1 files changed, 91 insertions, 0 deletions
diff --git a/spec/ruby/library/stringio/printf_spec.rb b/spec/ruby/library/stringio/printf_spec.rb
new file mode 100644
index 0000000000..ca82e84757
--- /dev/null
+++ b/spec/ruby/library/stringio/printf_spec.rb
@@ -0,0 +1,91 @@
+require_relative '../../spec_helper'
+require_relative 'fixtures/classes'
+require_relative '../../core/kernel/shared/sprintf'
+
+describe "StringIO#printf" do
+  before :each do
+    @io = StringIO.new()
+  end
+
+  it "returns nil" do
+    @io.printf("%d %04x", 123, 123).should be_nil
+  end
+
+  it "pads self with \\000 when the current position is after the end" do
+    @io.pos = 3
+    @io.printf("%d", 123)
+    @io.string.should == "\000\000\000123"
+  end
+
+  it "performs format conversion" do
+    @io.printf("%d %04x", 123, 123)
+    @io.string.should == "123 007b"
+  end
+
+  it "updates the current position" do
+    @io.printf("%d %04x", 123, 123)
+    @io.pos.should eql(8)
+
+    @io.printf("%d %04x", 123, 123)
+    @io.pos.should eql(16)
+  end
+
+  describe "formatting" do
+    it_behaves_like :kernel_sprintf, -> format, *args {
+      io = StringIO.new(+"")
+      io.printf(format, *args)
+      io.string
+    }
+  end
+end
+
+describe "StringIO#printf when in read-write mode" do
+  before :each do
+    @io = StringIO.new(+"example", "r+")
+  end
+
+  it "starts from the beginning" do
+    @io.printf("%s", "abcdefghijk")
+    @io.string.should == "abcdefghijk"
+  end
+
+  it "does not truncate existing string" do
+    @io.printf("%s", "abc")
+    @io.string.should == "abcmple"
+  end
+
+  it "correctly updates self's position" do
+    @io.printf("%s", "abc")
+    @io.pos.should eql(3)
+  end
+end
+
+describe "StringIO#printf when in append mode" do
+  before :each do
+    @io = StringIO.new(+"example", "a")
+  end
+
+  it "appends the passed argument to the end of self" do
+    @io.printf("%d %04x", 123, 123)
+    @io.string.should == "example123 007b"
+
+    @io.printf("%d %04x", 123, 123)
+    @io.string.should == "example123 007b123 007b"
+  end
+
+  it "correctly updates self's position" do
+    @io.printf("%d %04x", 123, 123)
+    @io.pos.should eql(15)
+  end
+end
+
+describe "StringIO#printf when self is not writable" do
+  it "raises an IOError" do
+    io = StringIO.new(+"test", "r")
+    -> { io.printf("test") }.should raise_error(IOError)
+
+    io = StringIO.new(+"test")
+    io.close_write
+    -> { io.printf("test") }.should raise_error(IOError)
+  end
+end