Support diacrities for underscore

lib/dry/inflector.rb

@@ -283,8 +283,8 @@ def underscore(input)
         m2 = Regexp.last_match(2)
         "#{m1 ? "_" : ""}#{m2.downcase}"
       end
-      input.gsub!(/([A-Z\d]+)([A-Z][a-z])/, '\1_\2')
-      input.gsub!(/([a-z\d])([A-Z])/, '\1_\2')
+      input.gsub!(/([[:upper:][:digit:]]+)([[:upper:]][[:lower:]])/, '\1_\2')
+      input.gsub!(/([[:lower:][:digit:]])([[:upper:]])/, '\1_\2')
       input.tr!("-", "_")
       input.downcase!
       input

spec/unit/dry/inflector/underscore_spec.rb

@@ -34,6 +34,10 @@
       expect(subject.underscore(i("CLIRunner"))).to eq("cli_runner")
     end
 
+    it "underscores aCli as a_cli" do
+      expect(subject.underscore(i("aCLI"))).to eq("a_cli")
+    end
+
     it "accepts symbols" do
       expect(subject.underscore(:DataMapper)).to eq("data_mapper")
     end
@@ -44,5 +48,41 @@
       expect(subject.underscore(i("OpenSSL::HMAC"))).to eql("openssl/hmac")
       expect(subject.underscore(i("OpenSSL::Digest"))).to eql("openssl/digest")
     end
+
+    it "handles diacritics" do
+      expect(subject.underscore(i("éclairFest"))).to eql("éclair_fest")
+      expect(subject.underscore(i("éuaTrip"))).to eql("éua_trip")
+      expect(subject.underscore(i("festival-des-éclairs"))).to eql("festival_des_éclairs")
+      expect(subject.underscore(i("ÉBellisimo"))).to eql("é_bellisimo")
+      expect(subject.underscore(i("éBellisimo"))).to eql("é_bellisimo")
+    end
+
+    it "handles number followed by uppercase letter" do
+      expect(subject.underscore(i("9Lives"))).to eql("9_lives")
+    end
+
+    pending "handles number followed by lowercase letter" do
+      pending "this should be `7_ate_9`"
+      expect(subject.underscore(i("7Ate9"))).to eql("7_ate_9")
+    end
+
+    it "handles number followed by lowercase letter" do
+      pending "this should be 9_lives"
+      expect(subject.underscore(i("9lives"))).to eql("9_lives")
+    end
+
+    it "handle leading diacritic" do
+      expect(subject.underscore(i("éBellisimo"))).to eql("é_bellisimo")
+    end
+
+    it "handles leading number " do
+      pending "this should be 1_is_one"
+      expect(subject.underscore(i("1isOne"))).to eql("1_is_one")
+    end
+
+    it "handles leading number with diacritic" do
+      pending "this should be 1_é_bellisimo"
+      expect(subject.underscore(i("1éBellisimo"))).to eql("1_é_bellisimo")
+    end
   end
 end