multilist: ensure min <= max

Author: sveinn

lib/tty/prompt/multi_list.rb

@@ -23,6 +23,8 @@ def initialize(prompt, **options)
         @echo = options.fetch(:echo, true)
         @min  = options[:min]
         @max  = options[:max]
+        error = "min must not be greater than max"
+        raise ConfigurationError, error if @min && @max && @min > @max
       end
 
       # Set a minimum number of choices

spec/unit/multi_select_spec.rb

@@ -916,25 +916,40 @@ def exit_message(prompt, choices)
     let(:spacebar) { " " }
     let(:enter) { "\r" }
     before do
-      prompt.on(:keypress) { |e| prompt.trigger(:keydown) if e.value == keydown }
+      prompt.on(:keypress) do |e|
+        prompt.trigger(:keydown) if e.value == keydown
+      end
     end
-    it "requires a min number of choices" do
-      prompt.input << spacebar << enter << keydown << spacebar << enter
-      prompt.input.rewind
-
-      value = prompt.multi_select("What letter?", choices, min: 2, max: 2, per_page: choices.count)
-      expect(value).to eq(%w[A B])
-
-      expected_output =
-        output_helper("What letter?", choices, "A", [], init: true, min: 2, max: 2,
-          hint: "Press #{up_down} arrow to move, Space to select and Enter to finish") +
-        output_helper("What letter?", choices, "A", %w[A], min: 2, max: 2) +
-        output_helper("What letter?", choices, "A", %w[A], min: 2, max: 2) +
-        output_helper("What letter?", choices, "B", %w[A], min: 2, max: 2) +
-        output_helper("What letter?", choices, "B", %w[A B], min: 2, max: 2) +
-        exit_message("What letter?", %w[A B])
-
-      expect(prompt.output.string).to eq(expected_output)
+    context "with min <= max" do
+      let(:min) { 2 }
+      let(:max) { 2 }
+      it "requires a min number of choices" do
+        prompt.input << spacebar << enter << keydown << spacebar << enter
+        prompt.input.rewind
+
+        value = prompt.multi_select("What letter?", choices, min: min, max: max, per_page: choices.count)
+        expect(value).to eq(%w[A B])
+
+        expected_output =
+          output_helper("What letter?", choices, "A", [], init: true, min: min, max: max,
+            hint: "Press #{up_down} arrow to move, Space to select and Enter to finish") +
+          output_helper("What letter?", choices, "A", %w[A], min: min, max: max) +
+          output_helper("What letter?", choices, "A", %w[A], min: min, max: max) +
+          output_helper("What letter?", choices, "B", %w[A], min: min, max: max) +
+          output_helper("What letter?", choices, "B", %w[A B], min: min, max: max) +
+          exit_message("What letter?", %w[A B])
+
+        expect(prompt.output.string).to eq(expected_output)
+      end
+    end
+    context "with min > max" do
+      let(:min) { 3 }
+      let(:max) { 2 }
+      it "raises an error message" do
+        options = { min: min, max: max, per_page: choices.count }
+        error_msg = "min must not be greater than max"
+        expect { prompt.multi_select("What letter?", choices, options) }.to raise_error(TTY::Prompt::ConfigurationError, error_msg)
+      end
     end
   end
 end