Convert String test to spec.

Library/Homebrew/test/string_spec.rb

+require "extend/string"
+
+describe String do
+  describe "#undent" do
+    it "removes leading whitespace, taking the first line as reference" do
+      string = <<-EOS.undent
+        hi
+........my friend over
+          there
+      EOS
+
+      expect(string).to eq("hi\n........my friend over\n  there\n")
+    end
+
+    it "removes nothing if the text is not indented" do
+      string = <<-EOS.undent
+hi
+I'm not indented
+      EOS
+
+      expect(string).to eq("hi\nI'm not indented\n")
+    end
+
+    it "can be nested" do
+      nested_string = <<-EOS.undent
+        goodbye
+      EOS
+
+      string = <<-EOS.undent
+        hello
+        #{nested_string}
+      EOS
+
+      expect(string).to eq("hello\ngoodbye\n\n")
+    end
+  end
+end
+
+describe StringInreplaceExtension do
+  subject { string.extend(described_class) }
+  let(:string) { "foobar" }
+
+  describe "#sub!" do
+    it "adds an error to #errors when no replacement was made" do
+      subject.sub! "not here", "test"
+      expect(subject.errors).to eq(['expected replacement of "not here" with "test"'])
+    end
+  end
+end

Library/Homebrew/test/string_test.rb

-require "testing_env"
-require "extend/string"
-
-class StringTest < Homebrew::TestCase
-  def test_undent
-    undented = <<-EOS.undent
-    hi
-....my friend over
-    there
-    EOS
-    assert_equal "hi\n....my friend over\nthere\n", undented
-  end
-
-  def test_undent_not_indented
-    undented = <<-EOS.undent
-hi
-I'm not indented
-    EOS
-    assert_equal "hi\nI'm not indented\n", undented
-  end
-
-  def test_undent_nested
-    nest = <<-EOS.undent
-      goodbye
-    EOS
-
-    undented = <<-EOS.undent
-      hello
-      #{nest}
-    EOS
-
-    assert_equal "hello\ngoodbye\n\n", undented
-  end
-
-  def test_inreplace_sub_failure
-    s = "foobar".extend StringInreplaceExtension
-    s.sub! "not here", "test"
-    assert_equal ['expected replacement of "not here" with "test"'], s.errors
-  end
-end