Add tests

Library/Homebrew/test/extend/blank_spec.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require "extend/blank"
+
+describe Object do
+  let(:empty_true) do
+    Class.new(described_class) do
+      def empty?
+        0
+      end
+    end
+  end
+  let(:empty_false) do
+    Class.new(described_class) do
+      def empty?
+        nil
+      end
+    end
+  end
+  let(:blank) { [empty_true.new, nil, false, "", "   ", "  \n\t  \r ", "　", "\u00a0", [], {}] }
+  let(:present) { [empty_false.new, described_class.new, true, 0, 1, "a", [nil], { nil => 0 }, Time.now] }
+
+  describe ".blank?" do
+    it "checks if an object is blank" do
+      blank.each { |v| expect(v.blank?).to be true }
+      present.each { |v| expect(v.blank?).to be false }
+    end
+
+    it "checks if an object is blank with bundled string encodings" do
+      Encoding.list.reject(&:dummy?).each do |encoding|
+        expect(" ".encode(encoding).blank?).to be true
+        expect("a".encode(encoding).blank?).to be false
+      end
+    end
+  end
+
+  describe ".present?" do
+    it "checks if an object is present" do
+      blank.each { |v| expect(v.present?).to be false }
+      present.each { |v| expect(v.present?).to be true }
+    end
+  end
+
+  describe ".presence" do
+    it "returns the object if present, or nil" do
+      blank.each { |v| expect(v.presence).to be_nil }
+      present.each { |v| expect(v.presence).to be v }
+    end
+  end
+end