssapiCredential(string username)
         /// <returns>A credential for GSSAPI.</returns>
         public static MongoCredential CreateGssapiCredential(string username, string password)
         {
-            return FromComponents(MongoAuthenticationMechanism.Gssapi,
+            return FromComponents("GSSAPI",
                 "$external",
                 username,
                 new PasswordEvidence(password));
@@ -173,7 +173,7 @@ public static MongoCredential CreateGssapiCredential(string username, string pas
         /// <returns>A credential for GSSAPI.</returns>
         public static MongoCredential CreateGssapiCredential(string username, SecureString password)
         {
-            return FromComponents(MongoAuthenticationMechanism.Gssapi,
+            return FromComponents("GSSAPI",
                 "$external",
                 username,
                 new PasswordEvidence(password));
@@ -188,7 +188,7 @@ public static MongoCredential CreateGssapiCredential(string username, SecureStri
         /// <returns></returns>
         public static MongoCredential CreateMongoCRCredential(string databaseName, string username, string password)
         {
-            return FromComponents(MongoAuthenticationMechanism.Mongo_CR,
+            return FromComponents("MONGO-CR",
                 databaseName,
                 username,
                 new PasswordEvidence(password));
@@ -203,7 +203,7 @@ public static MongoCredential CreateMongoCRCredential(string databaseName, strin
         /// <returns></returns>
         public static MongoCredential CreateMongoCRCredential(string databaseName, string username, SecureString password)
         {
-            return FromComponents(MongoAuthenticationMechanism.Mongo_CR,
+            return FromComponents("MONGO-CR",
                 databaseName,
                 username,
                 new PasswordEvidence(password));
@@ -255,7 +255,7 @@ public override string ToString()
         }
 
         // internal static methods
-        internal static MongoCredential FromComponents(MongoAuthenticationMechanism mechanism, string source, string username, string password)
+        internal static MongoCredential FromComponents(string mechanism, string source, string username, string password)
         {
             var evidence = password == null ? (MongoIdentityEvidence)new ExternalEvidence() : new PasswordEvidence(password);
             return FromComponents(mechanism, source, username, evidence);
@@ -275,41 +275,45 @@ private void ValidatePassword(string password)
         }
 
         // private static methods
-        private static MongoCredential FromComponents(MongoAuthenticationMechanism mechanism, string source, string username, MongoIdentityEvidence evidence)
+        private static MongoCredential FromComponents(string mechanism, string source, string username, MongoIdentityEvidence evidence)
         {
+            if (string.IsNullOrEmpty(mechanism))
+            {
+                throw new ArgumentException("Cannot be null or empty.", "mechanism");
+            }
             if (string.IsNullOrEmpty(username))
             {
                 return null;
             }
 
-            switch (mechanism)
+            switch (mechanism.ToUpperInvariant())
             {
-                case MongoAuthenticationMechanism.Mongo_CR:
+                case "MONGO-CR":
                     // it is allowed for a password to be an empty string, but not a username
                     source = source ?? "admin";
                     if (evidence == null || !(evidence is PasswordEvidence))
                     {
-                        throw new ArgumentException(string.Format("A {0} credential must have a password.", mechanism));
+                        throw new ArgumentException("A MONGO-CR credential must have a password.");
                     }
 
                     return new MongoCredential(
                         mechanism,
                         new MongoInternalIdentity(source, username),
                         evidence);
-                case MongoAuthenticationMechanism.Gssapi:
+                case "GSSAPI":
                     source = source ?? "$external";
                     if (source != "$external")
                     {
                         throw new ArgumentException("The source for GSSAPI must be $external.");
                     }
 
