1 files changed, 42 insertions, 0 deletions
diff --git a/spec/ruby/library/stringscanner/peek_spec.rb b/spec/ruby/library/stringscanner/peek_spec.rb
new file mode 100644
index 0000000000..5b54c6be0b
--- /dev/null
+++ b/spec/ruby/library/stringscanner/peek_spec.rb
@@ -0,0 +1,42 @@
+require_relative '../../spec_helper'
+require 'strscan'
+
+describe "StringScanner#peek" do
+  before :each do
+    @s = StringScanner.new('This is a test')
+  end
+
+  it "returns at most the specified number of bytes from the current position" do
+    @s.peek(4).should == "This"
+    @s.pos.should == 0
+    @s.pos = 5
+    @s.peek(2).should == "is"
+    @s.peek(1000).should == "is a test"
+
+    s = StringScanner.new("été")
+    s.peek(2).should == "é"
+  end
+
+  it "returns an empty string when the passed argument is zero" do
+    @s.peek(0).should == ""
+  end
+
+  it "raises a ArgumentError when the passed argument is negative" do
+    -> { @s.peek(-2) }.should.raise(ArgumentError)
+  end
+
+  it "raises a RangeError when the passed argument is a Bignum" do
+    -> { @s.peek(bignum_value) }.should.raise(RangeError)
+  end
+
+  it "returns an instance of String when passed a String subclass" do
+    cls = Class.new(String)
+    sub = cls.new("abc")
+
+    s = StringScanner.new(sub)
+
+    ch = s.peek(1)
+    ch.should_not.is_a?(cls)
+    ch.should.instance_of?(String)
+  end
+end