diff --git a/test/rbi/formatter_test.rb b/test/rbi/formatter_test.rb
index 96f23f20..f0b311c8 100644
--- a/test/rbi/formatter_test.rb
+++ b/test/rbi/formatter_test.rb
@@ -5,6 +5,8 @@
 
 module RBI
   class FormatterTest < Minitest::Test
+    include TestHelper
+
     def test_format_add_sig_templates
       rbi = <<~RBI
         module Foo
@@ -13,7 +15,7 @@ def foo(a, b); end
       RBI
 
       file = File.new
-      file.root = Parser.parse_string(rbi)
+      file.root = parse_rbi(rbi)
 
       out = Formatter.new(add_sig_templates: false).print_file(file)
       assert_equal(rbi, out)
@@ -38,7 +40,7 @@ def bar(a, b); end
       RBI
 
       file = File.new
-      file.root = Parser.parse_string(rbi)
+      file.root = parse_rbi(rbi)
 
       out = Formatter.new(group_nodes: false).print_file(file)
       assert_equal(rbi, out)
@@ -63,7 +65,7 @@ def foo(a, b); end
       RBI
 
       file = File.new
-      file.root = Parser.parse_string(rbi)
+      file.root = parse_rbi(rbi)
 
       out = Formatter.new(max_line_length: nil).print_file(file)
       assert_equal(rbi, out)
@@ -90,7 +92,7 @@ def self.foo; end
       RBI
 
       file = File.new
-      file.root = Parser.parse_string(rbi)
+      file.root = parse_rbi(rbi)
 
       out = Formatter.new(nest_singleton_methods: false).print_file(file)
       assert_equal(rbi, out)
@@ -113,7 +115,7 @@ module Foo
       RBI
 
       file = File.new
-      file.root = Parser.parse_string(rbi)
+      file.root = parse_rbi(rbi)
 
       out = Formatter.new(nest_non_public_methods: false).print_file(file)
       assert_equal(rbi, out)
@@ -137,7 +139,7 @@ def bar(a, b); end
       RBI
 
       file = File.new
-      file.root = Parser.parse_string(rbi)
+      file.root = parse_rbi(rbi)
 
       out = Formatter.new(sort_nodes: false).print_file(file)
       assert_equal(rbi, out)
diff --git a/test/rbi/index_test.rb b/test/rbi/index_test.rb
index ed05f3c0..47cc1ba5 100644
--- a/test/rbi/index_test.rb
+++ b/test/rbi/index_test.rb
@@ -5,6 +5,7 @@
 
 module RBI
   class IndexTest < Minitest::Test
+    include TestHelper
     extend T::Sig
 
     def test_index_empty_trees
@@ -14,7 +15,7 @@ def test_index_empty_trees
     end
 
     def test_index_scopes_and_consts
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         class A
           module B
             module ::C; end
@@ -38,7 +39,7 @@ class << self; end
     end
 
     def test_index_properties
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         class A
           attr_reader :a, :b
           attr_writer :a, :b
@@ -70,7 +71,7 @@ def foo(a); end
     end
 
     def test_index_sorbet_constructs
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         class A < T::Struct
           const :a, Integer
           prop :b, String
@@ -105,7 +106,7 @@ class B < T::Enum
     end
 
     def test_index_multiple_trees
-      tree1 = Parser.parse_string(<<~RBI)
+      tree1 = parse_rbi(<<~RBI)
         class A
           module B
             module ::C; end
@@ -113,7 +114,7 @@ module ::C; end
         end
       RBI
 
