Remove unused variables

Usage of `adapter` variable was removed in: b39c8c9

spec/database_cleaner/active_record/truncation/mysql2_spec.rb

@@ -6,10 +6,9 @@ require 'database_cleaner/active_record/truncation/shared_fast_truncation'
 
 module ActiveRecord
   module ConnectionAdapters
-    describe do 
+    describe do
       before(:all) { active_record_mysql2_setup }
 
-      let(:adapter) { Mysql2Adapter }
       let(:connection) { active_record_mysql2_connection }
 
       describe "#truncate_table" do
@@ -31,7 +30,6 @@ module ActiveRecord
       end
 
       it_behaves_like "an adapter with pre-count truncation" do
-        let(:adapter) { Mysql2Adapter }
         let(:connection) { active_record_mysql2_connection }
       end
     end

spec/database_cleaner/active_record/truncation/mysql_spec.rb

@@ -6,10 +6,9 @@ require 'database_cleaner/active_record/truncation/shared_fast_truncation'
 
 module ActiveRecord
   module ConnectionAdapters
-    describe do 
+    describe do
       before(:all) { active_record_mysql_setup }
 
-      let(:adapter) { MysqlAdapter }
       let(:connection) { active_record_mysql_connection }
 
       describe "#truncate_table" do
@@ -29,9 +28,8 @@ module ActiveRecord
           User.create.id.should eq 1
         end
       end
- 
+
       it_behaves_like "an adapter with pre-count truncation" do
-        let(:adapter) { MysqlAdapter }
         let(:connection) { active_record_mysql_connection }
       end
     end

spec/database_cleaner/active_record/truncation/postgresql_spec.rb

@@ -9,8 +9,6 @@ module ActiveRecord
     describe do
       before(:all) { active_record_pg_setup }
 
-      let(:adapter) { PostgreSQLAdapter }
-
       let(:connection) do
         active_record_pg_connection
       end
@@ -38,7 +36,6 @@ module ActiveRecord
       end
 
       it_behaves_like "an adapter with pre-count truncation" do
-        let(:adapter) { PostgreSQLAdapter }
         let(:connection) { active_record_pg_connection }
       end
 

spec/database_cleaner/active_record/truncation/sqlite3_spec.rb

@@ -8,8 +8,6 @@ module ActiveRecord
     describe do
       before(:all) { active_record_sqlite3_setup }
 
-      let(:adapter) { SQLite3Adapter }
-
       let(:connection) do
         active_record_sqlite3_connection
       end