                     return new MongoCredential(
-                        MongoAuthenticationMechanism.Gssapi,
+                        "GSSAPI",
                         new MongoExternalIdentity(source, username),
                         evidence);
                 default:
                     throw new NotSupportedException(string.Format("Unsupported MongoAuthenticationMechanism {0}.", mechanism));
             }
         }
     }
-}
+}
diff --git a/MongoDB.Driver/MongoDB.Driver.csproj b/MongoDB.Driver/MongoDB.Driver.csproj
@@ -170,7 +170,6 @@
     <Compile Include="IMongoScope.cs" />
     <Compile Include="IMongoSortBy.cs" />
     <Compile Include="IMongoUpdate.cs" />
-    <Compile Include="MongoAuthenticationMechanism.cs" />
     <Compile Include="MongoClient.cs" />
     <Compile Include="MongoClientSettings.cs" />
     <Compile Include="MongoCollectionSettings.cs" />
diff --git a/MongoDB.Driver/MongoDefaults.cs b/MongoDB.Driver/MongoDefaults.cs
@@ -25,6 +25,7 @@ public static class MongoDefaults
     {
         // private static fields
         private static bool __assignIdOnInsert = true;
+        private static string __authenticationMechanism = "MONGO-CR";
         private static TimeSpan __connectTimeout = TimeSpan.FromSeconds(30);
         private static TimeSpan __maxConnectionIdleTime = TimeSpan.FromMinutes(10);
         private static TimeSpan __maxConnectionLifeTime = TimeSpan.FromMinutes(30);
@@ -52,6 +53,15 @@ public static bool AssignIdOnInsert
             set { __assignIdOnInsert = value; }
         }
 
+        /// <summary>
+        /// Gets or sets the default authentication mechanism.
+        /// </summary>
+        public static string AuthenticationMechanism
+        {
+            get { return __authenticationMechanism; }
+            set { __authenticationMechanism = value; }
+        }
+
         /// <summary>
         /// Gets the actual wait queue size (either WaitQueueSize or WaitQueueMultiple x MaxConnectionPoolSize).
         /// </summary>
diff --git a/MongoDB.Driver/MongoUrl.cs b/MongoDB.Driver/MongoUrl.cs
@@ -55,7 +55,7 @@ public class MongoUrl : IEquatable<MongoUrl>
         private static Dictionary<string, MongoUrl> __cache = new Dictionary<string, MongoUrl>();
 
         // private fields
-        private readonly MongoAuthenticationMechanism _authenticationMechanism;
+        private readonly string _authenticationMechanism;
         private readonly string _authenticationSource;
         private readonly ConnectionMode _connectionMode;
         private readonly TimeSpan _connectTimeout;
@@ -130,7 +130,7 @@ public MongoUrl(string url)
         /// <summary>
         /// Gets the authentication mechanism.
         /// </summary>
-        public MongoAuthenticationMechanism AuthenticationMechanism
+        public string AuthenticationMechanism
         {
             get { return _authenticationMechanism; }
         }
diff --git a/MongoDB.Driver/MongoUrlBuilder.cs b/MongoDB.Driver/MongoUrlBuilder.cs
@@ -31,7 +31,7 @@ namespace MongoDB.Driver
     public class MongoUrlBuilder
     {
         // private fields
-        private MongoAuthenticationMechanism _authenticationMechanism;
+        private string _authenticationMechanism;
         private string _authenticationSource;
         private ConnectionMode _connectionMode;
         private TimeSpan _connectTimeout;
@@ -66,7 +66,7 @@ public class MongoUrlBuilder
         /// </summary>
         public MongoUrlBuilder()
         {
-            _authenticationMechanism = MongoAuthenticationMechanism.Mongo_CR;
+            _authenticationMechanism = MongoDefaults.AuthenticationMechanism;
             _authenticationSource = null;
             _connectionMode = ConnectionMode.Automatic;
             _connectTimeout = MongoDefaults.ConnectTimeout;
@@ -110,7 +110,7 @@ public MongoUrlBuilder(string url)
         /// <summary>
         /// Gets or sets the authentication mechanism.
         /// </summary>
-        public MongoAuthenticationMechanism AuthenticationMechanism
+        public string AuthenticationMechanism
         {
             get { return _authenticationMechanism; }
             set { _authenticationMechanism = value; }
@@ -588,20 +588,6 @@ internal static string FormatTimeSpan(TimeSpan value)
             }
         }
 
