1 files changed, 76 insertions, 0 deletions
diff --git a/spec/ruby/core/file/extname_spec.rb b/spec/ruby/core/file/extname_spec.rb
new file mode 100644
index 0000000000..995d0ea31a
--- /dev/null
+++ b/spec/ruby/core/file/extname_spec.rb
@@ -0,0 +1,76 @@
+# -*- encoding: utf-8 -*-
+require_relative '../../spec_helper'
+
+describe "File.extname" do
+  it "returns the extension (the portion of file name in path after the period)" do
+    File.extname("foo.rb").should == ".rb"
+    File.extname("/foo/bar.rb").should == ".rb"
+    File.extname("/foo.rb/bar.c").should == ".c"
+    File.extname("bar").should == ""
+    File.extname(".bashrc").should == ""
+    File.extname("/foo.bar/baz").should == ""
+    File.extname(".app.conf").should == ".conf"
+  end
+
+  it "returns unfrozen strings" do
+    File.extname("foo.rb").frozen?.should == false
+    File.extname("/foo/bar.rb").frozen?.should == false
+    File.extname("/foo.rb/bar.c").frozen?.should == false
+    File.extname("bar").frozen?.should == false
+    File.extname(".bashrc").frozen?.should == false
+    File.extname("/foo.bar/baz").frozen?.should == false
+    File.extname(".app.conf").frozen?.should == false
+  end
+
+  it "returns the extension for edge cases" do
+    File.extname("").should ==  ""
+    File.extname(".").should ==  ""
+    File.extname("/").should ==  ""
+    File.extname("/.").should ==  ""
+    File.extname("..").should ==  ""
+    File.extname("...").should ==  ""
+    File.extname("....").should ==  ""
+  end
+
+  describe "for a filename ending with a dot" do
+    platform_is :windows do
+      it "returns ''" do
+        File.extname(".foo.").should == ""
+        File.extname("foo.").should == ""
+      end
+    end
+
+    platform_is_not :windows do
+      it "returns '.'" do
+        File.extname(".foo.").should == "."
+        File.extname("foo.").should == "."
+      end
+    end
+  end
+
+  it "returns only the last extension of a file with several dots" do
+    File.extname("a.b.c.d.e").should == ".e"
+  end
+
+  it "accepts an object that has a #to_path method" do
+    File.extname(mock_to_path("a.b.c.d.e")).should == ".e"
+  end
+
+  it "raises a TypeError if not passed a String type" do
+    -> { File.extname(nil)   }.should.raise(TypeError)
+    -> { File.extname(0)     }.should.raise(TypeError)
+    -> { File.extname(true)  }.should.raise(TypeError)
+    -> { File.extname(false) }.should.raise(TypeError)
+  end
+
+  it "raises an ArgumentError if not passed one argument" do
+    -> { File.extname }.should.raise(ArgumentError)
+    -> { File.extname("foo.bar", "foo.baz") }.should.raise(ArgumentError)
+  end
+
+
+  it "returns the extension for a multibyte filename" do
+    File.extname('Имя.m4a').should == ".m4a"
+  end
+
+end