1 files changed, 52 insertions, 0 deletions
diff --git a/spec/ruby/command_line/dash_upper_u_spec.rb b/spec/ruby/command_line/dash_upper_u_spec.rb
new file mode 100644
index 0000000000..2c210eb603
--- /dev/null
+++ b/spec/ruby/command_line/dash_upper_u_spec.rb
@@ -0,0 +1,52 @@
+require_relative '../spec_helper'
+
+describe "ruby -U" do
+  it "sets Encoding.default_internal to UTF-8" do
+    ruby_exe('print Encoding.default_internal.name',
+             options: '-U').should == 'UTF-8'
+  end
+
+  it "sets Encoding.default_internal to UTF-8 when RUBYOPT is empty or only spaces" do
+    ruby_exe('p Encoding.default_internal',
+             options: '-U', env: { 'RUBYOPT' => '' }).should == "#<Encoding:UTF-8>\n"
+    ruby_exe('p Encoding.default_internal',
+             options: '-U', env: { 'RUBYOPT' => '  ' }).should == "#<Encoding:UTF-8>\n"
+  end
+
+  it "does nothing different if specified multiple times" do
+    ruby_exe('print Encoding.default_internal.name',
+             options: '-U -U').should == 'UTF-8'
+  end
+
+  it "is overruled by Encoding.default_internal=" do
+    ruby_exe('Encoding.default_internal="ascii"; print Encoding.default_internal.name',
+             options: '-U').should == 'US-ASCII'
+  end
+
+  it "does not affect the default external encoding" do
+    ruby_exe('Encoding.default_external="ascii"; print Encoding.default_external.name',
+             options: '-U').should == 'US-ASCII'
+  end
+
+  it "does not affect the source encoding" do
+    ruby_exe("print __ENCODING__.name",
+             options: '-U -KE').should == 'EUC-JP'
+    ruby_exe("print __ENCODING__.name",
+             options: '-KE -U').should == 'EUC-JP'
+  end
+
+  # I assume IO redirection will break on Windows...
+  it "raises a RuntimeError if used with -Eext:int" do
+    ruby_exe("p 1",
+             options: '-U -Eascii:ascii',
+             args: '2>&1',
+             exit_status: 1).should =~ /RuntimeError/
+  end
+
+  it "raises a RuntimeError if used with -E:int" do
+    ruby_exe("p 1",
+             options: '-U -E:ascii',
+             args: '2>&1',
+             exit_status: 1).should =~ /RuntimeError/
+  end
+end