Add `DBShell::DatabaseClient`

A more generic interface to specific database adapter clients. This
class will act as a frontend to the others.

Calling its `.runshell()` will call the appropriate `.runshell()` for
the adapter provided in `connection_params`.

This way, we have a single entry point to start a database shell from
the Rake `dbshell` task.

2 files changed, 41 insertions, 0 deletions

diff --git a/lib/dbshell/database_client.rb b/lib/dbshell/database_client.rb
new file mode 100644
index 0000000..8d55095
--- /dev/null
+++ b/lib/dbshell/database_client.rb
@@ -0,0 +1,15 @@
+class DBShell::DatabaseClient
+  def self.handler(connection_params)
+    case connection_params['adapter']
+    when 'sqlite3'
+      DBShell::Sqlite3Client
+    when 'postgresql'
+      DBShell::PostgresClient
+    else
+      raise DBShell::InvalidDatabaseAdapter
+    end
+  end
+end
+
+
+class DBShell::InvalidDatabaseAdapter < StandardError; end
diff --git a/spec/dbshell/database_client_spec.rb b/spec/dbshell/database_client_spec.rb
new file mode 100644
index 0000000..1659fa3
--- /dev/null
+++ b/spec/dbshell/database_client_spec.rb
@@ -0,0 +1,26 @@
+require 'minitest/autorun'
+require 'dbshell/database_client'
+
+describe DBShell::DatabaseClient do
+  describe ".handler" do
+    it "handles SQLite3" do
+      DBShell::DatabaseClient.handler({
+        'adapter' => 'sqlite3'
+      }).must_equal(DBShell::Sqlite3Client)
+    end
+
+    it "handles Postgres" do
+      DBShell::DatabaseClient.handler({
+        'adapter' => 'postgresql'
+      }).must_equal(DBShell::PostgresClient)
+    end
+
+    it "raises an error if no suitable adapter is found" do
+      proc do
+        DBShell::DatabaseClient.handler({
+          'adapter' => 'sybil_system'
+        })
+      end.must_raise(DBShell::InvalidDatabaseAdapter)
+    end
+  end
+end