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require_relative '../../spec_helper'
require_relative 'fixtures/classes'
describe "BasicObject#instance_eval" do
before :each do
ScratchPad.clear
end
it "is a public instance method" do
BasicObject.should have_public_instance_method(:instance_eval)
end
it "sets self to the receiver in the context of the passed block" do
a = BasicObject.new
a.instance_eval { self }.equal?(a).should be_true
end
it "evaluates strings" do
a = BasicObject.new
a.instance_eval('self').equal?(a).should be_true
end
it "expects a block with no arguments" do
-> { "hola".instance_eval }.should raise_error(ArgumentError)
end
it "takes no arguments with a block" do
-> { "hola".instance_eval(4, 5) {|a,b| a + b } }.should raise_error(ArgumentError)
end
it "yields the object to the block" do
"hola".instance_eval {|o| ScratchPad.record o }
ScratchPad.recorded.should == "hola"
end
it "returns the result of the block" do
"hola".instance_eval { :result }.should == :result
end
it "only binds the eval to the receiver" do
f = Object.new
f.instance_eval do
def foo
1
end
end
f.foo.should == 1
-> { Object.new.foo }.should raise_error(NoMethodError)
end
it "preserves self in the original block when passed a block argument" do
prc = proc { self }
old_self = prc.call
new_self = Object.new
new_self.instance_eval(&prc).should == new_self
prc.call.should == old_self
end
# TODO: This should probably be replaced with a "should behave like" that uses
# the many scoping/binding specs from kernel/eval_spec, since most of those
# behaviors are the same for instance_eval. See also module_eval/class_eval.
it "binds self to the receiver" do
s = "hola"
(s == s.instance_eval { self }).should be_true
o = mock('o')
(o == o.instance_eval("self")).should be_true
end
it "executes in the context of the receiver" do
"Ruby-fu".instance_eval { size }.should == 7
"hola".instance_eval("size").should == 4
Object.class_eval { "hola".instance_eval("to_s") }.should == "hola"
Object.class_eval { "Ruby-fu".instance_eval{ to_s } }.should == "Ruby-fu"
end
it "has access to receiver's instance variables" do
BasicObjectSpecs::IVars.new.instance_eval { @secret }.should == 99
BasicObjectSpecs::IVars.new.instance_eval("@secret").should == 99
end
it "treats block-local variables as local to the block" do
prc = instance_eval <<-CODE
proc do |x, prc|
if x
n = 2
else
n = 1
prc.call(true, prc)
n
end
end
CODE
prc.call(false, prc).should == 1
end
it "sets class variables in the receiver" do
BasicObjectSpecs::InstEvalCVar.class_variables.should include(:@@count)
BasicObjectSpecs::InstEvalCVar.send(:class_variable_get, :@@count).should == 2
end
it "makes the receiver metaclass the scoped class when used with a string" do
obj = Object.new
obj.instance_eval %{
class B; end
B
}
obj.singleton_class.const_get(:B).should be_an_instance_of(Class)
end
it "gets constants in the receiver if a string given" do
BasicObjectSpecs::InstEvalOuter::Inner::X_BY_STR.should == 2
end
it "doesn't get constants in the receiver if a block given" do
BasicObjectSpecs::InstEvalOuter::Inner::X_BY_BLOCK.should be_nil
end
it "raises a TypeError when defining methods on an immediate" do
-> do
1.instance_eval { def foo; end }
end.should raise_error(TypeError)
-> do
:foo.instance_eval { def foo; end }
end.should raise_error(TypeError)
end
quarantine! do # Not clean, leaves cvars lying around to break other specs
it "scopes class var accesses in the caller when called on a Fixnum" do
# Fixnum can take instance vars
Fixnum.class_eval "@@__tmp_instance_eval_spec = 1"
(defined? @@__tmp_instance_eval_spec).should be_nil
@@__tmp_instance_eval_spec = 2
1.instance_eval { @@__tmp_instance_eval_spec }.should == 2
Fixnum.__send__(:remove_class_variable, :@@__tmp_instance_eval_spec)
end
end
it "raises a TypeError when defining methods on numerics" do
-> do
(1.0).instance_eval { def foo; end }
end.should raise_error(TypeError)
-> do
(1 << 64).instance_eval { def foo; end }
end.should raise_error(TypeError)
end
it "evaluates procs originating from methods" do
def meth(arg); arg; end
m = method(:meth)
obj = Object.new
obj.instance_eval(&m).should == obj
end
it "evaluates string with given filename and linenumber" do
err = begin
Object.new.instance_eval("raise", "a_file", 10)
rescue => e
e
end
err.backtrace.first.split(":")[0..1].should == ["a_file", "10"]
end
it "evaluates string with given filename and negative linenumber" do
err = begin
Object.new.instance_eval("\n\nraise\n", "b_file", -100)
rescue => e
e
end
err.backtrace.first.split(":")[0..1].should == ["b_file", "-98"]
end
it "has access to the caller's local variables" do
x = nil
instance_eval "x = :value"
x.should == :value
end
end
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