Merge pull request rails#51006 from kddnewton/parse-with-prism

Parse tests with prism

Author: eileencodes

railties/lib/rails/test_unit/test_parser.rb

@@ -1,5 +1,50 @@
 # frozen_string_literal: true
 
+begin
+  require "prism"
+rescue LoadError
+  # If Prism isn't available (because of using an older Ruby version) then we'll
+  # define a fallback parser using ripper.
+end
+
+if defined?(Prism)
+  module Rails
+    module TestUnit
+      # Parse a test file to extract the line ranges of all tests in both
+      # method-style (def test_foo) and declarative-style (test "foo" do)
+      module TestParser
+        # Helper to translate a method object into the path and line range where
+        # the method was defined.
+        def self.definition_for(method)
+          filepath, start_line = method.source_location
+          queue = [Prism.parse_file(filepath).value]
+
+          while (node = queue.shift)
+            case node.type
+            when :def_node
+              if node.name.start_with?("test") && node.location.start_line == start_line
+                return [filepath, start_line..node.location.end_line]
+              end
+            when :call_node
+              if node.name == :test && node.location.start_line == start_line
+                return [filepath, start_line..node.location.end_line]
+              end
+            end
+
+            queue.concat(node.compact_child_nodes)
+          end
+
+          nil
+        end
+      end
+    end
+  end
+
+  # If we have Prism, then we don't need to define the fallback parser using
+  # ripper.
+  return
+end
+
 require "ripper"
 
 module Rails

railties/test/test_unit/test_parser_test.rb

@@ -1,58 +1,65 @@
 # frozen_string_literal: true
 
+require "active_support/deprecator"
 require "active_support/test_case"
 require "active_support/testing/autorun"
 require "rails/test_unit/test_parser"
 
-class TestParserTest < ActiveSupport::TestCase
-  def test_parser
-    example_test = <<~RUBY
-      require "test_helper"
+class TestParserTestFixture < ActiveSupport::TestCase
+  def test_method
+    assert true
 
-      class ExampleTest < ActiveSupport::TestCase
-        def test_method
-          assert true
+    assert true
+  end
 
+  def test_oneline; assert true; end
 
-        end
+  test "declarative" do
+    assert true
+
+    assert true
+  end
 
-        def test_oneline; assert true; end
+  test("declarative w/parens") do
+    assert true
+  end
 
-        test "declarative" do
-          assert true
-        end
+  self.test "declarative explicit receiver" do
+    assert true
 
-        test("declarative w/parens") do
-          assert true
+    assert true
+  end
 
-        end
+  test("declarative oneline") { assert true }
 
-        self.test "declarative explicit receiver" do
-          assert true
-        end
+  test("declarative oneline do") do assert true end
 
-        test("declarative oneline") { assert true }
+  test("declarative multiline w/ braces") {
+    assert true
+    assert_not false
+  }
+end
 
-        test("declarative oneline do") do assert true end
+class TestParserTest < ActiveSupport::TestCase
+  def test_parser
+    actual =
+      TestParserTestFixture
+        .instance_methods(false)
+        .map { |method| TestParserTestFixture.instance_method(method) }
+        .sort_by { |method| method.source_location[1] }
+        .map { |method| [method.name, *Rails::TestUnit::TestParser.definition_for(method)] }
 
-        test("declarative multiline w/ braces") {
-          assert true
-          refute false
-        }
-      end
-    RUBY
+    expected = [
+      [:test_method, __FILE__, 9..13],
+      [:test_oneline, __FILE__, 15..15],
+      [:test_declarative, __FILE__, 17..21],
+      [:"test_declarative_w/parens", __FILE__, 23..25],
+      [:test_declarative_explicit_receiver, __FILE__, 27..31],
+      [:test_declarative_oneline, __FILE__, 33..33],
+      [:test_declarative_oneline_do, __FILE__, 35..35],
+      [:"test_declarative_multiline_w/_braces", __FILE__, 37..40]
+    ]
 
-    parser = Rails::TestUnit::TestParser.new(example_test, "example_test.rb")
-    expected_map = {
-      4 => 8,   # test_method
-      10 => 10, # test_oneline
-      12 => 14, # declarative
-      16 => 19, # declarative w/parens
-      21 => 23, # declarative explicit receiver
-      25 => 25, # declarative oneline
-      27 => 27, # declarative oneilne do
-      29 => 32  # declarative multiline w/braces
-    }
-    assert_equal expected_map, parser.parse
+    assert_equal expected, actual
   end
 end