1 files changed, 138 insertions, 0 deletions
diff --git a/spec/ruby/core/io/pread_spec.rb b/spec/ruby/core/io/pread_spec.rb
new file mode 100644
index 0000000000..cfb8dc4c68
--- /dev/null
+++ b/spec/ruby/core/io/pread_spec.rb
@@ -0,0 +1,138 @@
+# -*- encoding: utf-8 -*-
+require_relative '../../spec_helper'
+
+describe "IO#pread" do
+  before :each do
+    @fname = tmp("io_pread.txt")
+    @contents = "1234567890"
+    touch(@fname) { |f| f.write @contents }
+    @file = File.open(@fname, "r+")
+  end
+
+  after :each do
+    @file.close
+    rm_r @fname
+  end
+
+  it "accepts a length, and an offset" do
+    @file.pread(4, 0).should == "1234"
+    @file.pread(3, 4).should == "567"
+  end
+
+  it "accepts a length, an offset, and an output buffer" do
+    buffer = +"foo"
+    @file.pread(3, 4, buffer).should.equal?(buffer)
+    buffer.should == "567"
+  end
+
+  it "shrinks the buffer in case of less bytes read" do
+    buffer = +"foo"
+    @file.pread(1, 0, buffer)
+    buffer.should == "1"
+  end
+
+  it "grows the buffer in case of more bytes read" do
+    buffer = +"foo"
+    @file.pread(5, 0, buffer)
+    buffer.should == "12345"
+  end
+
+  it "preserves the encoding of the given buffer" do
+    buffer = ''.encode(Encoding::ISO_8859_1)
+    @file.pread(10, 0, buffer)
+
+    buffer.encoding.should == Encoding::ISO_8859_1
+  end
+
+  it "does not advance the file pointer" do
+    @file.pread(4, 0).should == "1234"
+    @file.read.should == "1234567890"
+  end
+
+  it "ignores the current offset" do
+    @file.pos = 3
+    @file.pread(4, 0).should == "1234"
+  end
+
+  it "returns an empty string for maxlen = 0" do
+    @file.pread(0, 4).should == ""
+  end
+
+  it "returns a buffer for maxlen = 0 when buffer specified" do
+    buffer = +"foo"
+    @file.pread(0, 4, buffer).should.equal?(buffer)
+    buffer.should == "foo"
+  end
+
+  it "ignores the offset for maxlen = 0, even if it is out of file bounds" do
+    @file.pread(0, 400).should == ""
+  end
+
+  it "does not reset the buffer when reading with maxlen = 0" do
+    buffer = +"foo"
+    @file.pread(0, 4, buffer)
+    buffer.should == "foo"
+
+    @file.pread(0, 400, buffer)
+    buffer.should == "foo"
+  end
+
+  it "converts maxlen to Integer using #to_int" do
+    maxlen = mock('maxlen')
+    maxlen.should_receive(:to_int).and_return(4)
+    @file.pread(maxlen, 0).should == "1234"
+  end
+
+  it "converts offset to Integer using #to_int" do
+    offset = mock('offset')
+    offset.should_receive(:to_int).and_return(0)
+    @file.pread(4, offset).should == "1234"
+  end
+
+  it "converts a buffer to String using to_str" do
+    buffer = mock('buffer')
+    buffer.should_receive(:to_str).at_least(1).and_return(+"foo")
+    @file.pread(4, 0, buffer)
+    buffer.should_not.is_a?(String)
+    buffer.to_str.should == "1234"
+  end
+
+  it "raises TypeError if maxlen is not an Integer and cannot be coerced into Integer" do
+    maxlen = Object.new
+    -> { @file.pread(maxlen, 0) }.should.raise(TypeError, 'no implicit conversion of Object into Integer')
+  end
+
+  it "raises TypeError if offset is not an Integer and cannot be coerced into Integer" do
+    offset = Object.new
+    -> { @file.pread(4, offset) }.should.raise(TypeError, 'no implicit conversion of Object into Integer')
+  end
+
+  it "raises ArgumentError for negative values of maxlen" do
+    -> { @file.pread(-4, 0) }.should.raise(ArgumentError, 'negative string size (or size too big)')
+  end
+
+  it "raised Errno::EINVAL for negative values of offset" do
+    -> { @file.pread(4, -1) }.should.raise(Errno::EINVAL, /Invalid argument/)
+  end
+
+  it "raises TypeError if the buffer is not a String and cannot be coerced into String" do
+    buffer = Object.new
+    -> { @file.pread(4, 0, buffer) }.should.raise(TypeError, 'no implicit conversion of Object into String')
+  end
+
+  it "raises EOFError if end-of-file is reached" do
+    -> { @file.pread(1, 10) }.should.raise(EOFError)
+  end
+
+  it "raises IOError when file is not open in read mode" do
+    File.open(@fname, "w") do |file|
+      -> { file.pread(1, 1) }.should.raise(IOError)
+    end
+  end
+
+  it "raises IOError when file is closed" do
+    file = File.open(@fname, "r+")
+    file.close
+    -> { file.pread(1, 1) }.should.raise(IOError)
+  end
+end