Add specs for .encode

spec/lib/rex/encoder/nonalpha_spec.rb

@@ -140,4 +140,49 @@ describe Rex::Encoder::NonAlpha do
     end
   end
 
+  describe ".encode" do
+    subject { described_class.encode(buf) }
+
+    context "when buf includes a badchar" do
+      let(:buf) { "ABCDEF{" }
+
+      it "raises an error" do
+        expect { subject }.to raise_error(RuntimeError)
+      end
+    end
+
+    context "when buf includes Alpha chars" do
+      let(:buf) { "@#()" }
+
+      it "returns an String" do
+        is_expected.to be_an(String)
+      end
+
+      it "includes the decoder stub" do
+        is_expected.to match(decoder)
+      end
+
+      it "doesn't include the original buf" do
+        is_expected.to_not include(buf)
+      end
+    end
+
+    context "when buf doesn't include Alpha chars" do
+      let(:buf) { "ABCD" }
+
+      it "returns an String" do
+        is_expected.to be_an(String)
+      end
+
+      it "includes the decoder stub" do
+        is_expected.to match(decoder)
+      end
+
+      it "includes the original buf" do
+        is_expected.to include(buf)
+      end
+    end
+
+  end
+
 end