shard-spectator/spec/spectator/mocks/null_double_spec.cr

require "../../spec_helper"

Spectator.describe Spectator::NullDouble do
  Spectator::NullDouble.define(EmptyDouble)
  Spectator::NullDouble.define(FooBarDouble, "dbl-name", foo: 42, bar: "baz")

  private macro expect_null_double(double, actual)
    %actual_box = Box.box({{actual}})
    %double_box = Box.box({{double}})
    expect(%actual_box).to eq(%double_box), {{actual.stringify}} + " is not " + {{double.stringify}}
  end

  # The subject `dbl` must be carefully used in sub-contexts, otherwise it pollutes parent scopes.
  # This changes the type of `dbl` to `Double`, which produces a union of methods and their return types.
  context "plain double" do
    subject(dbl) { FooBarDouble.new }

    it "responds to defined messages" do
      aggregate_failures do
        expect(dbl.foo).to eq(42)
        expect(dbl.bar).to eq("baz")
      end
    end

    it "returns self on undefined messages" do
      expect_null_double(dbl, dbl.baz)
    end

    it "has a non-union return type" do
      aggregate_failures do
        expect(dbl.foo).to compile_as(Int32)
        expect(dbl.bar).to compile_as(String)
      end
    end

    context "blocks" do
      it "supports blocks" do
        aggregate_failures do
          expect(dbl.foo { nil }).to eq(42)
          expect(dbl.bar { nil }).to eq("baz")
        end
      end

      it "supports blocks and has non-union return types" do
        aggregate_failures do
          expect(dbl.foo { nil }).to compile_as(Int32)
          expect(dbl.bar { nil }).to compile_as(String)
        end
      end

      it "returns self on undefined messages" do
        expect_null_double(dbl, dbl.baz { nil })
      end
    end
  end

  context "with abstract stubs and return type annotations" do
    Spectator::NullDouble.define(TestDouble2) do
      abstract_stub abstract def foo(value) : String
    end

    let(arguments) { Spectator::Arguments.capture(/foo/) }
    let(stub) { Spectator::ValueStub.new(:foo, "bar", arguments).as(Spectator::Stub) }
    subject(dbl) { TestDouble2.new([stub]) }

    it "enforces the return type" do
      expect(dbl.foo("foobar")).to compile_as(String)
    end

    it "raises on non-matching arguments" do
      expect { dbl.foo("bar") }.to raise_error(TypeCastError, /String/)
    end

    it "raises on non-matching stub" do
      stub = Spectator::ValueStub.new(:foo, 42, arguments).as(Spectator::Stub)
      dbl._spectator_define_stub(stub)
      expect { dbl.foo("foobar") }.to raise_error(TypeCastError, /String/)
    end
  end

  context "with nillable return type annotations" do
    Spectator::NullDouble.define(TestDouble) do
      abstract_stub abstract def foo : String?
      abstract_stub abstract def bar : Nil
    end

    let(foo_stub) { Spectator::ValueStub.new(:foo, nil).as(Spectator::Stub) }
    let(bar_stub) { Spectator::ValueStub.new(:bar, nil).as(Spectator::Stub) }
    subject(dbl) { TestDouble.new([foo_stub, bar_stub]) }

    it "doesn't raise on nil" do
      aggregate_failures do
        expect(dbl.foo).to be_nil
        expect(dbl.bar).to be_nil
      end
    end
  end

  context "with common object methods" do
    subject(dbl) do
      EmptyDouble.new([
        Spectator::ValueStub.new(:"!=", "!="),
        Spectator::ValueStub.new(:"!~", "!~"),
        Spectator::ValueStub.new(:"==", "=="),
        Spectator::ValueStub.new(:"===", "==="),
        Spectator::ValueStub.new(:"=~", "=~"),
        Spectator::ValueStub.new(:class, "class"),
        Spectator::ValueStub.new(:dup, "dup"),
        Spectator::ValueStub.new(:hash, "hash"),
        Spectator::ValueStub.new(:"in?", true),
        Spectator::ValueStub.new(:inspect, "inspect"),
        Spectator::ValueStub.new(:itself, "itself"),
        Spectator::ValueStub.new(:"not_nil!", "not_nil!"),
        Spectator::ValueStub.new(:pretty_inspect, "pretty_inspect"),
        Spectator::ValueStub.new(:tap, "tap"),
        Spectator::ValueStub.new(:to_json, "to_json"),
        Spectator::ValueStub.new(:to_pretty_json, "to_pretty_json"),
        Spectator::ValueStub.new(:to_s, "to_s"),
        Spectator::ValueStub.new(:to_yaml, "to_yaml"),
        Spectator::ValueStub.new(:try, "try"),
        Spectator::ValueStub.new(:object_id, 42_u64),
        Spectator::ValueStub.new(:"same?", true),
      ] of Spectator::Stub)
    end

