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Forked from r00k/inject_spec.rb
Last active Aug 29, 2015
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require 'rspec'
def sum(numbers)
numbers.inject(0) { |sum, number| sum + number }
end
def product(numbers)
numbers.inject(1) { |sum, number| sum * number }
end
# EASIER: Write product, a method that accepts an
# array of numbers, and multiplies them all together.
# HARDER: Write a method that accepts an array
# of strings.
# Return a hash where the keys are the strings
# and the values are the length of each string.
#
# hash_of_lengths(["foo", "ab"]) =>
# { "foo" => 3, "ab" => 2 }
describe "#sum" do
it "returns the sum of an array of numbers" do
numbers = [1, 2, 3, 4]
result = sum(numbers)
expect(result).to eq 10
end
end
def hash_of_lengths(strings)
strings.inject({}) { |hsh, string| hsh[string] = string.length ; hsh }
end
describe "#hash_of_lengths" do
it "returns a hash where keys are strings and values are their lengths" do
strings = ["a", "bb", "ccc"]
result = hash_of_lengths(strings)
expect(result).to eq({ "a" => 1, "bb" => 2, "ccc" => 3 })
end
end
# Harder: Write a method that takes an element and a collection
# and returns true if the collection contains only things
# that are == to that element.
# Easier: do hash_of_lengths
#
describe "#all_equal" do
context "when all elements in collection == argument" do
it "returns true" do
result = all_equal("foo", ["foo", "foo"])
expect(result).to be_truthy
end
end
context "when all elements are not == to argument" do
it "returns false" do
result = all_equal("foo", ["foo", "bar"])
expect(result).to be_falsey
end
end
end
def all_equal(argument, collection)
collection.inject(true) { |result, element| result && element == argument }
end
count = 0
foos.each do |foo|
count += 1 if foo.valid?
end
count
foos.inject(0) { |result, foo| result + 1 if foo.valid? ; result }
foos.count { |foo| foo.valid? }
results = []
foos.each do |foo|
if whatever
results << foo
end
end
results
foos.inject([]) { |acc, element| acc << element if whatever ; acc }
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