Add validation warning if a translation contains Python only placeholders (fixes #287)

lib/twine/placeholders.rb

@@ -72,5 +72,11 @@ module Twine
     def convert_placeholders_from_flash_to_twine(input)
       input.gsub /\{\d+\}/, '%@'
     end
+
+    # Python supports placeholders in the form of `%(amount)03d`
+    # see https://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting
+    def contains_python_specific_placeholder(input)
+      /%\([a-zA-Z0-9_-]+\)#{PLACEHOLDER_PARAMETER_FLAGS_WIDTH_PRECISION_LENGTH}#{PLACEHOLDER_TYPES}/.match(input) != nil
+    end
   end
 end

lib/twine/runner.rb

@@ -241,6 +241,7 @@ module Twine
       duplicate_keys = Set.new
       keys_without_tags = Set.new
       invalid_keys = Set.new
+      keys_with_python_only_placeholders = Set.new
       valid_key_regex = /^[A-Za-z0-9_]+$/
 
       @twine_file.sections.each do |section|
@@ -253,6 +254,8 @@ module Twine
           keys_without_tags.add(definition.key) if definition.tags == nil or definition.tags.length == 0
 
           invalid_keys << definition.key unless definition.key =~ valid_key_regex
+
+          keys_with_python_only_placeholders << definition.key if definition.translations.values.any? { |v| Placeholders.contains_python_specific_placeholder(v) }
         end
       end
 
@@ -275,6 +278,10 @@ module Twine
         errors << "Found key(s) with invalid characters:\n#{join_keys.call(invalid_keys)}"
       end
 
+      unless keys_with_python_only_placeholders.empty?
+        errors << "Found key(s) with placeholders that are only supported by Python:\n#{join_keys.call(keys_with_python_only_placeholders)}"
+      end
+
       raise Twine::Error.new errors.join("\n\n") unless errors.empty?
 
       Twine::stdout.puts "#{@options[:twine_file]} is valid."

test/test_placeholders.rb

@@ -122,4 +122,21 @@ class PlaceholderTest < TwineTest
       assert_equal "some %@ more %@ text %@", from_flash("some {0} more {1} text {2}")
     end
   end
+
+  class PythonPlaceholder < PlaceholderTest
+    def test_negative_for_regular_placeholders
+      assert_equal false, Twine::Placeholders.contains_python_specific_placeholder(placeholder)
+    end
+
+    def test_positive_for_named_placeholders
+      inputs = [
+        "%(language)s has",
+        "For %(number)03d quotes",
+        "bought on %(app_name)s"
+      ]
+      inputs.each do |input|
+        assert_equal true, Twine::Placeholders.contains_python_specific_placeholder(input)
+      end
+    end
+  end
 end

test/test_validate_twine_file.rb

@@ -58,4 +58,12 @@ class TestValidateTwineFile < CommandTest
       Twine::Runner.new(@options.merge(pedantic: true), @twine_file).validate_twine_file
     end
   end
+
+  def test_reports_python_specific_placeholders
+    random_definition.translations["en"] = "%(python_only)s"
+
+    assert_raises Twine::Error do
+      Twine::Runner.new(@options, @twine_file).validate_twine_file
+    end
+  end
 end