case_spec.rb

require File.expand_path('../../spec_helper', __FILE__)

describe "The 'case'-construct" do
  it "evaluates the body of the when clause matching the case target expression" do
    case 1
      when 2; false
      when 1; true
    end.should == true
  end

  it "evaluates the body of the when clause whose array expression includes the case target expression" do
    case 2
      when 3, 4; false
      when 1, 2; true
    end.should == true
  end

  it "evaluates the body of the when clause in left-to-right order if it's an array expression" do
    @calls = []
    def foo; @calls << :foo; end
    def bar; @calls << :bar; end

    case true
      when foo, bar;
    end

    @calls.should == [:foo, :bar]
  end

  it "evaluates the body of the when clause whose range expression includes the case target expression" do
    case 5
      when 21..30; false
      when 1..20; true
    end.should == true
  end

  it "returns nil when no 'then'-bodies are given" do
    case "a"
      when "a"
      when "b"
    end.should == nil
  end

  it "evaluates the 'else'-body when no other expression matches" do
    case "c"
      when "a"; 'foo'
      when "b"; 'bar'
      else 'zzz'
    end.should == 'zzz'
  end

  it "returns nil when no expression matches and 'else'-body is empty" do
    case "c"
      when "a"; "a"
      when "b"; "b"
      else
    end.should == nil
  end

  it "returns 2 when a then body is empty" do
    case Object.new
    when Numeric then
      1
    when String then
      # ok
    else
      2
    end.should == 2
  end

  it "returns the statement following 'then'" do
    case "a"
      when "a" then 'foo'
      when "b" then 'bar'
    end.should == 'foo'
  end

  it "tests classes with case equality" do
    case "a"
      when String
        'foo'
      when Symbol
        'bar'
    end.should == 'foo'
  end

  it "tests with matching regexps" do
    case "hello"
      when /abc/; false
      when /^hell/; true
    end.should == true
  end

  it "does not test with equality when given classes" do
    case :symbol.class
      when Symbol
        "bar"
      when String
        "bar"
      else
        "foo"
    end.should == "foo"
  end

  it "takes lists of values" do
    case 'z'
      when 'a', 'b', 'c', 'd'
        "foo"
      when 'x', 'y', 'z'
        "bar"
    end.should == "bar"

    case 'b'
      when 'a', 'b', 'c', 'd'
        "foo"
      when 'x', 'y', 'z'
        "bar"
    end.should == "foo"
  end

  it "expands arrays to lists of values" do
    case 'z'
      when *['a', 'b', 'c', 'd']
        "foo"
      when *['x', 'y', 'z']
        "bar"
    end.should == "bar"
  end

  it "takes an expanded array in addition to a list of values" do
    case 'f'
      when 'f', *['a', 'b', 'c', 'd']
        "foo"
      when *['x', 'y', 'z']
        "bar"
    end.should == "foo"

    case 'b'
      when 'f', *['a', 'b', 'c', 'd']
        "foo"
      when *['x', 'y', 'z']
        "bar"
    end.should == "foo"
  end

  # MR: critical
  it "concats arrays before expanding them" do
    a = ['a', 'b', 'c', 'd']
    b = ['f']

    case 'f'
      when 'f', *a|b
        "foo"
      when *['x', 'y', 'z']
        "bar"
    end.should == "foo"
  end

  it "never matches when clauses with no values" do
    case nil
      when *[]
        "foo"
    end.should == nil
  end

  it "lets you define a method after the case statement" do
    case (def foo; 'foo'; end; 'f')
      when 'a'
        'foo'
      when 'f'
        'bar'
    end.should == 'bar'
  end

  it "raises a SyntaxError when 'else' is used when no 'when' is given" do
    lambda {
      eval <<-CODE
      case 4
        else
          true
      end
      CODE
    }.should raise_error(SyntaxError)
  end

  it "raises a SyntaxError when 'else' is used before a 'when' was given" do
    lambda {
      eval <<-CODE
      case 4
        else
          true
        when 4; false
      end
      CODE
    }.should raise_error(SyntaxError)
  end

  it "supports nested case statements" do
    result = false
    case :x
    when Symbol
      case :y
      when Symbol
        result = true
      end
    end
    result.should == true
  end

  it "supports nested case statements followed by a when with a splatted array" do
    result = false
    case :x
    when Symbol
      case :y
      when Symbol
        result = true
      end
    when *[Symbol]
      result = false
    end
    result.should == true
  end

  it "supports nested case statements followed by a when with a splatted non-array" do
    result = false
    case :x
    when Symbol
      case :y
      when Symbol
        result = true
      end
    when *Symbol
      result = false
    end
    result.should == true
  end

  it "works even if there's only one when statement" do
    case 1
    when 1
      100
    end.should == 100
  end
end

describe "The 'case'-construct with no target expression" do
  it "evaluates the body of the first clause when at least one of its condition expressions is true" do
    case
      when true, false; 'foo'
    end.should == 'foo'
  end

  it "evaluates the body of the first when clause that is not false/nil" do
    case
      when false; 'foo'
      when 2; 'bar'
      when 1 == 1; 'baz'
    end.should == 'bar'

    case
      when false; 'foo'
      when nil; 'foo'
      when 1 == 1; 'bar'
    end.should == 'bar'
  end

  it "evaluates the body of the else clause if all when clauses are false/nil" do
    case
      when false; 'foo'
      when nil; 'foo'
      when 1 == 2; 'bar'
      else 'baz'
    end.should == 'baz'
  end

  it "evaluates multiple conditional expressions as a boolean disjunction" do
    case
      when true, false; 'foo'
      else 'bar'
    end.should == 'foo'

    case
      when false, true; 'foo'
      else 'bar'
    end.should == 'foo'
  end

  it "evaluates true as only 'true' when true is the first clause" do
    case 1
      when true; "bad"
      when Integer; "good"
    end.should == "good"
  end

  it "evaluates false as only 'false' when false is the first clause" do
    case nil
      when false; "bad"
      when nil; "good"
    end.should == "good"
  end

  it "treats a literal array as its own when argument, rather than a list of arguments" do
    case 'foo'
    when ['foo', 'foo']; 'bad'
    when 'foo'; 'good'
    end.should == 'good'
  end
end

language_version __FILE__, "case"