require 'test_helper'
require 'rantly/shrinks'
require 'rantly/minitest_extensions'

module RantlyTest
end

module RantlyTest::Shrinkers
end

describe Integer do

  it "not be able to shrink 0 integer" do
    assert !0.shrinkable?
  end

  it "shrink positive integers to something less than itself" do
    assert(3.shrink < 3)
    assert(2.shrink < 2)
    assert_equal(0,1.shrink)
  end

  it "shrink negative integers to something larger than itself" do
    assert(-3.shrink > -3)
    assert(-2.shrink > -2)
    assert_equal(0,-1.shrink)
  end

  it "shrink 0 to itself" do
    # hmm. should this be undefined?
    assert_equal 0.shrink, 0
  end
end

describe String do

  it "not be able to shrink empty string" do
    assert !"".shrinkable?
  end

  it "shrink a string one char shorter" do
    property_of {
      sized(10) { string }
    }.check { |str|
      assert_equal 9, str.shrink.length
    }
  end
end

describe Array do

  it "not be able to shrink empty array" do
    assert ![].shrinkable?
  end

  it "shrink array by trying to shrink the first shrinkable element available" do
    assert_equal [0,1], [1,1].shrink
    assert_equal [0,0,1], [0,1,1].shrink
  end

  it "shrink array by 1 if none of the element in it is shrinkable" do
    property_of {
      n = integer(1..10)
      a = Array.new(n,0)
      [n,a]
    }.check { |n,a|
      assert_equal n-1, a.shrink.length
    }
  end
end

describe Hash do

  it "not be able to shrink empty hash" do
    assert !{}.shrinkable?
  end

  it "shrink a value if one of the values is shrinkable" do
    assert_equal({foo: 0, bar: 0}, {foo: 1, bar: 0}.shrink)
    assert_equal({foo: 0, bar: 0}, {foo: 0, bar: 1}.shrink)
  end

  it "shrink by deleting an element in it if none of the values is shrinkable" do
    assert_equal({},{foo: 0}.shrink)
  end
end

describe "Shrinker Test" do

  it "shrink data to smallest value that fails assertion" do
    # We try to generate an array of 10 elements, filled with ones.
    # The property we try to test is that non of the element is
    # larger than 1, and the array's length is less than 4.
    test = property_of {
      a = Array.new(10,1)
      i = Random::rand(a.length)
      a[i] = 1
      a
    }
    assert_raises MiniTest::Assertion do
      test.check { |a|
        assert(!a.any? { |e| e > 0 } && a.length < 4,"contains 1")
      }
    end

    assert_equal [0,0,0,0], test.shrunk_failed_data
  end
end