-      tree2 = Parser.parse_string(<<~RBI)
+      tree2 = parse_rbi(<<~RBI)
         class A
           module B
             module ::C; end
diff --git a/test/rbi/parser_test.rb b/test/rbi/parser_test.rb
index f8368a20..42125237 100644
--- a/test/rbi/parser_test.rb
+++ b/test/rbi/parser_test.rb
@@ -5,6 +5,8 @@
 
 module RBI
   class ParserTest < Minitest::Test
+    include TestHelper
+
     def test_parse_scopes
       rbi = <<~RBI
         module Foo; end
@@ -14,7 +16,7 @@ class ::Foo::Bar::Baz < ::Foo::Bar; end
         class << self; end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -29,7 +31,7 @@ class << self; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -49,7 +51,7 @@ def m2; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         A = ::Struct.new
         B = ::Struct.new(:a, :b)
@@ -82,7 +84,7 @@ def test_parse_constants
         A::B::C = Foo
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -99,7 +101,7 @@ def test_parse_attributes
         attr_accessor :a, :b, :c
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -110,7 +112,7 @@ def self.m2; end
         def m3(a, b = 42, *c, d:, e: "bar", **f, &g); end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -133,7 +135,7 @@ def test_parse_sigs
         def foo; end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         sig { void }
         sig(:final) { void }
@@ -160,7 +162,7 @@ def test_parse_methods_with_visibility
         private attr_reader :a
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         private def m1; end
         protected def self.m2; end
@@ -180,7 +182,7 @@ class Foo
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -194,7 +196,7 @@ def m2; end
         def m3; end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -209,7 +211,7 @@ def foo; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         class Foo < ::T::Struct
           const :a, A
@@ -233,7 +235,7 @@ def baz; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -247,7 +249,7 @@ def baz; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -262,7 +264,7 @@ class Foo
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -281,7 +283,7 @@ class Foo
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -291,7 +293,7 @@ module Foo; end
         class Bar; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
       assert_equal("-:1:0-2:14", tree.loc.to_s)
     end
 
@@ -303,7 +305,7 @@ class ActiveRecord::Base
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -315,7 +317,7 @@ class Baz < Bar; end
         class << self; end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-1:15
         module Foo; end
@@ -339,7 +341,7 @@ class << self; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-7:3
         module Foo
@@ -363,7 +365,7 @@ class Bar; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-4:3
         Foo = ::Struct.new(:a) do
@@ -383,7 +385,7 @@ def test_parse_constants_locations
         A::B::C = Foo
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-1:8
         Foo = 42
@@ -409,7 +411,7 @@ def test_parse_attributes_locations
         attr_accessor :a, :b, :c
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-1:14
         attr_reader :a
@@ -443,7 +445,7 @@ def m3(a, b = 42, *c, d:, e: "bar", **f, &g); end
         def m4; end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-1:11
         def m1; end
@@ -473,7 +475,7 @@ class Foo
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-4:3
         class Foo
@@ -495,7 +497,7 @@ def m2; end
         def m3; end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-1:6
         public
@@ -523,7 +525,7 @@ def foo; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-7:3
         class Foo < ::T::Struct
@@ -553,7 +555,7 @@ def baz; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-8:3
         class Foo < ::T::Enum
@@ -580,7 +582,7 @@ class Foo
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-7:3
         class Foo
@@ -606,7 +608,7 @@ class Foo
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string(print_locs: true))
         # -:1:0-4:3
         class Foo
@@ -630,7 +632,7 @@ def test_comments_in_empty_files
         # Preserving empty lines
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         # typed: false
         # frozen_string_literal: true
@@ -649,7 +651,7 @@ def test_parse_file_header
 
         module A; end
       RBI
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         # typed: true
 
@@ -664,7 +666,7 @@ def test_parse_file_headers
 
         module A; end
       RBI
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         # typed: true
         # frozen_string_literal: true
@@ -680,7 +682,7 @@ def test_parse_file_header_and_node_comment
         # A comment
         module A; end
       RBI
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         # typed: true
 
@@ -700,7 +702,7 @@ def test_parse_file_header_and_node_comments
         # for the module
         module A; end
       RBI
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         # typed: true
         # frozen_string_literal: true
@@ -731,7 +733,7 @@ def c(a); end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -752,7 +754,7 @@ def baz; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         module A
           # foo comment
@@ -783,7 +785,7 @@ class Bar; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -796,7 +798,7 @@ def bar; end
         end
       RBI
 