-        internal static MongoAuthenticationMechanism ParseAuthenticationMechanism(string name, string s)
-        {
-            try
-            {
-                // enumerations cannot use -'s, so we replace them with _'s.
-                s = s.Replace("-", "_");
-                return (MongoAuthenticationMechanism)Enum.Parse(typeof(MongoAuthenticationMechanism), s, true); // ignoreCase
-            }
-            catch (ArgumentException)
-            {
-                throw new FormatException(FormatMessage(name, s));
-            }
-        }
-
         internal static ConnectionMode ParseConnectionMode(string name, string s)
         {
             try
@@ -827,7 +813,7 @@ public void Parse(string url)
                         switch (name.ToLower())
                         {
                             case "authmechanism":
-                                _authenticationMechanism = ParseAuthenticationMechanism(name, value);
+                                _authenticationMechanism = value;
                                 break;
                             case "authsource":
                                 _authenticationSource = value;
@@ -1014,14 +1000,9 @@ public override string ToString()
                 url.Append(_databaseName);
             }
             var query = new StringBuilder();
-            if (_authenticationMechanism != MongoAuthenticationMechanism.Mongo_CR)
+            if (!_authenticationMechanism.Equals("MONGO-CR", StringComparison.InvariantCultureIgnoreCase))
             {
-                string mechanismName = _authenticationMechanism
-                    .ToString()
-                    .ToUpper()
-                    .Replace("_", "-");
-
-                query.AppendFormat("authMechanism={0};", mechanismName);
+                query.AppendFormat("authMechanism={0};", _authenticationMechanism);
             }
             if (_authenticationSource != null)
             {
diff --git a/MongoDB.DriverUnitTests/MongoConnectionStringBuilderTests.cs b/MongoDB.DriverUnitTests/MongoConnectionStringBuilderTests.cs
@@ -37,7 +37,7 @@ public void TestAll()
             };
             var built = new MongoConnectionStringBuilder()
             {
-                AuthenticationMechanism = MongoAuthenticationMechanism.Gssapi,
+                AuthenticationMechanism = "GSSAPI",
                 AuthenticationSource = "db",
                 ConnectionMode = ConnectionMode.ReplicaSet,
                 ConnectTimeout = TimeSpan.FromSeconds(1),
@@ -96,7 +96,7 @@ public void TestAll()
 
             foreach (var builder in EnumerateBuiltAndParsedBuilders(built, connectionString))
             {
-                Assert.AreEqual(MongoAuthenticationMechanism.Gssapi, builder.AuthenticationMechanism);
+                Assert.AreEqual("GSSAPI", builder.AuthenticationMechanism);
                 Assert.AreEqual("db", builder.AuthenticationSource);
                 Assert.AreEqual(123, builder.ComputedWaitQueueSize);
                 Assert.AreEqual(ConnectionMode.ReplicaSet, builder.ConnectionMode);
@@ -135,9 +135,9 @@ public void TestAll()
         }
 
         [Test]
-        [TestCase(MongoAuthenticationMechanism.Mongo_CR, "server=localhost;authMechanism=MONGO-CR")]
-        [TestCase(MongoAuthenticationMechanism.Gssapi, "server=localhost;authMechanism=GSSAPI")]
-        public void TestAuthMechanism(MongoAuthenticationMechanism mechanism, string connectionString)
+        [TestCase("MONGO-CR", "server=localhost;authMechanism=MONGO-CR")]
+        [TestCase("GSSAPI", "server=localhost;authMechanism=GSSAPI")]
+        public void TestAuthMechanism(string mechanism, string connectionString)
         {
             var built = new MongoConnectionStringBuilder { Server = _localhost, AuthenticationMechanism = mechanism };
 
diff --git a/MongoDB.DriverUnitTests/MongoUrlBuilderTests.cs b/MongoDB.DriverUnitTests/MongoUrlBuilderTests.cs
diff --git a/MongoDB.DriverUnitTests/MongoUrlTests.cs b/MongoDB.DriverUnitTests/MongoUrlTests.cs

