make SQLite3::Database.open return the block result instead of the db…

… instance

To make it follow common pattern, like for File:

    result = File.open('/dev/zero') do |f|
      f.read(10)
    end

See discussion in #414

lib/sqlite3/database.rb

@@ -39,7 +39,22 @@ class Database
 
     class << self
 
-      alias :open :new
+      # Without block works exactly as new.
+      # With block, like new closes the database at the end, but unlike new
+      # returns the result of the block instead of the database instance.
+      def open( *args )
+        database = new(*args)
+
+        if block_given?
+          begin
+            yield database
+          ensure
+            database.close
+          end
+        else
+          database
+        end
+      end
 
       # Quotes the given string, making it safe to use in an SQL statement.
       # It replaces all instances of the single-quote character with two

test/test_database.rb

@@ -198,11 +198,25 @@ def test_execute_batch2
 
     def test_new
       db = SQLite3::Database.new(':memory:')
-      assert db
+      assert_instance_of(SQLite3::Database, db)
     ensure
       db.close if db
     end
 
+    def test_open
+      db = SQLite3::Database.open(':memory:')
+      assert_instance_of(SQLite3::Database, db)
+    ensure
+      db.close if db
+    end
+
+    def test_open_returns_block_result
+      result = SQLite3::Database.open(':memory:') do |db|
+        :foo
+      end
+      assert_equal :foo, result
+    end
+
     def test_new_yields_self
       thing = nil
       SQLite3::Database.new(':memory:') do |db|
@@ -211,6 +225,14 @@ def test_new_yields_self
       assert_instance_of(SQLite3::Database, thing)
     end
 
+    def test_open_yields_self
+      thing = nil
+      SQLite3::Database.open(':memory:') do |db|
+        thing = db
+      end
+      assert_instance_of(SQLite3::Database, thing)
+    end
+
     def test_new_with_options
       # determine if Ruby is running on Big Endian platform
       utf16 = ([1].pack("I") == [1].pack("N")) ? "UTF-16BE" : "UTF-16LE"
@@ -221,7 +243,7 @@ def test_new_with_options
         db = SQLite3::Database.new(Iconv.conv(utf16, 'UTF-8', ':memory:'),
                                    :utf16 => true)
       end
-      assert db
+      assert_instance_of(SQLite3::Database, db)
     ensure
       db.close if db
     end
@@ -241,6 +263,15 @@ def test_block_closes_self
       assert thing.closed?
     end
 
+    def test_open_with_block_closes_self
+      thing = nil
+      SQLite3::Database.open(':memory:') do |db|
+        thing = db
+        assert !thing.closed?
+      end
+      assert thing.closed?
+    end
+
     def test_block_closes_self_even_raised
       thing = nil
       begin
@@ -253,6 +284,18 @@ def test_block_closes_self_even_raised
       assert thing.closed?
     end
 
+    def test_open_with_block_closes_self_even_raised
+      thing = nil
+      begin
+        SQLite3::Database.open(':memory:') do |db|
+          thing = db
+          raise
+        end
+      rescue
+      end
+      assert thing.closed?
+    end
+
     def test_prepare
       db = SQLite3::Database.new(':memory:')
       stmt = db.prepare('select "hello world"')