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(rbi, out.string)
     end
 
@@ -810,7 +812,7 @@ class B; end
           # A comment 3
         end
       RBI
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         # A comment 1
         # A comment 2
@@ -827,7 +829,7 @@ def test_parse_collect_dangling_file_comments
         module A; end
         # Orphan comment
       RBI
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         module A; end
         # Orphan comment
@@ -847,7 +849,7 @@ def foo(
           e: _
         ); end
       RBI
-      out = Parser.parse_string(rbi)
+      out = parse_rbi(rbi)
       assert_equal(<<~RBI, out.string)
         def bar; end
 
diff --git a/test/rbi/rewriters/annotate_test.rb b/test/rbi/rewriters/annotate_test.rb
index 2fc6b866..5d3e210b 100644
--- a/test/rbi/rewriters/annotate_test.rb
+++ b/test/rbi/rewriters/annotate_test.rb
@@ -5,8 +5,10 @@
 
 module RBI
   class AnnotateTest < Minitest::Test
+    include TestHelper
+
     def test_add_annotation_to_root_nodes
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         module A
           class B
             def m; end
@@ -36,7 +38,7 @@ class C < T::Struct
     end
 
     def test_add_annotation_to_all_scopes
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         module A
           FOO = type_member
 
@@ -78,7 +80,7 @@ class C < T::Struct
     end
 
     def test_add_annotation_to_all_properties
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         # Root scope are always annotated
         module A
           FOO = type_member
@@ -132,7 +134,7 @@ class C < T::Struct
     end
 
     def test_add_annotation_to_all_nodes
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         module A
           FOO = type_member
 
@@ -183,7 +185,7 @@ class C < T::Struct
     end
 
     def test_does_not_reannotate_already_annotated_nodes
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         # @test
         module A
           # @test
@@ -209,7 +211,7 @@ def m1; end
     end
 
     def test_add_different_annotation_to_nodes
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         # @test
         module A
           # @test
diff --git a/test/rbi/rewriters/attr_to_methods_test.rb b/test/rbi/rewriters/attr_to_methods_test.rb
index 7828d51b..c6c5d74e 100644
--- a/test/rbi/rewriters/attr_to_methods_test.rb
+++ b/test/rbi/rewriters/attr_to_methods_test.rb
@@ -5,6 +5,8 @@
 
 module RBI
   class AttrToMethodsTest < Minitest::Test
+    include TestHelper
+
     def test_replaces_attr_reader_with_method
       rbi = Parser.parse_string(<<~RBI)
         # Lorum ipsum...
diff --git a/test/rbi/rewriters/deannotate_test.rb b/test/rbi/rewriters/deannotate_test.rb
index ec27b111..2909baa1 100644
--- a/test/rbi/rewriters/deannotate_test.rb
+++ b/test/rbi/rewriters/deannotate_test.rb
@@ -5,8 +5,10 @@
 
 module RBI
   class AnnotateTest < Minitest::Test
+    include TestHelper
+
     def test_deannotate_nodes
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         # @test
         module A
           # @test
@@ -56,7 +58,7 @@ class C < T::Struct
     end
 
     def test_deannotate_only_removes_the_matching_annotation
-      rbi = Parser.parse_string(<<~RBI)
+      rbi = parse_rbi(<<~RBI)
         # @test
         # @other
         module A
diff --git a/test/rbi/rewriters/filter_versions_test.rb b/test/rbi/rewriters/filter_versions_test.rb
index 5c06e8ae..ab92796c 100644
--- a/test/rbi/rewriters/filter_versions_test.rb
+++ b/test/rbi/rewriters/filter_versions_test.rb
@@ -5,6 +5,8 @@
 
