1 files changed, 11 insertions, 12 deletions

diff --git a/spec/ruby/core/string/ascii_only_spec.rb b/spec/ruby/core/string/ascii_only_spec.rb
index c7e02fd874..88a0559cfd 100644
--- a/spec/ruby/core/string/ascii_only_spec.rb
+++ b/spec/ruby/core/string/ascii_only_spec.rb
@@ -7,12 +7,12 @@ describe "String#ascii_only?" do
     it "returns true if the encoding is UTF-8" do
       [ ["hello",                         true],
         ["hello".encode('UTF-8'),         true],
-        ["hello".force_encoding('UTF-8'), true],
+        ["hello".dup.force_encoding('UTF-8'), true],
       ].should be_computed_by(:ascii_only?)
     end
 
     it "returns true if the encoding is US-ASCII" do
-      "hello".force_encoding(Encoding::US_ASCII).ascii_only?.should be_true
+      "hello".dup.force_encoding(Encoding::US_ASCII).ascii_only?.should be_true
       "hello".encode(Encoding::US_ASCII).ascii_only?.should be_true
     end
 
@@ -34,13 +34,13 @@ describe "String#ascii_only?" do
       [ ["\u{6666}",                          false],
         ["hello, \u{6666}",                   false],
         ["\u{6666}".encode('UTF-8'),          false],
-        ["\u{6666}".force_encoding('UTF-8'),  false],
+        ["\u{6666}".dup.force_encoding('UTF-8'),  false],
       ].should be_computed_by(:ascii_only?)
     end
 
     it "returns false if the encoding is US-ASCII" do
-      [ ["\u{6666}".force_encoding(Encoding::US_ASCII),         false],
-        ["hello, \u{6666}".force_encoding(Encoding::US_ASCII),  false],
+      [ ["\u{6666}".dup.force_encoding(Encoding::US_ASCII),         false],
+        ["hello, \u{6666}".dup.force_encoding(Encoding::US_ASCII),  false],
       ].should be_computed_by(:ascii_only?)
     end
   end
@@ -51,17 +51,16 @@ describe "String#ascii_only?" do
   end
 
   it "returns false for the empty String with a non-ASCII-compatible encoding" do
-    "".force_encoding('UTF-16LE').ascii_only?.should be_false
+    "".dup.force_encoding('UTF-16LE').ascii_only?.should be_false
     "".encode('UTF-16BE').ascii_only?.should be_false
   end
 
   it "returns false for a non-empty String with non-ASCII-compatible encoding" do
-    "\x78\x00".force_encoding("UTF-16LE").ascii_only?.should be_false
+    "\x78\x00".dup.force_encoding("UTF-16LE").ascii_only?.should be_false
   end
 
   it "returns false when interpolating non ascii strings" do
-    base = "EU currency is"
-    base.force_encoding(Encoding::US_ASCII)
+    base = "EU currency is".dup.force_encoding(Encoding::US_ASCII)
     euro = "\u20AC"
     interp = "#{base} #{euro}"
     euro.ascii_only?.should be_false
@@ -70,14 +69,14 @@ describe "String#ascii_only?" do
   end
 
   it "returns false after appending non ASCII characters to an empty String" do
-    ("" << "λ").ascii_only?.should be_false
+    ("".dup << "λ").ascii_only?.should be_false
   end
 
   it "returns false when concatenating an ASCII and non-ASCII String" do
-    "".concat("λ").ascii_only?.should be_false
+    "".dup.concat("λ").ascii_only?.should be_false
   end
 
   it "returns false when replacing an ASCII String with a non-ASCII String" do
-    "".replace("λ").ascii_only?.should be_false
+    "".dup.replace("λ").ascii_only?.should be_false
   end
 end