From 7671606ddcd0e16f1b31dd8e71635913771ed127 Mon Sep 17 00:00:00 2001
From: Markus Reiter <me@reitermark.us>
Date: Wed, 20 Jun 2018 20:32:28 +0200
Subject: [PATCH] Add `Formatter::enumeration`.

---
 Library/Homebrew/test/formatter_spec.rb | 18 ++++++++++++++++++
 Library/Homebrew/utils/formatter.rb     |  7 +++++++
 2 files changed, 25 insertions(+)

diff --git a/Library/Homebrew/test/formatter_spec.rb b/Library/Homebrew/test/formatter_spec.rb
index 14c63b8c3a..8d5ca8f41a 100644
--- a/Library/Homebrew/test/formatter_spec.rb
+++ b/Library/Homebrew/test/formatter_spec.rb
@@ -76,4 +76,22 @@ describe Formatter do
       expect(described_class.pluralize(2, "new formula")).to eq("2 new formulae")
     end
   end
+
+  describe "::enumeration" do
+    it "returns nil if given no arguments" do
+      expect(described_class.enumeration).to be nil
+    end
+
+    it "returns the input as string if there is only one argument" do
+      expect(described_class.enumeration(1)).to eq("1")
+    end
+
+    it "concatenates two items with “and”" do
+      expect(described_class.enumeration(1, 2)).to eq("1 and 2")
+    end
+
+    it "concatenates all items with a comma and appends the last with “and”" do
+      expect(described_class.enumeration(1, 2, 3)).to eq("1, 2 and 3")
+    end
+  end
 end
diff --git a/Library/Homebrew/utils/formatter.rb b/Library/Homebrew/utils/formatter.rb
index ec144bf2f8..e6bdf6f034 100644
--- a/Library/Homebrew/utils/formatter.rb
+++ b/Library/Homebrew/utils/formatter.rb
@@ -108,4 +108,11 @@ module Formatter
 
     show_count ? "#{count} #{words}" : words
   end
+
+  def enumeration(*items)
+    *items, last = items.map(&:to_s)
+    return last if items.empty?
+
+    "#{items.join(", ")} and #{last}"
+  end
 end