diff --git a/ci/postgresql/pom.xml b/ci/postgresql/pom.xml
index 2b6c9632f..4c0451870 100644
--- a/ci/postgresql/pom.xml
+++ b/ci/postgresql/pom.xml
@@ -12,7 +12,7 @@
         <dependency>
             <groupId>org.postgresql</groupId>
             <artifactId>postgresql</artifactId>
-            <version>42.2.19</version>
+            <version>42.5.0</version>
         </dependency>
         <dependency>
             <groupId>org.slf4j</groupId>
diff --git a/spec/integration/drivers/bigquery_client_test.rb b/spec/integration/drivers/bigquery_client_test.rb
new file mode 100644
index 000000000..55914747a
--- /dev/null
+++ b/spec/integration/drivers/bigquery_client_test.rb
@@ -0,0 +1,69 @@
+require 'spec_helper'
+require 'gooddata/cloud_resources/bigquery/bigquery_client'
+require 'rspec'
+require 'csv'
+require 'benchmark'
+
+describe GoodData::CloudResources::BigQueryClient do
+  before do
+    @project = ENV['BIGQUERY_PROJECT_ID'] || 'test-project'
+    @schema = ENV['BIGQUERY_SCHEMA'] || 'public'
+    @client_email = ENV['BIGQUERY_CLIENT_EMAIL'] || 'test-client-email'
+    @private_key = ENV['BIGQUERY_PRIVATE_KEY'] || 'test-private-key'
+  end
+
+  let(:valid_options) do
+    {
+      'bigquery_client' => {
+        'connection' => {
+          'project' => @project,
+          'schema' => @schema,
+          'authentication' => {
+            'serviceAccount' => {
+              'clientEmail' => @client_email,
+              'privateKey' => @private_key
+            }
+          }
+        }
+      }
+    }
+  end
+
+  describe '.accept?' do
+    it 'returns true for bigquery type' do
+      expect(GoodData::CloudResources::BigQueryClient.accept?('bigquery')).to be true
+    end
+
+    it 'returns false for other types' do
+      expect(GoodData::CloudResources::BigQueryClient.accept?('mysql')).to be false
+    end
+  end
+
+  describe '#initialize' do
+    it 'raises an error if bigquery_client is missing' do
+      expect { GoodData::CloudResources::BigQueryClient.new({}) }.to raise_error(RuntimeError, "Data Source needs a client to BigQuery to be able to query the storage but 'bigquery_client' is empty.")
+    end
+
+    it 'initializes with valid options' do
+      client = GoodData::CloudResources::BigQueryClient.new(valid_options)
+      expect(client).to be_an_instance_of(GoodData::CloudResources::BigQueryClient)
+    end
+  end
+
+  describe '#create_client' do
+    it 'creates a BigQuery client' do
+      client = GoodData::CloudResources::BigQueryClient.new(valid_options)
+      bigquery_client = client.send(:create_client)
+      expect(bigquery_client).to be_a(Java::ComGoogleCloudBigquery::BigQuery)
+    end
+  end
+
+  describe '#realize_query' do
+    it 'executes a query and returns a CSV filename' do
+      client = GoodData::CloudResources::BigQueryClient.new(valid_options)
+      output_file = client.realize_query('select 50 + 50 as SUM', nil)
+      expect(File.read(output_file)).to include('100')
+      File.delete(output_file)
+    end
+  end
+end
diff --git a/spec/integration/drivers/mssql_client_test.rb b/spec/integration/drivers/mssql_client_test.rb
new file mode 100644
index 000000000..ec080d135
--- /dev/null
+++ b/spec/integration/drivers/mssql_client_test.rb
@@ -0,0 +1,70 @@
+require 'spec_helper'
+require 'gooddata/cloud_resources/mssql/mssql_client'
+require 'rspec'
+
+describe GoodData::CloudResources::MSSQLClient do
+  before do
+    @mssql_host = ENV['MSSQL_HOST'] || 'localhost'
+    @mssql_port = ENV['MSSQL_PORT'] || 1433
+    @mssql_database = ENV['MSSQL_DB'] || 'master'
+    @mssql_user = ENV['MSSQL_USER'] || 'sa'
+    @mssql_password = ENV['MSSQL_PASSWORD'] || 'Password123'
+  end
+
+  let(:valid_options) do
+    {
+      'mssql_client' => {
+        'connection' => {
+          'database' => @mssql_database,
+          'schema' => 'dbo',
