Fix invalid "hint" attribute in forms

Using `hint: false` was generating an input with `hint="false"` instead
of generating no hint at all.

spec/lib/consul_form_builder_spec.rb

@@ -0,0 +1,42 @@
+require "rails_helper"
+
+describe ConsulFormBuilder do
+  class DummyModel
+    include ActiveModel::Model
+    attr_accessor :title
+  end
+
+  let(:builder) { ConsulFormBuilder.new(:dummy, DummyModel.new, ActionView::Base.new, {}) }
+
+  describe "hints" do
+    it "does not generate hints by default" do
+      render builder.text_field(:title)
+
+      expect(page).not_to have_css ".help-text"
+      expect(page).not_to have_css "input[aria-describedby]"
+    end
+
+    it "generates text with a hint if provided" do
+      render builder.text_field(:title, hint: "Make it quick")
+
+      expect(page).to have_css ".help-text", text: "Make it quick"
+      expect(page).to have_css "input[aria-describedby='dummy_title-help-text']"
+    end
+
+    it "does not generate a hint attribute" do
+      render builder.text_field(:title)
+
+      expect(page).not_to have_css "input[hint]"
+    end
+  end
+
+  attr_reader :content
+
+  def render(content)
+    @content = content
+  end
+
+  def page
+    Capybara::Node::Simple.new(content)
+  end
+end