Initial commit with repro case for nhibernate/nhibernate-core#1277

.gitignore

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+.vs/
+bin/
+obj/

NHibernate-MbC-join-mapping.sln

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+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 15
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NHibernate.Tests", "NHibernate.Tests\NHibernate.Tests.csproj", "{2244649E-15A9-4A35-8B26-8A174F7CC50A}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{2244649E-15A9-4A35-8B26-8A174F7CC50A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{2244649E-15A9-4A35-8B26-8A174F7CC50A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{2244649E-15A9-4A35-8B26-8A174F7CC50A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{2244649E-15A9-4A35-8B26-8A174F7CC50A}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+EndGlobal

NHibernate.Tests/CreateDb.sql

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+BEGIN TRANSACTION;
+
+-- Schema
+CREATE TABLE Person (
+    PersonId INT PRIMARY KEY,
+    Name VARCHAR
+);
+CREATE TABLE Address (
+    AddressId INT PRIMARY KEY,
+    AddressPersonId INT NOT NULL,
+    City VARCHAR,
+    CONSTRAINT FK_ADDRESS_HAS_PERSON FOREIGN KEY (AddressPersonId) REFERENCES Person
+);
+CREATE TABLE PayrollInfo (
+    PayrollInfoId INT PRIMARY KEY,
+    PayrollInfoPersonId INT NOT NULL,
+    PayrollNumber INT,
+    CONSTRAINT FK_PAYROLLINFO_HAS_PERSON FOREIGN KEY (PayrollInfoId) REFERENCES Person
+);
+
+COMMIT;
+
+BEGIN TRANSACTION;
+
+-- Data
+INSERT INTO Person(PersonId, Name)
+VALUES(1, 'Jane Doe');
+INSERT INTO Address(AddressPersonId, City)
+VALUES(1, 'Nowhere');
+INSERT INTO PayrollInfo(PayrollInfoPersonId, PayrollNumber)
+VALUES(1, 1234);
+
+COMMIT;

NHibernate.Tests/DbInitializer.cs

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+using System;
+using System.Data;
+using System.Data.Common;
+using System.IO;
+using System.Reflection;
+
+namespace NHibernate.Tests
+{
+    /// <summary>
+    /// Initializer class executes the script <c>CreateDb.sql</c> on the specified connection.
+    /// </summary>
+    public class DbInitializer
+    {
+        public void InitializeDatabase(DbConnection connection)
+        {
+            if (connection == null)
+                throw new ArgumentNullException(nameof(connection));
+
+            if (connection.State != ConnectionState.Open)
+                connection.Open();
+
+            var initScript = GetInitScript();
+            ExecuteScript(connection, initScript);
+        }
+
+        string GetInitScript()
+        {
+            using (var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream("NHibernate.Tests.CreateDb.sql"))
+            using(var reader = new StreamReader(stream))
+            {
+                return reader.ReadToEnd();
+            }
+        }
+
+        void ExecuteScript(DbConnection connection, string script)
+        {
+            using (var command = connection.CreateCommand())
+            {
+                command.CommandText = script;
+                command.ExecuteNonQuery();
+            }
+        }
+    }
+}

NHibernate.Tests/MappingWithTwoJoinsTests.cs

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+using System;
+using NUnit.Framework;
+using System.Linq;
+
+namespace NHibernate.Tests
+{
+    [TestFixture]
+    public class MappingWithTwoJoinsTests
+    {
+        [Test]
+        public void NHibernate_should_not_throw_when_querying_a_Person_mapped_using_MbC()
+        {
+            var sessionFactoryCreator = new SessionFactoryCreator();
+
+            using (var sessionFactory = sessionFactoryCreator.GetSessionFactoryWithMbcMappings())
+            using(var session = sessionFactory.OpenSession())
+            {
+                var initializer = new DbInitializer();
+                initializer.InitializeDatabase(session.Connection);
+
+                Assert.That(() => session.Query<Person>().FirstOrDefault(x => x.Name == "Jane Doe"), Throws.Nothing);
+            }
+        }
+
+        [Test]
+        public void NHibernate_should_not_throw_when_querying_a_Person_mapped_using_XML()
+        {
+            var sessionFactoryCreator = new SessionFactoryCreator();
+
+            using (var sessionFactory = sessionFactoryCreator.GetSessionFactoryWithXmlMappings())
+            using (var session = sessionFactory.OpenSession())
+            {
+                var initializer = new DbInitializer();
+                initializer.InitializeDatabase(session.Connection);
+
+                Assert.That(() => session.Query<Person>().FirstOrDefault(x => x.Name == "Jane Doe"), Throws.Nothing);
+            }
+        }
+    }
+}

