observation_test.rb

describe Scientist::Observation do

  before do
    @experiment = Scientist::Experiment.new "test"
  end

  it "observes and records the execution of a block" do
    ob = Scientist::Observation.new("test", @experiment) do
      start_time = Time.now
      while Time.now - start_time < 0.1
        # Perform some CPU-intensive work
        (1..1000).each { |i| i * i }
      end
      "ret"
    end

    assert_equal "ret", ob.value
    refute ob.raised?
    assert_in_delta 0.1, ob.duration, 0.01
    assert_in_delta 0.1, ob.cpu_time, 0.01
  end

  it "stashes exceptions" do
    ob = Scientist::Observation.new("test", @experiment) do
      raise "exception"
    end

    assert ob.raised?
    assert_equal "exception", ob.exception.message
    assert_nil ob.value
  end

  describe "::RESCUES" do
    before do
      @original = Scientist::Observation::RESCUES.dup
    end

    after do
      Scientist::Observation::RESCUES.replace(@original)
    end

    it "includes all exception types by default" do
      ob = Scientist::Observation.new("test", @experiment) do
        raise Exception.new("not a StandardError")
      end

      assert ob.raised?
      assert_instance_of Exception, ob.exception
    end

    it "can customize rescued types" do
      Scientist::Observation::RESCUES.replace [StandardError]

      ex = assert_raises Exception do
        Scientist::Observation.new("test", @experiment) do
          raise Exception.new("not a StandardError")
        end
      end

      assert_equal "not a StandardError", ex.message
    end
  end

  it "compares values" do
    a = Scientist::Observation.new("test", @experiment) { 1 }
    b = Scientist::Observation.new("test", @experiment) { 1 }

    assert a.equivalent_to?(b)

    x = Scientist::Observation.new("test", @experiment) { 1 }
    y = Scientist::Observation.new("test", @experiment) { 2 }

    refute x.equivalent_to?(y)
  end

  it "compares exception messages" do
    a = Scientist::Observation.new("test", @experiment) { raise "error" }
    b = Scientist::Observation.new("test", @experiment) { raise "error" }

    assert a.equivalent_to?(b)

    x = Scientist::Observation.new("test", @experiment) { raise "error" }
    y = Scientist::Observation.new("test", @experiment) { raise "ERROR" }

    refute x.equivalent_to?(y)
  end

  FirstError = Class.new(StandardError)
  SecondError = Class.new(StandardError)

  it "compares exception classes" do
    x = Scientist::Observation.new("test", @experiment) { raise FirstError, "error" }
    y = Scientist::Observation.new("test", @experiment) { raise SecondError, "error" }
    z = Scientist::Observation.new("test", @experiment) { raise FirstError, "error" }

    assert x.equivalent_to?(z)
    refute x.equivalent_to?(y)
  end

  it "compares values using a comparator proc" do
    a = Scientist::Observation.new("test", @experiment) { 1 }
    b = Scientist::Observation.new("test", @experiment) { "1" }

    refute a.equivalent_to?(b)

    compare_on_string = -> (x, y) { x.to_s == y.to_s }

    assert a.equivalent_to?(b, compare_on_string)

    yielded = []
    compare_appends = -> (x, y) do
      yielded << x
      yielded << y
      true
    end
    a.equivalent_to?(b, compare_appends)

    assert_equal [a.value, b.value], yielded
  end

  it "compares exceptions using an error comparator proc" do
    x = Scientist::Observation.new("test", @experiment) { raise FirstError, "error" }
    y = Scientist::Observation.new("test", @experiment) { raise SecondError, "error" }
    z = Scientist::Observation.new("test", @experiment) { raise FirstError, "ERROR" }

    refute x.equivalent_to?(z)
    refute x.equivalent_to?(y)

    compare_on_class = -> (error, other_error) {
      error.class == other_error.class
    }
    compare_on_message = -> (error, other_error) {
      error.message == other_error.message
    }

    assert x.equivalent_to?(z, nil, compare_on_class)
    assert x.equivalent_to?(y, nil, compare_on_message)
  end

  describe "#cleaned_value" do
    it "returns the observation's value by default" do
      a = Scientist::Observation.new("test", @experiment) { 1 }
      assert_equal 1, a.cleaned_value
    end

    it "uses the experiment's clean block to clean a value when configured" do
      @experiment.clean { |value| value.upcase }
      a = Scientist::Observation.new("test", @experiment) { "test" }
      assert_equal "TEST", a.cleaned_value
    end

    it "doesn't clean nil values" do
      @experiment.clean { |value| "foo" }
      a = Scientist::Observation.new("test", @experiment) { nil }
      assert_nil a.cleaned_value
    end

    it "returns false boolean values" do
      a = Scientist::Observation.new("test", @experiment) { false }
      assert_equal false, a.cleaned_value
    end

    it "cleans false values" do
      @experiment.clean { |value| value.to_s.upcase }
      a = Scientist::Observation.new("test", @experiment) { false }
      assert_equal "FALSE", a.cleaned_value
    end
  end

end