case_spec.rb

require_relative '../spec_helper'

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 "tests with matching regexps and sets $~ and captures" do
    case "foo42"
    when /oo(\d+)/
      $~.should be_kind_of(MatchData)
      $1.should == "42"
    else
      flunk
    end
    $~.should be_kind_of(MatchData)
    $1.should == "42"
  end

  it "tests with a regexp interpolated within another regexp" do
    digits = '\d+'
    case "foo44"
    when /oo(#{digits})/
      $~.should be_kind_of(MatchData)
      $1.should == "44"
    else
      flunk
    end
    $~.should be_kind_of(MatchData)
    $1.should == "44"
  end

  it "tests with a string interpolated in a regexp" do
    digits_regexp = /\d+/
    case "foo43"
    when /oo(#{digits_regexp})/
      $~.should be_kind_of(MatchData)
      $1.should == "43"
    else
      flunk
    end
    $~.should be_kind_of(MatchData)
    $1.should == "43"
  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 "tests an empty array" do
    case []
    when []
      'foo'
    else
      '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

  it "takes an expanded array before additional listed values" do
    case 'f'
    when *['a', 'b', 'c', 'd'], 'f'
      "foo"
    when *['x', 'y', 'z']
      "bar"
    end.should == 'foo'
  end

  it "expands arrays from variables before additional listed values" do
    a = ['a', 'b', 'c']
    case 'a'
    when *a, 'd', 'e'
      "foo"
    when 'x'
      "bar"
    end.should == "foo"
  end

  it "expands arrays from variables before a single additional listed value" do
    a = ['a', 'b', 'c']
    case 'a'
    when *a, 'd'
      "foo"
    when 'x'
      "bar"
    end.should == "foo"
  end

  it "expands multiple arrays from variables before additional listed values" do
    a = ['a', 'b', 'c']
    b = ['d', 'e', 'f']

    case 'f'
    when *a, *b, 'g', 'h'
      "foo"
    when 'x'
      "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
    -> {
      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
    -> {
      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

  it "takes multiple expanded arrays" do
    a1 = ['f', 'o', 'o']
    a2 = ['b', 'a', 'r']

    case 'f'
    when *a1, *['x', 'y', 'z']
      "foo"
    when *a2, *['x', 'y', 'z']
      "bar"
    end.should == "foo"

    case 'b'
    when *a1, *['x', 'y', 'z']
      "foo"
    when *a2, *['x', 'y', 'z']
      "bar"
    end.should == "bar"
  end

  it "calls === even when private" do
    klass = Class.new do
      def ===(o)
        true
      end
      private :===
    end

    case 1
    when klass.new
      :called
    end.should == :called
  end

  it "accepts complex expressions within ()" do
    case 'a'
    when (raise if 2+2 == 3; /a/)
      :called
    end.should == :called
  end

  # Homogeneous cases are often optimized to avoid === using a jump table, and should be tested separately.
  # See https://github.com/jruby/jruby/issues/6440
  it "handles homogeneous cases" do
    case
    when 1; 'foo'
    when 2; 'bar'
    end.should == 'foo'
  end
end