Try to add support for shell aliases through Ruby's `Kernel.exec`add-support-for-shell-aliased-database-commands

Work in progress.

Ruby's `system` and `exec` don't load shell aliases, so the executables
defined in `EXECUTABLE_NAME` will always be the ones used to launch
database shells.

The trouble is, users might have installed the command with a different
name (as in "mysql5"), or they might not have the command on their path
(as in my case when using Postgres.app).

Apparently you can use an interactive or login shell to get aliases
(using the `-l` or `-i` flags, which do slightly different things,
sourcing .profile and .bashrc separately). Here's what I was following:

http://stackoverflow.com/questions/12060863/python-subprocess-call-a-bash-alias/25099813#25099813

Unfortunately I haven't been able to get it to work. Dropping this for
now.

3 files changed, 39 insertions, 1 deletions

diff --git a/lib/dbshell/client/postgres.rb b/lib/dbshell/client/postgres.rb
index 78b82d7..9979710 100644
--- a/lib/dbshell/client/postgres.rb
+++ b/lib/dbshell/client/postgres.rb
@@ -1,3 +1,5 @@
+require 'dbshell/exec_alias'
+
 module DBShell
   module Client
     class Postgres
@@ -5,7 +7,7 @@ module DBShell
 
       def self.runshell(db_info)
         args = self.build_command(db_info)
-        exec(*args)
+        DBShell::ExecAlias.exec(args)
       end
 
       def self.build_command(db_info)
diff --git a/lib/dbshell/exec_alias.rb b/lib/dbshell/exec_alias.rb
new file mode 100644
index 0000000..7bd86b7
--- /dev/null
+++ b/lib/dbshell/exec_alias.rb
@@ -0,0 +1,11 @@
+module DBShell
+  class ExecAlias
+    def self.exec(command_args)
+      Kernel.exec(*self.build_command(command_args))
+    end
+
+    def self.build_command(command_args)
+      [ENV['SHELL'], '--login', '-c', command_args.join(' ')]
+    end
+  end
+end
diff --git a/spec/dbshell/exec_alias_spec.rb b/spec/dbshell/exec_alias_spec.rb
new file mode 100644
index 0000000..1b8c425
--- /dev/null
+++ b/spec/dbshell/exec_alias_spec.rb
@@ -0,0 +1,25 @@
+require 'minitest/autorun'
+require 'dbshell/exec_alias'
+
+describe DBShell::ExecAlias do
+  describe ".build_command" do
+    it "prefixes the command with an interactive version of the current \
+        shell" do
+      DBShell::ExecAlias.build_command([
+        'psql',
+        '-U',
+        'derpyhooves',
+        '-h',
+        'mailmarehost',
+        '-p',
+        '6027',
+        'dbname'
+      ]).must_equal([
+        ENV['SHELL'],
+        '-i',
+        '-c',
+        'psql -U derpyhooves -h mailmarehost -p 6027 dbname'
+      ])
+    end
+  end
+end