connection initialization: deep_dup the config

AR tests do things like:
  ActiveRecord::Base.configurations["arunit"].merge(database: "inexistent_activerecord_unittest")
which is also valid in applications. Not dup'ing the config is problematic:
E.g. the mysql adapter has this (simplified):

  unless config[:url]
    config[:url] = "...#{config[:database]}"
  end

So once a DB connection has been made with the original config, :url is
set, above example that tries a different DB has no effect at all and
gives a connection the the original database instead. Fun.

.deep_dup solves the problem as the original config is left untouched.

Author: dr-itz

lib/arjdbc/mysql/connection_methods.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 ArJdbc::ConnectionMethods.module_eval do
   def mysql_connection(config)
+    config = config.deep_dup
     # NOTE: this isn't "really" necessary but Rails (in tests) assumes being able to :
     #   ActiveRecord::Base.mysql2_connection ActiveRecord::Base.configurations['arunit'].merge(database: ...)
     config = symbolize_keys_if_necessary(config)

lib/arjdbc/postgresql/connection_methods.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 ArJdbc::ConnectionMethods.module_eval do
   def postgresql_connection(config)
+    config = config.deep_dup
     # NOTE: this isn't "really" necessary but Rails (in tests) assumes being able to :
     #   ActiveRecord::Base.postgresql_connection ActiveRecord::Base.configurations['arunit'].merge(:insert_returning => false)
     # ... while using symbols by default but than configurations returning string keys ;(

lib/arjdbc/sqlite3/connection_methods.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 ArJdbc::ConnectionMethods.module_eval do
   def sqlite3_connection(config)
+    config = config.deep_dup
     config[:adapter_spec] ||= ::ArJdbc::SQLite3
     config[:adapter_class] = ActiveRecord::ConnectionAdapters::SQLite3Adapter unless config.key?(:adapter_class)
 

test/db/mysql/unit_test.rb

@@ -96,7 +96,7 @@ def initialize; end
       connection_handler = connection_handler_stub
 
       config = { :jndi => 'jdbc/TestDS' }
-      connection_handler.expects(:jndi_connection)
+      connection_handler.expects(:jndi_connection).with() { |c| config = c }
       connection_handler.mysql_connection config
 
       # we do not complete username/database etc :
@@ -126,7 +126,7 @@ def initialize; end
       connection_handler = connection_handler_stub
 
       config = { database: 'MyDB' }
-      connection_handler.expects(:jdbc_connection)
+      connection_handler.expects(:jdbc_connection).with() { |c| config = c }
       ::Jdbc::MySQL.expects(:driver_name).returns('com.mysql.CustomDriver')
       connection_handler.mysql_connection config
       assert_equal 'com.mysql.CustomDriver', config[:driver]
@@ -138,7 +138,7 @@ def initialize; end
       connection_handler = connection_handler_stub
 
       config = { database: 'MyDB' }
-      connection_handler.expects(:jdbc_connection)
+      connection_handler.expects(:jdbc_connection).with() { |c| config = c }
       ::Jdbc::MySQL.expects(:driver_name).returns('com.mysql.cj.jdbc.Driver')
       connection_handler.mysql_connection config
       assert_equal 'com.mysql.cj.jdbc.Driver', config[:driver]
@@ -174,7 +174,7 @@ def teardown
       connection_handler = connection_handler_stub
 
       config = { host: '127.0.0.1', database: 'MyDB' }
-      connection_handler.expects(:jdbc_connection)
+      connection_handler.expects(:jdbc_connection).with() { |c| config = c }
       connection_handler.mysql_connection config
 
       # we do not complete username/database etc :
@@ -201,7 +201,7 @@ def teardown
       connection_handler = connection_handler_stub
 
       config = { database: 'MyDB', driver: false }
-      connection_handler.expects(:jdbc_connection)
+      connection_handler.expects(:jdbc_connection).with() { |c| config = c }
       connection_handler.expects(:require).never
       connection_handler.mysql_connection config
       assert_not config[:driver] # allow Java's service discovery mechanism (with connector/j 8.0)
@@ -211,7 +211,7 @@ def teardown
       connection_handler = connection_handler_stub
 
       config = { database: 'MyDB', driver: 'org.mariadb.jdbc.Driver' }
-      connection_handler.expects(:jdbc_connection)
+      connection_handler.expects(:jdbc_connection).with() { |c| config = c }
       connection_handler.mysql_connection config
 
       # we do not complete username/database etc :
@@ -224,4 +224,4 @@ def teardown
 
   end
 
-end if defined? JRUBY_VERSION
+end if defined? JRUBY_VERSION

test/db/postgresql/unit_test.rb

@@ -22,7 +22,7 @@ class PostgresUnitTest < Test::Unit::TestCase
       connection_handler = connection_handler_stub
 
       config = { :jndi => 'jdbc/TestDS' }
-      connection_handler.expects(:jndi_connection)
+      connection_handler.expects(:jndi_connection).with() { |c| config = c }
       connection_handler.postgresql_connection config
 
       # we do not complete username/database etc :