+          'authentication' => {
+            'basic' => {
+              'userName' => @mssql_user,
+              'password' => @mssql_password
+            }
+          },
+          'sslMode' => 'prefer',
+          'url' => "jdbc:sqlserver://#{@mssql_host}:#{@mssql_port}"
+        }
+      }
+    }
+  end
+
+  describe '.accept?' do
+    it 'returns true for mssql type' do
+      expect(GoodData::CloudResources::MSSQLClient.accept?('mssql')).to be true
+    end
+
+    it 'returns false for other types' do
+      expect(GoodData::CloudResources::MSSQLClient.accept?('mysql')). to be false
+    end
+  end
+
+  describe '#build_connection_string' do
+    it 'builds a valid connection string' do
+      client = GoodData::CloudResources::MSSQLClient.new(valid_options)
+      connection_string = client.send(:build_connection_string)
+      expect(connection_string).to eq("jdbc:sqlserver://#{@mssql_host}:#{@mssql_port};database=#{@mssql_database};"\
+                                      "encrypt=false;trustServerCertificate=false;loginTimeout=30;")
+    end
+  end
+
+  describe '#initialize' do
+    it 'raises an error if mssql_client is missing' do
+      expect { GoodData::CloudResources::MSSQLClient.new({}) }.to raise_error(RuntimeError, "Data Source needs a client to MSSQL to be able to query the storage but 'mssql_client' is empty.")
+    end
+
+    it 'initializes with valid options' do
+      client = GoodData::CloudResources::MSSQLClient.new(valid_options)
+      expect(client).to be_an_instance_of(GoodData::CloudResources::MSSQLClient)
+    end
+
+    it 'connects to SQL Server and selects the version' do
+      client = GoodData::CloudResources::MSSQLClient.new(valid_options)
+      version_csv = client.realize_query('SELECT @@VERSION', nil)
+      expect(File).to exist(version_csv)
+      expect(File.read(version_csv)).to include('Microsoft SQL Server')
+      File.delete(version_csv)
+    end
+  end
+end
diff --git a/spec/integration/drivers/mysql_client_test.rb b/spec/integration/drivers/mysql_client_test.rb
new file mode 100644
index 000000000..544c69241
--- /dev/null
+++ b/spec/integration/drivers/mysql_client_test.rb
@@ -0,0 +1,141 @@
+# /Users/milandufek/dev/gooddata/gooddata-ruby/spec/integration/drivers/mysql_client_test.rb
+
+require 'spec_helper'
+require 'gooddata/cloud_resources/mysql/mysql_client'
+require 'rspec'
+require 'csv'
+require 'benchmark'
+
+describe GoodData::CloudResources::MysqlClient do
+  before do
+    @mysql_host = ENV['MYSQL_HOST'] || 'localhost'
+    @mysql_port = ENV['MYSQL_PORT'] || 3306
+    @mysql_database = ENV['MYSQL_DB'] || 'mysql'
+    @mysql_user = ENV['MYSQL_USER'] || 'root'
+    @mysql_password = ENV['MYSQL_SECRET'] || 'root'
+  end
+
+  let(:valid_options) do
+    {
+      'mysql_client' => {
+        'connection' => {
+          'database' => @mysql_database,
+          'schema' => 'public',
+          'authentication' => {
+            'basic' => {
+              'userName' => @mysql_user,
+              'password' => @mysql_password
+            }
+          },
+          'sslMode' => 'prefer',
+          'url' => "jdbc:mysql://#{@mysql_host}:#{@mysql_port}/#{@mysql_database}"
+        }
+      }
+    }
+  end
+
+  describe '.accept?' do
+    it 'returns true for mysql type' do
+      expect(GoodData::CloudResources::MysqlClient.accept?('mysql')).to be true
+    end
+
+    it 'returns false for other types' do
+      expect(GoodData::CloudResources::MysqlClient.accept?('postgresql')).to be false
+    end
+  end
+
+  describe '#initialize' do
+    it 'raises an error if mysql_client is missing' do
+      options = {}
+      expect { GoodData::CloudResources::MysqlClient.new(options) }.to raise_error(RuntimeError, "Data Source needs a client to Mysql to be able to query the storage but 'mysql_client' is empty.")