Original file line number	Diff line number	Diff line change
`@@ -49,7 +49,7 @@ public string Name`
`49`	`49`	`/// <exception cref="System.NotImplementedException"></exception>`
`50`	`50`	`public bool CanUse(MongoCredential credential)`
`51`	`51`	`{`
`52`		`- if (credential.Mechanism != MongoAuthenticationMechanism.Gssapi \|\| !(credential.Identity is MongoExternalIdentity))`
	`52`	`+ if (!credential.Mechanism.Equals("GSSAPI", StringComparison.InvariantCultureIgnoreCase) \|\| !(credential.Identity is MongoExternalIdentity))`
`53`	`53`	`{`
`54`	`54`	`return false;`
`55`	`55`	`}`
Original file line number	Diff line number	Diff line change
`@@ -77,8 +77,8 @@ public void Authenticate(MongoConnection connection, MongoCredential credential)`
`77`	`77`	`/// </returns>`
`78`	`78`	`public bool CanUse(MongoCredential credential)`
`79`	`79`	`{`
`80`		`- return credential.Mechanism == MongoAuthenticationMechanism.Mongo_CR &&`
	`80`	`+ return credential.Mechanism.Equals("MONGO-CR", StringComparison.InvariantCultureIgnoreCase) &&`
`81`	`81`	`credential.Evidence is PasswordEvidence;`
`82`	`82`	`}`
`83`	`83`	`}`
`84`		`-}`
	`84`	`+}`
Original file line number	Diff line number	Diff line change
`@@ -29,7 +29,7 @@ public class MongoCredential : IEquatable<MongoCredential>`
`29`	`29`	`// private fields`
`30`	`30`	`private readonly MongoIdentityEvidence _evidence;`
`31`	`31`	`private readonly MongoIdentity _identity;`
`32`		`- private readonly MongoAuthenticationMechanism _mechanism;`
	`32`	`+ private readonly string _mechanism;`
`33`	`33`
`34`	`34`	`// constructors`
`35`	`35`	`/// <summary>`
`@@ -38,7 +38,7 @@ public class MongoCredential : IEquatable<MongoCredential>`
`38`	`38`	`/// <param name="mechanism">Mechanism to authenticate with.</param>`
`39`	`39`	`/// <param name="identity">The identity.</param>`
`40`	`40`	`/// <param name="evidence">The evidence.</param>`
`41`		`- public MongoCredential(MongoAuthenticationMechanism mechanism, MongoIdentity identity, MongoIdentityEvidence evidence)`
	`41`	`+ public MongoCredential(string mechanism, MongoIdentity identity, MongoIdentityEvidence evidence)`
`42`	`42`	`{`
`43`	`43`	`if (identity == null)`
`44`	`44`	`{`
`@@ -74,7 +74,7 @@ public MongoIdentity Identity`
`74`	`74`	`/// <summary>`
`75`	`75`	`/// Gets the mechanism to authenticate with.`
`76`	`76`	`/// </summary>`
`77`		`- public MongoAuthenticationMechanism Mechanism`
	`77`	`+ public string Mechanism`
`78`	`78`	`{`
`79`	`79`	`get { return _mechanism; }`
`80`	`80`	`}`
`@@ -145,7 +145,7 @@ public string Username`
`145`	`145`	`/// <remarks>This overload is used primarily on linux.</remarks>`
`146`	`146`	`public static MongoCredential CreateGssapiCredential(string username)`
`147`	`147`	`{`
`148`		`- return FromComponents(MongoAuthenticationMechanism.Gssapi,`
	`148`	`+ return FromComponents("GSSAPI",`
`149`	`149`	`"$external",`
`150`	`150`	`username,`
`151`	`151`	`(PasswordEvidence)null);`
`@@ -159,7 +159,7 @@ public static MongoCredential CreateGssapiCredential(string username)`
`159`	`159`	`/// <returns>A credential for GSSAPI.</returns>`
`160`	`160`	`public static MongoCredential CreateGssapiCredential(string username, string password)`
`161`	`161`	`{`
`162`		`- return FromComponents(MongoAuthenticationMechanism.Gssapi,`
	`162`	`+ return FromComponents("GSSAPI",`
`163`	`163`	`"$external",`
`164`	`164`	`username,`
`165`	`165`	`new PasswordEvidence(password));`
`@@ -173,7 +173,7 @@ public static MongoCredential CreateGssapiCredential(string username, string pas`
`173`	`173`	`/// <returns>A credential for GSSAPI.</returns>`
`174`	`174`	`public static MongoCredential CreateGssapiCredential(string username, SecureString password)`
`175`	`175`	`{`
`176`		`- return FromComponents(MongoAuthenticationMechanism.Gssapi,`
	`176`	`+ return FromComponents("GSSAPI",`
`177`	`177`	`"$external",`
`178`	`178`	`username,`
