Add a basic python spec file

spec/lib/msf/core/payload/python_spec.rb

@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+RSpec.describe Msf::Payload::Python do
+  describe '#create_exec_stub' do
+    let(:python_code) { 'print("hello world");' }
+
+    it 'does not include double quotes' do
+      # some usages of this method make this assumption and breaking it would create problems
+      expect(described_class.create_exec_stub(python_code)).to_not include('"')
+    end
+
+    it 'does not include spaces' do
+      expect(described_class.create_exec_stub(python_code)).to_not include(' ')
+    end
+
+    it 'does not include semicolons' do
+      # this makes sure that the result is a single expression, not a series of statements
+      expect(described_class.create_exec_stub(python_code)).to_not include(';')
+    end
+  end
+end