+    end
+
+    it 'raises an error if connection info is missing' do
+      options = { 'mysql_client' => {} }
+      expect { GoodData::CloudResources::MysqlClient.new(options) }.to raise_error(RuntimeError, 'Missing connection info for Mysql client')
+    end
+
+    it 'raises an error if sslMode is invalid' do
+      invalid_options = valid_options.dup
+      invalid_options['mysql_client']['connection']['sslMode'] = 'invalid'
+      expect { GoodData::CloudResources::MysqlClient.new(invalid_options) }.to raise_error(RuntimeError, 'SSL Mode should be prefer, require and verify-full')
+    end
+
+    it 'initializes with valid options' do
+      client = GoodData::CloudResources::MysqlClient.new(valid_options)
+      expect(client).not_to be_nil
+    end
+  end
+
+  describe '#build_url' do
+    it 'builds the correct URL' do
+      client = GoodData::CloudResources::MysqlClient.new(valid_options)
+      expected_url = "jdbc:mysql://#{@mysql_host}:#{@mysql_port}/#{@mysql_database}?&useSSL=true&requireSSL=false&verifyServerCertificate=false&useCursorFetch=true&enabledTLSProtocols=TLSv1.2"
+      expect(client.send(:build_url, "jdbc:mysql://#{@mysql_host}:#{@mysql_port}")).to eq(expected_url)
+    end
+  end
+
+  describe '#connect' do
+    it 'sets up the connection' do
+      client = GoodData::CloudResources::MysqlClient.new(valid_options)
+      client.connect
+      expect(client.instance_variable_get(:@connection)).not_to be_nil
+    end
+  end
+
+  describe '#realize_query' do
+    it 'executes the query and writes results to a CSV file' do
+      client = GoodData::CloudResources::MysqlClient.new(valid_options)
+      client.connect
+      output_file = client.realize_query('SELECT 123;', {})
+      expect(File).to exist(output_file)
+      expect(File.read(output_file)).to include('123')
+      File.delete(output_file)
+    end
+  end
+
+  describe '#fetch_size' do
+    it 'returns the correct fetch size for MySQL' do
+      client = GoodData::CloudResources::MysqlClient.new(valid_options)
+      expect(client.fetch_size).to eq(GoodData::CloudResources::MysqlClient::MYSQL_FETCH_SIZE)
+    end
+
+    it 'returns the correct fetch size for MongoDB BI Connector' do
+      mongo_options = valid_options.dup
+      mongo_options['mysql_client']['connection']['databaseType'] = GoodData::CloudResources::MysqlClient::MONGO_BI_TYPE
+      client = GoodData::CloudResources::MysqlClient.new(mongo_options)
+      expect(client.fetch_size).to eq(GoodData::CloudResources::MysqlClient::MONGO_BI_FETCH_SIZE)
+    end
+  end
+
+  describe '#get_ssl_mode' do
+    it 'returns the correct SSL mode for prefer' do
+      client = GoodData::CloudResources::MysqlClient.new(valid_options)
+      expect(client.send(:get_ssl_mode, 'prefer')).to eq(GoodData::CloudResources::MysqlClient::PREFER)
+    end
+
+    it 'returns the correct SSL mode for require' do
+      client = GoodData::CloudResources::MysqlClient.new(valid_options)
+      expect(client.send(:get_ssl_mode, 'require')).to eq(GoodData::CloudResources::MysqlClient::REQUIRE)
+    end
+
+    it 'returns the correct SSL mode for verify-full' do
+      client = GoodData::CloudResources::MysqlClient.new(valid_options)
+      expect(client.send(:get_ssl_mode, 'verify-full')).to eq(GoodData::CloudResources::MysqlClient::VERIFY_FULL)
+    end
+  end
+
+  describe '#add_extended' do
+    it 'returns the correct extended parameters for MongoDB BI Connector' do
+      mongo_options = valid_options.dup
+      mongo_options['mysql_client']['connection']['databaseType'] = GoodData::CloudResources::MysqlClient::MONGO_BI_TYPE
+      client = GoodData::CloudResources::MysqlClient.new(mongo_options)
+      expect(client.send(:add_extended)).to eq('&authenticationPlugins=org.mongodb.mongosql.auth.plugin.MongoSqlAuthenticationPlugin&useLocalTransactionState=true')
+    end
+
+    it 'returns an empty string for MySQL' do
+      client = GoodData::CloudResources::MysqlClient.new(valid_options)
