Implement #guard and #guard_not to combine guards

* Closes #30

lib/mspec/guards/guard.rb

@@ -76,14 +76,22 @@ def yield?(invert = false)
 
   def run_if(name, &block)
     @name = name
-    yield if yield?(false)
+    if block
+      yield if yield?(false)
+    else
+      yield?(false)
+    end
   ensure
     unregister
   end
 
   def run_unless(name, &block)
     @name = name
-    yield if yield?(true)
+    if block
+      yield if yield?(true)
+    else
+      yield?(true)
+    end
   ensure
     unregister
   end
@@ -115,3 +123,19 @@ def match?
     raise "must be implemented by the subclass"
   end
 end
+
+# Combined guards
+
+def guard(condition, &block)
+  raise "condition must be a Proc" unless condition.is_a?(Proc)
+  raise LocalJumpError, "no block given" unless block
+  return yield if MSpec.mode? :unguarded or MSpec.mode? :verify or MSpec.mode? :report
+  yield if condition.call
+end
+
+def guard_not(condition, &block)
+  raise "condition must be a Proc" unless condition.is_a?(Proc)
+  raise LocalJumpError, "no block given" unless block
+  return yield if MSpec.mode? :unguarded or MSpec.mode? :verify or MSpec.mode? :report
+  yield unless condition.call
+end

spec/guards/guard_spec.rb

@@ -195,6 +195,23 @@
     @guard.stub(:match?).and_return(false)
     @guard.run_if(:name) { fail }
   end
+
+  it "returns the result of the block if match? is true" do
+    @guard.stub(:match?).and_return(true)
+    @guard.run_if(:name) { 42 }.should == 42
+  end
+
+  it "returns nil if given a block and match? is false" do
+    @guard.stub(:match?).and_return(false)
+    @guard.run_if(:name) { 42 }.should == nil
+  end
+
+  it "returns what #match? returns when no block is given" do
+    @guard.stub(:match?).and_return(true)
+    @guard.run_if(:name).should == true
+    @guard.stub(:match?).and_return(false)
+    @guard.run_if(:name).should == false
+  end
 end
 