 module RBI
   class FilterVersions < Minitest::Test
+    include TestHelper
+
     def test_filter_versions_do_nothing
       rbi = <<~RBI
         class Foo; end
@@ -13,7 +15,7 @@ class Baz; end
         class Buzz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       Rewriters::FilterVersions.filter(tree, Gem::Version.new("0.4.0"))
       assert_equal(rbi, tree.string)
@@ -34,7 +36,7 @@ class Baz; end
         class Buzz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("0.4.0"))
       assert_equal(<<~RBI, tree.string)
@@ -58,7 +60,7 @@ class Baz; end
         class Buzz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("0.4.0"))
       assert_equal(<<~RBI, tree.string)
@@ -85,7 +87,7 @@ class Baz; end
         class Buzz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("0.4.0"))
       assert_equal(<<~RBI, tree.string)
@@ -109,7 +111,7 @@ class Baz; end
         class Buzz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("0.4.0"))
       assert_equal(<<~RBI, tree.string)
@@ -136,7 +138,7 @@ class Bar; end
         class Baz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("1.1.5"))
       assert_equal(<<~RBI, tree.string)
@@ -160,7 +162,7 @@ class Baz; end
         class Buzz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("0.4.0"))
       assert_equal(<<~RBI, tree.string)
@@ -190,7 +192,7 @@ class Baz; end
         class Buzz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("0.4.0"))
       assert_equal(<<~RBI, tree.string)
@@ -217,7 +219,7 @@ class Baz; end
         class Buzz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("0.4.0-prerelease"))
       assert_equal(<<~RBI, tree.string)
@@ -244,7 +246,7 @@ class Bar; end
         class Baz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("0.4.0"))
       assert_equal(<<~RBI, tree.string)
@@ -272,7 +274,7 @@ class Bar; end
         class Baz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("0.4.0"))
       assert_equal(<<~RBI, tree.string)
@@ -297,7 +299,7 @@ class Bar; end
         class Baz; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       tree.filter_versions!(Gem::Version.new("0.4.0"))
       assert_equal(<<~RBI, tree.string)
@@ -317,7 +319,7 @@ def test_filter_versions_parse_errors
         class Foo; end
       RBI
 
-      tree = Parser.parse_string(rbi)
+      tree = parse_rbi(rbi)
 
       assert_raises(Gem::Requirement::BadRequirementError) do
         tree.filter_versions!(Gem::Version.new("0.4.0"))
diff --git a/test/rbi/rewriters/merge_trees_test.rb b/test/rbi/rewriters/merge_trees_test.rb
index 3337daad..4164593c 100644
--- a/test/rbi/rewriters/merge_trees_test.rb
+++ b/test/rbi/rewriters/merge_trees_test.rb
@@ -5,6 +5,8 @@
 
 module RBI
   class MergeTest < Minitest::Test
+    include TestHelper
+
     def test_merge_empty_trees
       rbi1 = Tree.new
       rbi2 = Tree.new
@@ -13,7 +15,7 @@ def test_merge_empty_trees
     end
 
     def test_merge_empty_tree_into_tree
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class Foo; end
       RBI
 
@@ -28,7 +30,7 @@ class Foo; end
     def test_merge_tree_into_empty_tree
       rbi1 = Tree.new
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class Foo; end
       RBI
 
@@ -39,12 +41,12 @@ class Foo; end
     end
 
     def test_merge_scopes_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A; end
         class B; end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class C; end
         class D; end
       RBI
@@ -59,13 +61,13 @@ class D; end
     end
 
     def test_merge_nested_scopes_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           class B; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class C
           class D; end
         end
@@ -84,13 +86,13 @@ class D; end
     end
 
     def test_merge_same_scopes_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           class B; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           class B; end
           class C; end
@@ -107,14 +109,14 @@ class C; end
     end
 
     def test_merge_constants_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           A = 42
         end
         B = 42
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           A = 42
           B = 42
@@ -134,7 +136,7 @@ class A
     end
 
     def test_merge_attributes_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           attr_reader :a
           attr_writer :a
@@ -144,7 +146,7 @@ class A
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           attr_reader :a
           attr_writer :a
@@ -168,7 +170,7 @@ class A
     end
 
     def test_merge_methods_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           def a; end
           def b; end
@@ -178,7 +180,7 @@ def x(a = T.unsafe(nil), b: T.unsafe(nil)); end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           def a; end
           def b; end
@@ -202,7 +204,7 @@ def e(a); end
     end
 
