Fix rails db command with sqlite3 database

When using sqlite3 it was attempting to find the database file based on
Rails.root, the problem is that Rails.root is not always present because
we try to first manually load "config/database.yml" instead of loading
the entire app, to make "rails db" faster.

This means that when we're in the root path of the app, calling "rails db"
won't allow us to use Rails.root, making the command fail for sqlite3
with the error:

    ./rails/commands/dbconsole.rb:62:in `start':
      undefined method `root' for Rails:Module (NoMethodError)

The fix is to simply not pass any dir string to File.expand_path, which
will make it use the current directory of the process as base, or the
root path of the app, which is what we want.

When we are in any other subdirectory, calling "rails db" should work
just fine, because "config/database.yml" won't be found, thus "rails db"
will fallback to loading the app, making Rails.root available.

Closes #8257.

2 files changed, 13 insertions, 5 deletions

diff --git a/railties/lib/rails/commands/dbconsole.rb b/railties/lib/rails/commands/dbconsole.rb
index 90359d1c08..d614328e52 100644
--- a/railties/lib/rails/commands/dbconsole.rb
+++ b/railties/lib/rails/commands/dbconsole.rb
@@ -6,7 +6,7 @@ require 'rbconfig'
 module Rails
   class DBConsole
     attr_reader :config, :arguments
-    
+
     def self.start
       new.start
     end
@@ -59,7 +59,7 @@ module Rails
 
         args << "-#{options['mode']}" if options['mode']
         args << "-header" if options['header']
-        args << File.expand_path(config['database'], Rails.root)
+        args << File.expand_path(config['database'], Rails.respond_to?(:root) ? Rails.root : nil)
 
         find_cmd_and_exec('sqlite3', *args)
 
@@ -108,7 +108,7 @@ module Rails
 
     def parse_arguments(arguments)
       options = {}
-      
+
       OptionParser.new do |opt|
         opt.banner = "Usage: rails dbconsole [environment] [options]"
         opt.on("-p", "--include-password", "Automatically provide the password from database.yml") do |v|
@@ -123,7 +123,7 @@ module Rails
         opt.on("--header") do |h|
           options['header'] = h
         end
-        
+
         opt.on("-h", "--help", "Show this help message.") do
           puts opt
           exit
@@ -142,7 +142,7 @@ module Rails
         env = arguments.first
         options[:environment] = %w(production development test).detect {|e| e =~ /^#{env}/} || env
       end
-      
+
       options
     end
 
diff --git a/railties/test/commands/dbconsole_test.rb b/railties/test/commands/dbconsole_test.rb
index d45bdaabf5..6316584825 100644
--- a/railties/test/commands/dbconsole_test.rb
+++ b/railties/test/commands/dbconsole_test.rb
@@ -116,6 +116,14 @@ class Rails::DBConsoleTest < ActiveSupport::TestCase
     assert !aborted
   end
 
+  def test_sqlite3_db_without_defined_rails_root
+    Rails.stubs(:respond_to?)
+    Rails.expects(:respond_to?).with(:root).once.returns(false)
+    dbconsole.expects(:find_cmd_and_exec).with('sqlite3', Rails.root.join('../config/db.sqlite3').to_s)
+    start(adapter: 'sqlite3', database: 'config/db.sqlite3')
+    assert !aborted
+  end
+
   def test_oracle
     dbconsole.expects(:find_cmd_and_exec).with('sqlplus', 'user@db')
     start(adapter: 'oracle', database: 'db', username: 'user', password: 'secret')