+      expect(client.send(:add_extended)).to eq('')
+    end
+  end
+end
diff --git a/spec/integration/drivers/postgresql_client_test.rb b/spec/integration/drivers/postgresql_client_test.rb
new file mode 100644
index 000000000..7d1a65740
--- /dev/null
+++ b/spec/integration/drivers/postgresql_client_test.rb
@@ -0,0 +1,97 @@
+# spec/lib/gooddata/cloud_resources/postgresql/postgresql_client_spec.rb
+
+require 'spec_helper'
+require 'gooddata/cloud_resources/postgresql/postgresql_client'
+require 'rspec'
+require 'csv'
+require 'benchmark'
+
+describe GoodData::CloudResources::PostgresClient do
+  before do
+    @postresql_host = ENV['POSTGRES_HOST'] || 'localhost'
+    @postresql_port = ENV['POSTGRES_PORT'] || 5432
+    @postresql_database = ENV['POSTGRES_DB'] || 'postgres'
+    @postgres_schema = ENV['POSTGRES_SCHEMA'] || 'public'
+    @postresql_user = ENV['POSTGRES_USER'] || 'postgres'
+    @postresql_password = ENV['POSTGRES_SECRET'] || 'postgres'
+  end
+
+  let(:valid_options) do
+    {
+      'postgresql_client' => {
+        'connection' => {
+          'database' => @postresql_database,
+          'schema' => @postgres_schema,
+          'authentication' => {
+            'basic' => {
+              'userName' => @postresql_user,
+              'password' => @postresql_password
+            }
+          },
+          'sslMode' => 'prefer',
+          'url' => "jdbc:postgresql://#{@postresql_host}:#{@postresql_port}/#{@postresql_database}"
+        }
+      }
+    }
+  end
+
+  describe '.accept?' do
+    it 'returns true for postgresql type' do
+      expect(GoodData::CloudResources::PostgresClient.accept?('postgresql')).to be true
+    end
+
+    it 'returns false for other types' do
+      expect(GoodData::CloudResources::PostgresClient.accept?('mysql')).to be false
+    end
+  end
+
+  describe '#initialize' do
+    it 'raises an error if postgresql_client is missing' do
+      options = {}
+      expect { GoodData::CloudResources::PostgresClient.new(options) }.to raise_error(RuntimeError, "Data Source needs a client to Postgres to be able to query the storage but 'postgresql_client' is empty.")
+    end
+
+    it 'raises an error if connection info is missing' do
+      options = { 'postgresql_client' => {} }
+      expect { GoodData::CloudResources::PostgresClient.new(options) }.to raise_error(RuntimeError, 'Missing connection info for Postgres client')
+    end
+
+    it 'raises an error if sslMode is invalid' do
+      invalid_options = valid_options.dup
+      invalid_options['postgresql_client']['connection']['sslMode'] = 'invalid'
+      expect { GoodData::CloudResources::PostgresClient.new(invalid_options) }.to raise_error(RuntimeError, 'SSL Mode should be prefer, require and verify-full')
+    end
+
+    it 'initializes with valid options' do
+      client = GoodData::CloudResources::PostgresClient.new(valid_options)
+      expect(client).not_to be_nil
+    end
+  end
+
+  describe '#build_url' do
+    it 'builds the correct URL' do
+      client = GoodData::CloudResources::PostgresClient.new(valid_options)
+      expected_url = "jdbc:postgresql://#{@postresql_host}:#{@postresql_port}/#{@postresql_database}?sslmode=prefer"
+      expect(client.send(:build_url, "jdbc:postgresql://#{@postresql_host}:#{@postresql_port}")).to eq(expected_url)
+    end
+  end
+
+  describe '#connect' do
+    it 'sets up the connection' do
+      client = GoodData::CloudResources::PostgresClient.new(valid_options)
+      client.connect
+      expect(client.instance_variable_get(:@connection)).not_to be_nil
+    end
+  end
+
+  describe '#realize_query_version' do
+    it 'executes the query with postgres version and writes results to a CSV file' do
+      client = GoodData::CloudResources::PostgresClient.new(valid_options)
+      client.connect
+      output_file = client.realize_query('SELECT version();', {})
+      expect(File).to exist(output_file)
+      expect(File.read(output_file)).to include('PostgreSQL')
+      File.delete(output_file)
+    end
+  end
+end