     def test_merge_mixins_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           include A
           extend B
@@ -212,7 +214,7 @@ class A
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           include A
           extend B
@@ -236,14 +238,14 @@ class A
     end
 
     def test_merge_helpers_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           abstract!
           interface!
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           interface!
           sealed!
@@ -261,14 +263,14 @@ class A
     end
 
     def test_merge_sends_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           foo :bar, :baz
           bar
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           foo :bar, :baz
           baz
@@ -286,14 +288,14 @@ class A
     end
 
     def test_merge_type_members_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           Foo = type_member {{ fixed: Integer }}
           Bar = type_template {{ upper: String }}
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           Foo = type_member {
             { fixed: Integer }
@@ -329,14 +331,14 @@ class A
     end
 
     def test_merge_structs_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A < T::Struct
           prop :a, Integer
           const :b, Integer
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A < T::Struct
           const :b, Integer
           prop :c, Integer
@@ -354,7 +356,7 @@ class A < T::Struct
     end
 
     def test_merge_enums_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A < T::Enum
           enums do
             A = new
@@ -363,7 +365,7 @@ class A < T::Enum
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A < T::Enum
           enums do
             B = new
@@ -385,7 +387,7 @@ class A < T::Enum
     end
 
     def test_merge_signatures
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           def m1; end
 
@@ -405,7 +407,7 @@ def m3; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           sig { returns(Integer) }
           def m1; end
@@ -450,7 +452,7 @@ def m3; end
     end
 
     def test_merge_comments
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         # Comment A1
         class A
           # Comment a1
@@ -460,7 +462,7 @@ def m; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         # Comment A1
         # Comment A2
         # Comment A3
@@ -491,13 +493,13 @@ def m; end
     end
 
     def test_merge_tree_comments_together
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         # typed: true
 
         # Some comments
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         # typed: true
 
         # Other comments
@@ -513,7 +515,7 @@ def test_merge_tree_comments_together
     end
 
     def test_merge_create_conflict_tree_for_scopes
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class Foo
           A = 10
         end
@@ -527,7 +529,7 @@ class Baz < Foo
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         module Foo
           A = 10
         end
@@ -570,7 +572,7 @@ class Baz < Bar
     end
 
     def test_merge_create_conflict_tree_for_structs
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         A = Struct.new(:a) do
           def m; end
         end
@@ -582,7 +584,7 @@ def m; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         A = Struct.new(:a) do
           def m1; end
         end
@@ -622,14 +624,14 @@ def m; end
     end
 
     def test_merge_create_conflict_tree_for_constants
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class Foo
           A = 10
         end
         B = 10
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class Foo
           A = 42
         end
@@ -654,7 +656,7 @@ class Foo
     end
 
     def test_merge_create_conflict_tree_constants_and_scopes
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A; end
         module B; end
         module C; end
@@ -664,7 +666,7 @@ module F; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         module A; end
         class B; end
         C = 42
@@ -702,7 +704,7 @@ module F; end
     end
 
     def test_merge_create_conflict_tree_for_attributes
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class Foo
           attr_accessor :a
           attr_accessor :b
@@ -710,7 +712,7 @@ class Foo
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class Foo
           attr_reader :a
           attr_writer :b
@@ -737,7 +739,7 @@ class Foo
     end
 
     def test_merge_create_conflict_tree_for_methods
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class Foo
           def m1; end
           def m2(a); end
@@ -750,7 +752,7 @@ def m8(a: nil); end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class Foo
           def m1(a); end
           def m2; end
@@ -813,7 +815,7 @@ def m8(a: 10); end
     end
 
     def test_merge_create_conflict_tree_for_mixins
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           include A, B
           extend A, B
@@ -821,7 +823,7 @@ class A
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           include B
           extend B
@@ -846,7 +848,7 @@ class A
     end
 
