diff --git a/spec/defines/iface_spec.rb b/spec/defines/iface_spec.rb
new file mode 100644
index 0000000..38b9852
--- /dev/null
+++ b/spec/defines/iface_spec.rb
@@ -0,0 +1,49 @@
+require 'spec_helper'
+
+describe 'debnet::iface' do
+  let(:title) { 'eth0' }
+  let(:facts) {{
+    :concat_basedir => '/var/lib/puppet/concat',
+    :osfamily => 'Debian',
+  }}
+
+  context "Non-Debian system" do
+    let(:facts) {{
+      :osfamily => 'RedHat',
+    }}
+    it {
+      expect { should raise_error(Puppet::Error) }
+    }
+  end
+
+  context 'eth0 with address and mask' do
+    let(:params) {{
+      :method  => 'static',
+      :address => '192.168.254.253',
+      :netmask => '24',
+    }}
+    it {
+      should contain_concat('/etc/network/interfaces').with({
+        'owner'          => 'root',
+        'group'          => 'root',
+        'mode'           => '0644',
+        'ensure_newline' => true,
+        'order'          => 'numeric',
+      })
+      should contain_concat__fragment('/etc/network/interfaces').with({
+        'target' => '/etc/network/interfaces',
+        'order'  => '10',
+      })
+      should contain_concat__fragment('/etc/network/interfaces') \
+        .with_content(/controlled by Puppet module trepasi-debnet/)
+      should contain_concat__fragment('eth0_stanza').with({
+        'target' => '/etc/network/interfaces',
+      })
+      should contain_concat__fragment('eth0_stanza') \
+        .with_content(/^# interface eth0 configuration/)
+      should contain_concat__fragment('eth0_stanza') \
+        .with_content(/^iface eth0 inet static/)
+    }
+  end
+
+end