    it "responds with defined messages" do
      aggregate_failures do
        expect(dbl.!=(42)).to eq("!=")
        expect(dbl.!~(42)).to eq("!~")
        expect(dbl.==(42)).to eq("==")
        expect(dbl.===(42)).to eq("===")
        expect(dbl.=~(42)).to eq("=~")
        expect(dbl.class).to eq("class")
        expect(dbl.dup).to eq("dup")
        expect(dbl.hash(42)).to eq("hash")
        expect(dbl.hash).to eq("hash")
        expect(dbl.in?(42)).to eq(true)
        expect(dbl.in?(1, 2, 3)).to eq(true)
        expect(dbl.inspect).to eq("inspect")
        expect(dbl.itself).to eq("itself")
        expect(dbl.not_nil!).to eq("not_nil!")
        expect(dbl.pretty_inspect).to eq("pretty_inspect")
        expect(dbl.tap { nil }).to eq("tap")
        expect(dbl.to_json).to eq("to_json")
        expect(dbl.to_pretty_json).to eq("to_pretty_json")
        expect(dbl.to_s).to eq("to_s")
        expect(dbl.to_yaml).to eq("to_yaml")
        expect(dbl.try { nil }).to eq("try")
        expect(dbl.object_id).to eq(42_u64)
        expect(dbl.same?(dbl)).to eq(true)
        expect(dbl.same?(nil)).to eq(true)
      end
    end

    it "has a non-union return type" do
      expect(dbl.inspect).to compile_as(String)
    end
  end

  context "without common object methods" do
    subject(dbl) { EmptyDouble.new }

    it "returns self with undefined messages" do
      io = IO::Memory.new
      pp = PrettyPrint.new(io)
      aggregate_failures do
        # Methods that would cause type cast errors are omitted from this list.
        expect_null_double(dbl, dbl.!=(42))
        expect_null_double(dbl, dbl.!~(42))
        expect_null_double(dbl, dbl.==(42))
        expect_null_double(dbl, dbl.===(42))
        expect_null_double(dbl, dbl.=~(42))
        expect_null_double(dbl, dbl.class)
        expect_null_double(dbl, dbl.dup)
        expect_null_double(dbl, dbl.hash(42))
        expect_null_double(dbl, dbl.hash)
        expect_null_double(dbl, dbl.itself)
        expect_null_double(dbl, dbl.not_nil!)
        expect_null_double(dbl, dbl.tap { nil })
        expect_null_double(dbl, dbl.try { nil })
      end
    end
  end

  context "with arguments constraints" do
    let(arguments) { Spectator::Arguments.capture(/foo/) }

    context "without common object methods" do
      Spectator::NullDouble.define(TestDouble) do
        abstract_stub abstract def foo(value)
        abstract_stub abstract def foo(value, & : -> _)
      end

      let(stub) { Spectator::ValueStub.new(:foo, "bar", arguments).as(Spectator::Stub) }
      subject(dbl) { TestDouble.new([stub]) }

      it "returns the response when constraint satisfied" do
        expect(dbl.foo("foobar")).to eq("bar")
      end

      it "returns self when constraint unsatisfied" do
        expect_null_double(dbl, dbl.foo("baz"))
      end

      it "returns self when argument count doesn't match" do
        expect_null_double(dbl, dbl.foo)
      end

      it "ignores the block argument if not in the constraint" do
        expect(dbl.foo("foobar") { nil }).to eq("bar")
      end
    end

    context "with common object methods" do
      Spectator::NullDouble.define(TestDouble) do
        stub abstract def hash(hasher)
      end

      let(stub) { Spectator::ValueStub.new(:hash, 12345, arguments).as(Spectator::Stub) }
      subject(dbl) { TestDouble.new([stub]) }

      it "returns the response when constraint satisfied" do
        expect(dbl.hash("foobar")).to eq(12345)
      end

      it "returns self when constraint unsatisfied" do
        expect_null_double(dbl, dbl.hash("baz"))
      end

      it "returns self when argument count doesn't match" do
        expect_null_double(dbl, dbl.hash)
      end
    end
  end

  describe "#_spectator_define_stub" do
    subject(dbl) { FooBarDouble.new }
    let(stub3) { Spectator::ValueStub.new(:foo, 3) }
    let(stub5) { Spectator::ValueStub.new(:foo, 5) }
    let(stub7) { Spectator::ValueStub.new(:foo, 7, Spectator::Arguments.capture(:lucky)) }

    it "overrides an existing method" do
      expect { dbl._spectator_define_stub(stub3) }.to change { dbl.foo }.from(42).to(3)
    end

    it "replaces an existing stub" do
      dbl._spectator_define_stub(stub3)
      expect { dbl._spectator_define_stub(stub5) }.to change { dbl.foo }.from(3).to(5)
    end

    it "doesn't affect other methods" do
      expect { dbl._spectator_define_stub(stub5) }.to_not change { dbl.bar }
    end

    it "picks the correct stub based on arguments" do
      dbl._spectator_define_stub(stub5)
      dbl._spectator_define_stub(stub7)
      aggregate_failures do
        expect(dbl.foo).to eq(5)
        expect(dbl.foo(:lucky)).to eq(7)
      end
    end

    it "only uses a stub if an argument constraint is met" do
      dbl._spectator_define_stub(stub7)
      aggregate_failures do
        expect(dbl.foo).to eq(42)
        expect(dbl.foo(:lucky)).to eq(7)
      end
    end

    it "ignores the block argument if not in the constraint" do
      dbl._spectator_define_stub(stub5)
      dbl._spectator_define_stub(stub7)
      aggregate_failures do
        expect(dbl.foo { nil }).to eq(5)
        expect(dbl.foo(:lucky) { nil }).to eq(7)
      end
    end
  end
end