NHibernate.Tests/NHibernate.Tests.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp2.2</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="NHibernate" Version="5.3.2" />
+    <PackageReference Include="NUnit" Version="3.12.0" />
+    <PackageReference Include="NUnit3TestAdapter" Version="3.16.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.5.0" />
+    <PackageReference Include="System.Data.SQLite.Core" Version="1.0.113.1" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Remove="Mappings\PersonMap.hbm.xml" />
+    <None Remove="CreateDb.sql" />
+    <None Remove="PersonMap.hbm.xml" />
+  </ItemGroup>
+  <ItemGroup>
+    <EmbeddedResource Include="CreateDb.sql" />
+    <EmbeddedResource Include="PersonMap.hbm.xml" />
+  </ItemGroup>
+</Project>

NHibernate.Tests/Person.cs

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+using System;
+namespace NHibernate.Tests
+{
+    public class Person
+    {
+        public virtual int PersonId { get; set; }
+
+        // Comes from the Person table
+        public virtual string Name { get; set; }
+
+        // Comes from the Address table
+        public virtual string City { get; set; }
+
+        // Comes from the PayrollInfo table
+        public virtual int PayrollNumber { get; set; }
+    }
+}

NHibernate.Tests/PersonMap.cs

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+using NHibernate.Mapping.ByCode.Conformist;
+
+namespace NHibernate.Tests
+{
+    public class PersonMap : ClassMapping<Person>
+    {
+        // Note that the XML mapping in the same directory as this is equivalent.
+        // Only one of the two mappings should be used at a time.
+
+        public PersonMap()
+        {
+            Id(x => x.PersonId);
+
+            Property(x => x.Name);
+
+            Join("PayrollInfo", j =>
+            {
+                j.Key(k => k.Column("PayrollInfoPersonId"));
+                j.Property(x => x.PayrollNumber);
+            });
+
+            Join("Address", j =>
+            {
+                j.Key(k => k.Column("AddressPersonId"));
+                j.Property(x => x.City);
+            });
+        }
+    }
+}

NHibernate.Tests/PersonMap.hbm.xml

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+<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
+                   namespace="NHibernate.Tests"
+                   assembly="NHibernate.Tests">
+
+    <!--
+        Note that the Mapping-by-Code mapping in the same directory as this is equivalent.
+        Only one of the two mappings should be used at a time.
+    -->
+
+    <class name="Person" table="Person">
+        <id name="PersonId" />
+        <property name="Name" />
+
+        <join table="PayrollInfo">
+            <key column="PayrollInfoPersonId" />
+            <property name="PayrollNumber" />
+        </join>
+
+        <join table="Address">
+            <key column="AddressPersonId" />
+            <property name="City" />
+        </join>
+    </class>
+
+</hibernate-mapping>

