Test case: Parsing meessage with duplicate keys

dist/pigeon/parser.rb

@@ -1,5 +1,7 @@
 module Pigeon
   class Parser
+    class DuplicateKeyError < StandardError; end
+
     def self.parse(tokens)
       self.new(tokens).parse
     end
@@ -37,7 +39,7 @@ module Pigeon
 
     def set(key, value, hash = @scratchpad)
       if hash[key]
-        raise "Double entry detected: #{key}"
+        raise DuplicateKeyError, "Found duplicate keys: #{key}"
       else
         hash[key] = value
       end

spec/pigeon/parser_spec.rb

@@ -9,6 +9,18 @@ RSpec.describe Pigeon::Lexer do
   let(:example_bundle) { File.read("./spec/fixtures/normal.bundle") }
   let(:tokens) { Pigeon::Lexer.tokenize(example_bundle) }
 
+  BAD_TOKENS = [
+    [:AUTHOR, "@DYdgK1KUInVtG3lS45hA1HZ-jTuvfLKsxDpXPFCve04=.ed25519"],
+    [:KIND, "invalid"],
+    [:PREV, "NONE"],
+    [:DEPTH, 0],
+    [:HEADER_END],
+    [:BODY_ENTRY, "duplicate", "Pigeon does not allow duplicate keys."],
+    [:BODY_ENTRY, "duplicate", "This key is a duplicate."],
+    [:SIGNATURE, "DN7yPTE-m433ND3jBL4oM23XGxBKafjq0Dp9ArBQa_TIGU7DmCxTumieuPBN-NKxlx_0N7-c5zjLb5XXVHYPCQ==.sig.ed25519"],
+    [:MESSAGE_END],
+  ]
+
   it "parses tokens" do
     results = Pigeon::Parser.parse(tokens)
     expect(results.length).to eq(2)
@@ -24,4 +36,9 @@ RSpec.describe Pigeon::Lexer do
     re_bundled = messages.map(&:render).join("\n\n") + "\n"
     expect(re_bundled).to eq(example_bundle)
   end
+
+  it "finds duplicate keys" do
+    error = Pigeon::Parser::DuplicateKeyError
+    expect { Pigeon::Parser.parse(BAD_TOKENS) }.to raise_error(error)
+  end
 end