81 lines
1.9 KiB
Ruby
81 lines
1.9 KiB
Ruby
require_relative '../spec_helper'
|
|
|
|
describe "The '&&' statement" do
|
|
|
|
it "short-circuits evaluation at the first condition to be false" do
|
|
x = nil
|
|
true && false && x = 1
|
|
x.should be_nil
|
|
end
|
|
|
|
it "evaluates to the first condition not to be true" do
|
|
value = nil
|
|
(value && nil).should == nil
|
|
(value && false).should == nil
|
|
value = false
|
|
(value && nil).should == false
|
|
(value && false).should == false
|
|
|
|
("yes" && 1 && nil && true).should == nil
|
|
("yes" && 1 && false && true).should == false
|
|
end
|
|
|
|
it "evaluates to the last condition if all are true" do
|
|
("yes" && 1).should == 1
|
|
(1 && "yes").should == "yes"
|
|
end
|
|
|
|
it "evaluates the full set of chained conditions during assignment" do
|
|
x, y = nil
|
|
x = 1 && y = 2
|
|
# "1 && y = 2" is evaluated and then assigned to x
|
|
x.should == 2
|
|
end
|
|
|
|
it "treats empty expressions as nil" do
|
|
(() && true).should be_nil
|
|
(true && ()).should be_nil
|
|
(() && ()).should be_nil
|
|
end
|
|
|
|
end
|
|
|
|
describe "The 'and' statement" do
|
|
it "short-circuits evaluation at the first condition to be false" do
|
|
x = nil
|
|
true and false and x = 1
|
|
x.should be_nil
|
|
end
|
|
|
|
it "evaluates to the first condition not to be true" do
|
|
value = nil
|
|
(value and nil).should == nil
|
|
(value and false).should == nil
|
|
value = false
|
|
(value and nil).should == false
|
|
(value and false).should == false
|
|
|
|
("yes" and 1 and nil and true).should == nil
|
|
("yes" and 1 and false and true).should == false
|
|
end
|
|
|
|
it "evaluates to the last condition if all are true" do
|
|
("yes" and 1).should == 1
|
|
(1 and "yes").should == "yes"
|
|
end
|
|
|
|
it "when used in assignment, evaluates and assigns expressions individually" do
|
|
x, y = nil
|
|
x = 1 and y = 2
|
|
# evaluates (x=1) and (y=2)
|
|
x.should == 1
|
|
end
|
|
|
|
it "treats empty expressions as nil" do
|
|
(() and true).should be_nil
|
|
(true and ()).should be_nil
|
|
(() and ()).should be_nil
|
|
end
|
|
|
|
end
|