NHibernate.Tests/SessionFactoryCreator.cs

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+using System;
+using System.Reflection;
+using NHibernate.Cfg;
+using NHibernate.Mapping.ByCode;
+
+namespace NHibernate.Tests
+{
+    public class SessionFactoryCreator
+    {
+        public ISessionFactory GetSessionFactoryWithMbcMappings()
+        {
+            var config = GetConfigWithoutMappings();
+            AddMbcMappings(config);
+            return config.BuildSessionFactory();
+        }
+
+        public ISessionFactory GetSessionFactoryWithXmlMappings()
+        {
+            var config = GetConfigWithoutMappings();
+            AddXmlMappings(config);
+            return config.BuildSessionFactory();
+        }
+
+        Configuration GetConfigWithoutMappings()
+        {
+            var config = new Configuration();
+
+            // For simplicity of reproduction I'm using SQLite in-memory DB, but
+            // I have seen the same problem reproduced using MS-SQL 2012 as well, so
+            // I don't think that db/dialect is relevant.
+            config.DataBaseIntegration(db =>
+            {
+                db.Driver<Driver.SQLite20Driver>();
+                db.Dialect<Dialect.SQLiteDialect>();
+                db.ConnectionString = "Data Source=:memory:;Version=3;New=True;";
+            });
+
+            return config;
+        }
+
+        void AddMbcMappings(Configuration config)
+        {
+            var mapper = new ConventionModelMapper();
+            mapper.AddMapping<PersonMap>();
+            var mapping = mapper.CompileMappingForAllExplicitlyAddedEntities();
+
+            config.AddDeserializedMapping(mapping, "MbC-Mappings");
+        }
+
+        void AddXmlMappings(Configuration config)
+        {
+            config.AddAssembly(Assembly.GetExecutingAssembly());
+        }
+    }
+}

README.md

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+# Mapping-By-Code `Join` repro case
+This repository is a reproduction case for [a bug in NHibernate] whereby Mapping By Code (MbC) produces incorrect SQL if there is more than one `Join` in a single class mapping.  It would seem that parts of the join mapping from the first of the joins are accidentally overrwriting/overriding the same parts of the join mapping from subsequent joins in the same class mapping file.  More information may be found at the linked issue.
+
+The reproduction case framed as a pair of NUnit test cases, so to see the results just clone the repo and run **dotnet test**.
+
+* The test case `NHibernate_should_not_throw_when_querying_a_Person_mapped_using_XML` passes, and shows that NHibernate behaves correctly when not using MbC
+* The test case `NHibernate_should_not_throw_when_querying_a_Person_mapped_using_MbC` fails, demonstrating the bug
+
+Note that in this reproduction case, to make it as easy as possible to run, I have used an in-memory SQLite database.  I have also seen this same bug reproduced against MS-SQL server 2012, so I do not think that the database, driver or dialect are related to the problem.
+
+### What the tests do
+The test project sets up two instances of `ISessionFactory`, which *should theoretically be equivalent*.  One session factory uses MbC (see the class `PersonMap`) and the other session factory uses XML HBM mappings (see the file `PersonMap.hbm.xml`).
+
+A class named `DbInitializer` is used to create a sample database schema matching those mappings, with some sample data.  The tests then query this data using a Linq query.
+
+* In the case of the XML-based mappings, everything works OK and no exception is raised.
+
+* In the case of the MbC-based mappings, the query throws an exception, due to incorrect SQL being sent to the database driver.
+
+### The exception & SQL
+The exception raised from the MbC test case is an `NHibernate.Exceptions.GenericADOException`, wrapping  a native ADO exception from the database driver, complaining about invalid SQL logic.
+
+The SQL which is sent to the database (in the failing test) is as follows.  *I have made trivial whitespace changes for readability, as well as adding a comment to point out the error*.
+
+```sql
+select
+    person0_.PersonId           as personid1_0_,
+    person0_.Name               as name2_0_,
+    person0_1_.PayrollNumber    as payrollnumber2_1_,
+    person0_2_.City             as city2_2_
+
+from
+    Person person0_
+    inner join PayrollInfo person0_1_
+        on person0_.PersonId=person0_1_.AddressPersonId
+--                                      ^^^ This is the error, it is the wrong column name,
+--                                          it should be PayrollInfoPersonId
+    inner join Address person0_2_
+        on person0_.PersonId=person0_2_.AddressPersonId
+
+where person0_.Name=@p0
+
+limit 1
+```
+
+[a bug in NHibernate]: https://github.com/nhibernate/nhibernate-core/issues/1277