`179`	`179`	`new PasswordEvidence(password));`
`@@ -188,7 +188,7 @@ public static MongoCredential CreateGssapiCredential(string username, SecureStri`
`188`	`188`	`/// <returns></returns>`
`189`	`189`	`public static MongoCredential CreateMongoCRCredential(string databaseName, string username, string password)`
`190`	`190`	`{`
`191`		`- return FromComponents(MongoAuthenticationMechanism.Mongo_CR,`
	`191`	`+ return FromComponents("MONGO-CR",`
`192`	`192`	`databaseName,`
`193`	`193`	`username,`
`194`	`194`	`new PasswordEvidence(password));`
`@@ -203,7 +203,7 @@ public static MongoCredential CreateMongoCRCredential(string databaseName, strin`
`203`	`203`	`/// <returns></returns>`
`204`	`204`	`public static MongoCredential CreateMongoCRCredential(string databaseName, string username, SecureString password)`
`205`	`205`	`{`
`206`		`- return FromComponents(MongoAuthenticationMechanism.Mongo_CR,`
	`206`	`+ return FromComponents("MONGO-CR",`
`207`	`207`	`databaseName,`
`208`	`208`	`username,`
`209`	`209`	`new PasswordEvidence(password));`
`@@ -255,7 +255,7 @@ public override string ToString()`
`255`	`255`	`}`
`256`	`256`
`257`	`257`	`// internal static methods`
`258`		`- internal static MongoCredential FromComponents(MongoAuthenticationMechanism mechanism, string source, string username, string password)`
	`258`	`+ internal static MongoCredential FromComponents(string mechanism, string source, string username, string password)`
`259`	`259`	`{`
`260`	`260`	`var evidence = password == null ? (MongoIdentityEvidence)new ExternalEvidence() : new PasswordEvidence(password);`
`261`	`261`	`return FromComponents(mechanism, source, username, evidence);`
`@@ -275,41 +275,45 @@ private void ValidatePassword(string password)`
`275`	`275`	`}`
`276`	`276`
`277`	`277`	`// private static methods`
`278`		`- private static MongoCredential FromComponents(MongoAuthenticationMechanism mechanism, string source, string username, MongoIdentityEvidence evidence)`
	`278`	`+ private static MongoCredential FromComponents(string mechanism, string source, string username, MongoIdentityEvidence evidence)`
`279`	`279`	`{`
	`280`	`+ if (string.IsNullOrEmpty(mechanism))`
	`281`	`+ {`
	`282`	`+ throw new ArgumentException("Cannot be null or empty.", "mechanism");`
	`283`	`+ }`
`280`	`284`	`if (string.IsNullOrEmpty(username))`
`281`	`285`	`{`
`282`	`286`	`return null;`
`283`	`287`	`}`
`284`	`288`
`285`		`- switch (mechanism)`
	`289`	`+ switch (mechanism.ToUpperInvariant())`
`286`	`290`	`{`
`287`		`- case MongoAuthenticationMechanism.Mongo_CR:`
	`291`	`+ case "MONGO-CR":`
`288`	`292`	`// it is allowed for a password to be an empty string, but not a username`
`289`	`293`	`source = source ?? "admin";`
`290`	`294`	`if (evidence == null \|\| !(evidence is PasswordEvidence))`
`291`	`295`	`{`
`292`		`- throw new ArgumentException(string.Format("A {0} credential must have a password.", mechanism));`
	`296`	`+ throw new ArgumentException("A MONGO-CR credential must have a password.");`
`293`	`297`	`}`
`294`	`298`
`295`	`299`	`return new MongoCredential(`
`296`	`300`	`mechanism,`
`297`	`301`	`new MongoInternalIdentity(source, username),`
`298`	`302`	`evidence);`
`299`		`- case MongoAuthenticationMechanism.Gssapi:`
	`303`	`+ case "GSSAPI":`
`300`	`304`	`source = source ?? "$external";`
`301`	`305`	`if (source != "$external")`
`302`	`306`	`{`
`303`	`307`	`throw new ArgumentException("The source for GSSAPI must be $external.");`
`304`	`308`	`}`
`305`	`309`
`306`	`310`	`return new MongoCredential(`
`307`		`- MongoAuthenticationMechanism.Gssapi,`
	`311`	`+ "GSSAPI",`
`308`	`312`	`new MongoExternalIdentity(source, username),`
`309`	`313`	`evidence);`
`310`	`314`	`default:`
`311`	`315`	`throw new NotSupportedException(string.Format("Unsupported MongoAuthenticationMechanism {0}.", mechanism));`
`312`	`316`	`}`
`313`	`317`	`}`
`314`	`318`	`}`
`315`		`-}`
	`319`	`+}`