Accept multiline block in an assertion (WIP)

lib/power_assert/parser.rb

@@ -8,9 +8,14 @@ class Parser
 
     def initialize(line, path, lineno, binding, assertion_method_name = nil, assertion_proc = nil)
       @line = line
-      @line_for_parsing = valid_syntax?(line) ? line : slice_expression(line)
       @path = path
       @lineno = lineno
+      begin
+        @rest_lines = open(path).each_line.drop(lineno + 1)
+      rescue StandardError
+        @rest_lines = []
+      end
+      @line_for_parsing = valid_syntax? ? @line : slice_expression(line)
       @binding = binding
       @proc_local_variables = binding.eval('local_variables').map(&:to_s)
       @assertion_method_name = assertion_method_name
@@ -32,16 +37,28 @@ def method_id_set
 
     private
 
-    def valid_syntax?(str)
+    def valid_syntax?
       return true unless defined?(RubyVM)
       begin
         verbose, $VERBOSE = $VERBOSE, nil
-        RubyVM::InstructionSequence.compile(str)
-        true
-      rescue SyntaxError
-        false
+        original_stderr = $stderr.clone
+        $stderr.reopen(File.new('/dev/null', 'w'))
+        while true do
+          begin
+            RubyVM::InstructionSequence.compile(@line)
+            return true
+          rescue SyntaxError
+            if @rest_lines.empty?
+              return false
+            else
+              next_line = @rest_lines.shift
+              @line = "#{@line}#{next_line}"
+            end
+          end
+        end
       ensure
         $VERBOSE = verbose
+        $stderr.reopen(original_stderr)
       end
     end
 

test/fixtures/invalid_multiline_assertion.rb

@@ -0,0 +1,2 @@
+a(0,
+  1,

test/fixtures/valid_multiline_assertion.rb

@@ -0,0 +1,2 @@
+a(0,
+  1)

test/parser_multiline_test.rb

@@ -0,0 +1,30 @@
+class TestParserMultiline < Test::Unit::TestCase
+  def setup
+    ::PowerAssert.public_constant :Parser
+  end
+
+  def teardown
+    ::PowerAssert.private_constant :Parser
+  end
+
+  def test_valid
+    path   = "#{File.dirname(__FILE__)}/fixtures/valid_multiline_assertion.rb"
+    lineno = 0
+    line   = open(path).each_line.first
+    assert parsed_as_valid_syntax?(line, path, lineno)
+  end
+
+  def test_invalid
+    path   = "#{File.dirname(__FILE__)}/fixtures/invalid_multiline_assertion.rb"
+    lineno = 0
+    line   = open(path).each_line.first
+    assert_false parsed_as_valid_syntax?(line, path, lineno)
+  end
+
+  private
+
+  def parsed_as_valid_syntax?(line, path, lineno)
+    parser = ::PowerAssert::Parser.new(line, path, lineno, TOPLEVEL_BINDING, nil, nil)
+    parser.send(:valid_syntax?)
+  end
+end