Change to validate arity when parsing keywords

lib/tty/option/parser/keywords.rb

@@ -22,9 +22,12 @@ def initialize(keywords, **config)
           @remaining = []
           @names = {}
           @required = []
+          @arities = Hash.new(0)
+          @multiplies = {}
 
           @keywords.each do |kwarg|
             @names[kwarg.name.to_s] = kwarg
+            @multiplies[kwarg.name] = kwarg if kwarg.multiple?
 
             if kwarg.default?
               case kwarg.default
@@ -49,13 +52,15 @@ def parse(argv)
             kwarg, value = next_keyword
             break if kwarg.nil?
             @required.delete(kwarg)
+            @arities[kwarg.name] += 1
 
             if block_given?
               yield(kwarg, value)
             end
             assign_keyword(kwarg, value)
           end
 
+          check_arity
           check_required
 
           [@parsed, @remaining, @errors]
@@ -133,6 +138,36 @@ def record_error(type, message, arg = nil)
           end
         end
 
+        # Check if parameter matches arity
+        #
+        # @raise [InvalidArity]
+        #
+        # @api private
+        def check_arity
+          @multiplies.each do |name, kwarg|
+            arity = @arities[name]
+
+            if 0 < kwarg.arity.abs && arity < kwarg.arity.abs
+              prefix = kwarg.arity < 0 ? "at least " : ""
+              expected_arity = kwarg.arity < 0 ? kwarg.arity.abs - 1 : kwarg.arity
+
+              record_error(InvalidArity, format(
+                "expected keyword %s to appear %s but appeared %s",
+                name.inspect,
+                prefix + pluralize("time", expected_arity),
+                pluralize("time", arity)
+              ))
+            end
+          end
+        end
+
+        # Pluralize a noun
+        #
+        # @api private
+        def pluralize(noun, count = 1)
+          "#{count} #{noun}#{'s' unless count == 1}"
+        end
+
         # Check if required parameters are provided
         #
         # @raise [MissingParameter]

spec/unit/parser/keywords_spec.rb

@@ -75,6 +75,28 @@ def parse(argv, kwargs, **config)
       expect(rest).to eq(["foo=3"])
     end
 
+    it "doesn't find enough keywords to match specific arity" do
+      expect {
+        parse(%w[foo=1], keyword(:foo, arity: 2))
+      }.to raise_error(TTY::Option::InvalidArity,
+                      "expected keyword :foo to appear 2 times but " \
+                      "appeared 1 time")
+    end
+
+    it "parses minimum number of keywords to satisfy at least arity" do
+      params, = parse(%w[foo=1 foo=2 foo=3], keyword(:foo, arity: -3))
+
+      expect(params[:foo]).to eq(%w[1 2 3])
+    end
+
+    it "doesn't find enough keywords to match at least arity" do
+      expect {
+        parse(%w[foo=1], keyword(:foo, arity: -3))
+      }.to raise_error(TTY::Option::InvalidArity,
+                      "expected keyword :foo to appear at least 2 times but " \
+                      "appeared 1 time")
+    end
+
     it "parses multiple keywords" do
       params, rest = parse(%w[foo=1 foo=2 foo=3], keyword(:foo, arity: :any))