1 files changed, 93 insertions, 0 deletions
diff --git a/spec/rubyspec/core/kernel/instance_variable_set_spec.rb b/spec/rubyspec/core/kernel/instance_variable_set_spec.rb
new file mode 100644
index 0000000000..bac1bb5f99
--- /dev/null
+++ b/spec/rubyspec/core/kernel/instance_variable_set_spec.rb
@@ -0,0 +1,93 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../fixtures/classes', __FILE__)
+
+describe "Kernel#instance_variable_set" do
+  it "sets the value of the specified instance variable" do
+    class Dog
+      def initialize(p1, p2)
+        @a, @b = p1, p2
+      end
+    end
+    Dog.new('cat', 99).instance_variable_set(:@a, 'dog').should == "dog"
+  end
+
+  it "sets the value of the instance variable when no instance variables exist yet" do
+    class NoVariables; end
+    NoVariables.new.instance_variable_set(:@a, "new").should == "new"
+  end
+
+  it "raises a NameError exception if the argument is not of form '@x'" do
+    class NoDog; end
+    lambda { NoDog.new.instance_variable_set(:c, "cat") }.should raise_error(NameError)
+  end
+
+  it "raises a NameError exception if the argument is an invalid instance variable name" do
+    class DigitDog; end
+    lambda { DigitDog.new.instance_variable_set(:"@0", "cat") }.should raise_error(NameError)
+  end
+
+  it "raises a NameError when the argument is '@'" do
+    class DogAt; end
+    lambda { DogAt.new.instance_variable_set(:"@", "cat") }.should raise_error(NameError)
+  end
+
+  it "raises a TypeError if the instance variable name is a Fixnum" do
+    lambda { "".instance_variable_set(1, 2) }.should raise_error(TypeError)
+  end
+
+  it "raises a TypeError if the instance variable name is an object that does not respond to to_str" do
+    class KernelSpecs::A; end
+    lambda { "".instance_variable_set(KernelSpecs::A.new, 3) }.should raise_error(TypeError)
+  end
+
+  it "raises a NameError if the passed object, when coerced with to_str, does not start with @" do
+    class KernelSpecs::B
+      def to_str
+        ":c"
+      end
+    end
+    lambda { "".instance_variable_set(KernelSpecs::B.new, 4) }.should raise_error(NameError)
+  end
+
+  it "raises a NameError if pass an object that cannot be a symbol" do
+    lambda { "".instance_variable_set(:c, 1) }.should raise_error(NameError)
+  end
+
+  it "accepts as instance variable name any instance of a class that responds to to_str" do
+    class KernelSpecs::C
+      def initialize
+        @a = 1
+      end
+      def to_str
+        "@a"
+      end
+    end
+    KernelSpecs::C.new.instance_variable_set(KernelSpecs::C.new, 2).should == 2
+  end
+
+  describe "on frozen objects" do
+    before :each do
+      klass = Class.new do
+        attr_reader :ivar
+        def initialize
+          @ivar = :origin
+        end
+      end
+
+      @frozen = klass.new.freeze
+    end
+
+    it "keeps stored object after any exceptions" do
+      lambda { @frozen.instance_variable_set(:@ivar, :replacement) }.should raise_error(Exception)
+      @frozen.ivar.should equal(:origin)
+    end
+
+    it "raises a RuntimeError when passed replacement is identical to stored object" do
+      lambda { @frozen.instance_variable_set(:@ivar, :origin) }.should raise_error(RuntimeError)
+    end
+
+    it "raises a RuntimeError when passed replacement is different from stored object" do
+      lambda { @frozen.instance_variable_set(:@ivar, :replacement) }.should raise_error(RuntimeError)
+    end
+  end
+end