 describe SpecGuard, ".run_unless" do
@@ -213,4 +230,197 @@
     @guard.stub(:match?).and_return(true)
     @guard.run_unless(:name) { fail }
   end
+
+  it "returns the result of the block if match? is false" do
+    @guard.stub(:match?).and_return(false)
+    @guard.run_unless(:name) { 42 }.should == 42
+  end
+
+  it "returns nil if given a block and match? is true" do
+    @guard.stub(:match?).and_return(true)
+    @guard.run_unless(:name) { 42 }.should == nil
+  end
+
+  it "returns the opposite of what #match? returns when no block is given" do
+    @guard.stub(:match?).and_return(true)
+    @guard.run_unless(:name).should == false
+    @guard.stub(:match?).and_return(false)
+    @guard.run_unless(:name).should == true
+  end
+end
+
+describe Object, "#guard" do
+  before :each do
+    ScratchPad.clear
+  end
+
+  after :each do
+    MSpec.clear_modes
+  end
+
+  it "allows to combine guards" do
+    guard1 = VersionGuard.new 'x.x.x'
+    VersionGuard.stub(:new).and_return(guard1)
+    guard2 = PlatformGuard.new :dummy
+    PlatformGuard.stub(:new).and_return(guard2)
+
+    guard1.stub(:match?).and_return(true)
+    guard2.stub(:match?).and_return(true)
+    guard -> { ruby_version_is "2.4" and platform_is :linux } do
+      ScratchPad.record :yield
+    end
+    ScratchPad.recorded.should == :yield
+
+    guard1.stub(:match?).and_return(false)
+    guard2.stub(:match?).and_return(true)
+    guard -> { ruby_version_is "2.4" and platform_is :linux } do
+      fail
+    end
+
+    guard1.stub(:match?).and_return(true)
+    guard2.stub(:match?).and_return(false)
+    guard -> { ruby_version_is "2.4" and platform_is :linux } do
+      fail
+    end
+
+    guard1.stub(:match?).and_return(false)
+    guard2.stub(:match?).and_return(false)
+    guard -> { ruby_version_is "2.4" and platform_is :linux } do
+      fail
+    end
+  end
+
+  it "yields when the Proc returns true" do
+    guard -> { true } do
+      ScratchPad.record :yield
+    end
+    ScratchPad.recorded.should == :yield
+  end
+
+  it "does not yield when the Proc returns false" do
+    guard -> { false } do
+      fail
+    end
+  end
+
+  it "yields if MSpec.mode?(:unguarded) is true" do
+    MSpec.register_mode :unguarded
+
+    guard -> { false } do
+      ScratchPad.record :yield1
+    end
+    ScratchPad.recorded.should == :yield1
+
+    guard -> { true } do
+      ScratchPad.record :yield2
+    end
+    ScratchPad.recorded.should == :yield2
+  end
+
+  it "yields if MSpec.mode?(:verify) is true" do
+    MSpec.register_mode :verify
+
+    guard -> { false } do
+      ScratchPad.record :yield1
+    end
+    ScratchPad.recorded.should == :yield1
+
+    guard -> { true } do
+      ScratchPad.record :yield2
+    end
+    ScratchPad.recorded.should == :yield2
+  end
+
+  it "yields if MSpec.mode?(:report) is true" do
+    MSpec.register_mode :report
+
+    guard -> { false } do
+      ScratchPad.record :yield1
+    end
+    ScratchPad.recorded.should == :yield1
+
+    guard -> { true } do
+      ScratchPad.record :yield2
+    end
+    ScratchPad.recorded.should == :yield2
+  end
+
+  it "raises an error if no Proc is given" do
+    -> { guard :foo }.should raise_error(RuntimeError)
+  end
+
+  it "requires a block" do
+    -> {
+      guard(-> { true })
+    }.should raise_error(LocalJumpError)
+    -> {
+      guard(-> { false })
+    }.should raise_error(LocalJumpError)
+  end
+end
+
+describe Object, "#guard_not" do
+  before :each do
+    ScratchPad.clear
+  end
+
+  it "allows to combine guards" do
+    guard1 = VersionGuard.new 'x.x.x'
+    VersionGuard.stub(:new).and_return(guard1)
+    guard2 = PlatformGuard.new :dummy
+    PlatformGuard.stub(:new).and_return(guard2)
+
+    guard1.stub(:match?).and_return(true)
+    guard2.stub(:match?).and_return(true)
+    guard_not -> { ruby_version_is "2.4" and platform_is :linux } do
+      fail
+    end
+
+    guard1.stub(:match?).and_return(false)
+    guard2.stub(:match?).and_return(true)
+    guard_not -> { ruby_version_is "2.4" and platform_is :linux } do
+      ScratchPad.record :yield1
+    end
+    ScratchPad.recorded.should == :yield1
+
+    guard1.stub(:match?).and_return(true)
+    guard2.stub(:match?).and_return(false)
+    guard_not -> { ruby_version_is "2.4" and platform_is :linux } do
+      ScratchPad.record :yield2
+    end
+    ScratchPad.recorded.should == :yield2
+
+    guard1.stub(:match?).and_return(false)
+    guard2.stub(:match?).and_return(false)
+    guard_not -> { ruby_version_is "2.4" and platform_is :linux } do
+      ScratchPad.record :yield3
+    end
+    ScratchPad.recorded.should == :yield3
+  end
+
+  it "yields when the Proc returns false" do
+    guard_not -> { false } do
+      ScratchPad.record :yield
+    end
+    ScratchPad.recorded.should == :yield
+  end
+
+  it "does not yield when the Proc returns true" do
+    guard_not -> { true } do
+      fail
+    end
+  end
+
+  it "raises an error if no Proc is given" do
+    -> { guard_not :foo }.should raise_error(RuntimeError)
+  end
+
+  it "requires a block" do
+    -> {
+      guard_not(-> { true })
+    }.should raise_error(LocalJumpError)
+    -> {
+      guard_not(-> { false })
+    }.should raise_error(LocalJumpError)
+  end
 end

spec/guards/platform_spec.rb

@@ -20,6 +20,13 @@
     ScratchPad.recorded.should == :yield
   end
 
+  it "returns what #os? returns when no block is given" do
+    PlatformGuard.stub(:os?).and_return(true)
+    platform_is(:solarce).should == true
+    PlatformGuard.stub(:os?).and_return(false)
+    platform_is(:solarce).should == false
+  end
+
   it "sets the name of the guard to :platform_is" do
     platform_is(:solarce) { }
     @guard.name.should == :platform_is
@@ -53,6 +60,13 @@
     ScratchPad.recorded.should == :yield
   end
 
+  it "returns the opposite of what #os? returns when no block is given" do
+    PlatformGuard.stub(:os?).and_return(true)
+    platform_is_not(:solarce).should == false
+    PlatformGuard.stub(:os?).and_return(false)
+    platform_is_not(:solarce).should == true
+  end
+
   it "sets the name of the guard to :platform_is_not" do
     platform_is_not(:solarce) { }
     @guard.name.should == :platform_is_not

spec/guards/version_spec.rb

@@ -68,6 +68,13 @@
     ScratchPad.recorded.should_not == :yield
   end
 
+  it "returns what #match? returns when no block is given" do
+    @guard.stub(:match?).and_return(true)
+    ruby_version_is('x.x.x').should == true
+    @guard.stub(:match?).and_return(false)
+    ruby_version_is('x.x.x').should == false
+  end
+
   it "sets the name of the guard to :ruby_version_is" do
     ruby_version_is("") { }
     @guard.name.should == :ruby_version_is