1 files changed, 41 insertions, 0 deletions
diff --git a/spec/rubyspec/library/stringscanner/pre_match_spec.rb b/spec/rubyspec/library/stringscanner/pre_match_spec.rb
new file mode 100644
index 0000000000..0d4759dc5c
--- /dev/null
+++ b/spec/rubyspec/library/stringscanner/pre_match_spec.rb
@@ -0,0 +1,41 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../shared/extract_range_matched', __FILE__)
+require 'strscan'
+
+describe "StringScanner#pre_match" do
+  before :each do
+    @s = StringScanner.new("This is a test")
+  end
+
+  it "returns the pre-match (in the regular expression sense) of the last scan" do
+    @s.pre_match.should == nil
+    @s.scan(/\w+\s/)
+    @s.pre_match.should == ""
+    @s.getch
+    @s.pre_match.should == "This "
+    @s.get_byte
+    @s.pre_match.should == "This i"
+    @s.get_byte
+    @s.pre_match.should == "This is"
+  end
+
+  it "returns nil if there's no match" do
+    @s.scan(/\s+/)
+    @s.pre_match.should == nil
+  end
+
+  it "is more than just the data from the last match" do
+    @s.scan(/\w+/)
+    @s.scan_until(/a te/)
+    @s.pre_match.should == "This is "
+  end
+
+  it "is not changed when the scanner's position changes" do
+    @s.scan_until(/\s+/)
+    @s.pre_match.should == "This"
+    @s.pos -= 1
+    @s.pre_match.should == "This"
+  end
+
+  it_behaves_like :extract_range_matched, :pre_match
+end