diff --git a/Library/Homebrew/test/sandbox_spec.rb b/Library/Homebrew/test/sandbox_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..98634bf3cf2405a13bbe42d88d4dea98f1a468a3
--- /dev/null
+++ b/Library/Homebrew/test/sandbox_spec.rb
@@ -0,0 +1,78 @@
+require "sandbox"
+
+RSpec::Matchers.define_negated_matcher :not_matching, :matching
+
+describe Sandbox do
+  let(:dir) { @dir = Pathname.new(Dir.mktmpdir) }
+  let(:file) { dir/"foo" }
+
+  before(:each) do
+    skip "Sandbox not implemented." unless described_class.available?
+  end
+
+  after(:each) do
+    dir.rmtree unless @dir.nil?
+  end
+
+  specify "#formula?" do
+    f = formula { url "foo-1.0" }
+    f2 = formula { url "bar-1.0" }
+    allow(f2).to receive(:tap).and_return(Tap.fetch("test/tap"))
+
+    ENV["HOMEBREW_SANDBOX"] = "1"
+    expect(described_class).to be_formula(f), "Formulae should be sandboxed if --sandbox was passed."
+
+    ENV.delete("HOMEBREW_SANDBOX")
+    expect(described_class).to be_formula(f), "Formulae should be sandboxed if in a sandboxed tap."
+    expect(described_class).not_to be_formula(f2), "Formulae should not be sandboxed if not in a sandboxed tap."
+  end
+
+  specify "#test?" do
+    ENV.delete("HOMEBREW_NO_SANDBOX")
+    expect(described_class).to be_test, "Tests should be sandboxed unless --no-sandbox was passed."
+  end
+
+  specify "#allow_write" do
+    subject.allow_write file
+    subject.exec "touch", file
+
+    expect(file).to exist
+  end
+
+  describe "#exec" do
+    it "fails when writing to file not specified with ##allow_write" do
+      shutup do
+        expect {
+          subject.exec "touch", file
+        }.to raise_error(ErrorDuringExecution)
+      end
+
+      expect(file).not_to exist
+    end
+
+    it "complains on failure" do
+      ENV["HOMEBREW_VERBOSE"] = "1"
+
+      expect(Utils).to receive(:popen_read).and_return("foo")
+
+      expect { subject.exec "false" }
+        .to raise_error(ErrorDuringExecution)
+        .and output(/foo/).to_stdout
+    end
+
+    it "ignores bogus Python error" do
+      ENV["HOMEBREW_VERBOSE"] = "1"
+
+      with_bogus_error = <<-EOS.undent
+        foo
+        Mar 17 02:55:06 sandboxd[342]: Python(49765) deny file-write-unlink /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/errors.pyc
+        bar
+      EOS
+      expect(Utils).to receive(:popen_read).and_return(with_bogus_error)
+
+      expect { subject.exec "false" }
+        .to raise_error(ErrorDuringExecution)
+        .and output(a_string_matching(/foo/).and(matching(/bar/).and(not_matching(/Python/)))).to_stdout
+    end
+  end
+end
diff --git a/Library/Homebrew/test/sandbox_test.rb b/Library/Homebrew/test/sandbox_test.rb
deleted file mode 100644
index a633defce2d3ba12ea63436480ecb579b16d4069..0000000000000000000000000000000000000000
--- a/Library/Homebrew/test/sandbox_test.rb
+++ /dev/null
@@ -1,73 +0,0 @@
-require "testing_env"
-require "sandbox"
-
-class SandboxTest < Homebrew::TestCase
-  def setup
-    super
-    skip "sandbox not implemented" unless Sandbox.available?
-    @sandbox = Sandbox.new
-    @dir = Pathname.new(mktmpdir)
-    @file = @dir/"foo"
-  end
-
-  def test_formula?
-    f = formula { url "foo-1.0" }
-    f2 = formula { url "bar-1.0" }
-    f2.stubs(:tap).returns(Tap.fetch("test/tap"))
-
-    ENV["HOMEBREW_SANDBOX"] = "1"
-    assert Sandbox.formula?(f),
-      "Formulae should be sandboxed if --sandbox was passed."
-
-    ENV.delete("HOMEBREW_SANDBOX")
-    assert Sandbox.formula?(f),
-      "Formulae should be sandboxed if in a sandboxed tap."
-    refute Sandbox.formula?(f2),
-        "Formulae should not be sandboxed if not in a sandboxed tap."
-  end
-
-  def test_test?
-    ENV.delete("HOMEBREW_NO_SANDBOX")
-    assert Sandbox.test?,
-      "Tests should be sandboxed unless --no-sandbox was passed."
-  end
-
-  def test_allow_write
-    @sandbox.allow_write @file
-    @sandbox.exec "touch", @file
-    assert_predicate @file, :exist?
-  end
-
-  def test_deny_write
-    shutup do
-      assert_raises(ErrorDuringExecution) { @sandbox.exec "touch", @file }
-    end
-    refute_predicate @file, :exist?
-  end
-
-  def test_complains_on_failure
-    Utils.expects(popen_read: "foo")
-    ENV["HOMEBREW_VERBOSE"] = "1"
-    out, _err = capture_io do
-      assert_raises(ErrorDuringExecution) { @sandbox.exec "false" }
-    end
-    assert_match "foo", out
-  end
-
-  def test_ignores_bogus_python_error
-    with_bogus_error = <<-EOS.undent
-      foo
-      Mar 17 02:55:06 sandboxd[342]: Python(49765) deny file-write-unlink /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/errors.pyc
-      bar
-    EOS
-    Utils.expects(popen_read: with_bogus_error)
-    ENV["HOMEBREW_VERBOSE"] = "1"
-    out, _err = capture_io do
-      assert_raises(ErrorDuringExecution) { @sandbox.exec "false" }
-    end
-    refute_predicate out, :empty?
-    assert_match "foo", out
-    assert_match "bar", out
-    refute_match "Python", out
-  end
-end