Validate Coverage.start parameters

Author: andrykonchin

lib/truffle/coverage.rb

@@ -10,16 +10,27 @@
 # GNU Lesser General Public License version 2.1.
 
 module Coverage
+  UNDEFINED = Object.new
 
   def self.supported?(mode)
     mode == :lines
   end
 
-  def self.start(*arguments, **options)
-    # We have to track if the :lines option was provided, as that calls for a
-    # different result format
-    @lines = !!options[:lines]
+  def self.start(modes = UNDEFINED)
+    if modes == :all || modes == UNDEFINED
+      options = {}
+    else
+      options = Truffle::Type.rb_convert_type(modes, Hash, :to_hash)
+    end
+
+    if options[:lines] && options[:oneshot_lines]
+      raise 'cannot enable lines and oneshot_lines simultaneously'
+    end
+
+    @lines = Primitive.as_boolean(options[:lines]) # presence of :lines affects `result`'s report format
     Truffle::Coverage.enable
+
+    nil
   end
 
   def self.result(stop: true, clear: true)

spec/ruby/library/coverage/start_spec.rb

@@ -2,8 +2,77 @@
 require 'coverage'
 
 describe 'Coverage.start' do
+  before :each do
+    Coverage.should_not.running?
+  end
+
+  after :each do
+    Coverage.result(stop: true, clear: true) if Coverage.running?
+  end
+
+  it "enables the coverage measurement" do
+    Coverage.start
+    Coverage.should.running?
+  end
+
+  it "returns nil" do
+    Coverage.start.should == nil
+  end
+
   ruby_version_is '3.2' do
-    it "can measure coverage within eval" do
+    it "accepts :all optional argument" do
+      Coverage.start(:all)
+      Coverage.should.running?
+    end
+
+    it "accepts lines: optional keyword argument" do
+      Coverage.start(lines: true)
+      Coverage.should.running?
+    end
+
+    it "accepts branches: optional keyword argument" do
+      Coverage.start(branches: true)
+      Coverage.should.running?
+    end
+
+    it "accepts methods: optional keyword argument" do
+      Coverage.start(methods: true)
+      Coverage.should.running?
+    end
+
+    it "accepts eval: optional keyword argument" do
+      Coverage.start(eval: true)
+      Coverage.should.running?
+    end
+
+    it "accepts oneshot_lines: optional keyword argument" do
+      Coverage.start(oneshot_lines: true)
+      Coverage.should.running?
+    end
+
+    it "ignores unknown keyword arguments" do
+      Coverage.start(foo: true)
+      Coverage.should.running?
+    end
+
+    it "expects a Hash if not passed :all" do
+      -> {
+        Coverage.start(42)
+      }.should raise_error(TypeError, "no implicit conversion of Integer into Hash")
+    end
+
+    it "does not accept both lines: and oneshot_lines: keyword arguments" do
+      -> {
+        Coverage.start(lines: true, oneshot_lines: true)
+      }.should raise_error(RuntimeError, "cannot enable lines and oneshot_lines simultaneously")
+    end
+
+    it "enables the coverage measurement if passed options with `false` value" do
+      Coverage.start(lines: false, branches: false, methods: false, eval: false, oneshot_lines: false)
+      Coverage.should.running?
+    end
+
+    it "measures coverage within eval" do
       Coverage.start(lines: true, eval: true)
       eval("Object.new\n"*3, binding, "test.rb", 1)
       Coverage.result["test.rb"].should == {lines: [1, 1, 1]}

spec/tags/library/coverage/start_tags.txt

@@ -1 +1 @@
-fails:Coverage.start can measure coverage within eval
+fails:Coverage.start measures coverage within eval