     def test_merge_create_conflict_tree_for_sends
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A
           foo A
           bar :bar
@@ -854,7 +856,7 @@ class A
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A
           foo B
           bar "bar"
@@ -879,7 +881,7 @@ class A
     end
 
     def test_merge_create_conflict_tree_for_tstructs
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class A < T::Struct
           prop :a, Integer
           const :b, Integer
@@ -888,7 +890,7 @@ class A < T::Struct
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class A < T::Struct
           const :a, Integer
           prop :b, Integer
@@ -916,7 +918,7 @@ class A < T::Struct
     end
 
     def test_merge_create_conflict_tree_for_signatures
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class Foo
           sig { returns(Integer) }
           attr_reader :a
@@ -932,7 +934,7 @@ def m3; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         class Foo
           sig { returns(String) }
           attr_reader :a
@@ -981,14 +983,14 @@ def m3; end
     end
 
     def test_merge_return_the_list_of_conflicts
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         class Foo
           A = 10
         end
         B = 10
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         module Foo
           A = 42
         end
@@ -1005,7 +1007,7 @@ module Foo
     end
 
     def test_merge_keep_left
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         module Foo
           A = 10
 
@@ -1020,7 +1022,7 @@ def m3; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         module Foo
           A = 42
 
@@ -1055,7 +1057,7 @@ def m4; end
     end
 
     def test_merge_keep_right
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         module Foo
           A = 10
 
@@ -1070,7 +1072,7 @@ def m3; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         module Foo
           A = 42
 
@@ -1105,7 +1107,7 @@ def m4; end
     end
 
     def test_merge_trees_with_singleton_classes
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         module Foo
           class << self
             def m1; end
@@ -1116,7 +1118,7 @@ def m2; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         module Foo
           def self.m1(x); end
 
@@ -1140,7 +1142,7 @@ def m2; end
     end
 
     def test_merge_trees_with_singleton_classes_with_scope
-      rbi1 = Parser.parse_string(<<~RBI)
+      rbi1 = parse_rbi(<<~RBI)
         module Foo
           def self.m1(x); end
 
@@ -1149,7 +1151,7 @@ def self.m2; end
         end
       RBI
 
-      rbi2 = Parser.parse_string(<<~RBI)
+      rbi2 = parse_rbi(<<~RBI)
         module Foo
           class << self
             def m1; end
diff --git a/test/rbi/rewriters/remove_known_definitions_test.rb b/test/rbi/rewriters/remove_known_definitions_test.rb
index cd0f8192..64f020a8 100644
--- a/test/rbi/rewriters/remove_known_definitions_test.rb
+++ b/test/rbi/rewriters/remove_known_definitions_test.rb
@@ -5,6 +5,8 @@
 
 module RBI
   class RemoveKnownDefinitionsTest < Minitest::Test
+    include TestHelper
+
     def test_remove_known_definitions_does_nothing_with_an_empty_index
       index = Index.new
 
@@ -20,7 +22,7 @@ def bar; end
         BAZ = 42
       RBI
 
-      original = Parser.parse_string(shim)
+      original = parse_rbi(shim)
       cleaned, operations = Rewriters::RemoveKnownDefinitions.remove(original, index)
 
       assert_equal(shim, cleaned.string)
@@ -28,25 +30,25 @@ def bar; end
     end
 
     def test_remove_known_definitions_removes_all_definitions_found_in_index
-      tree1 = Parser.parse_string(<<~RBI)
+      tree1 = parse_rbi(<<~RBI)
         class Foo
           attr_reader :foo
         end
       RBI
 
-      tree2 = Parser.parse_string(<<~RBI)
+      tree2 = parse_rbi(<<~RBI)
         module Bar
           def bar; end
         end
       RBI
 
-      tree3 = Parser.parse_string(<<~RBI)
+      tree3 = parse_rbi(<<~RBI)
         BAZ = 42
       RBI
 
       index = Index.index(tree1, tree2, tree3)
 
-      shim = Parser.parse_string(<<~RBI)
+      shim = parse_rbi(<<~RBI)
         class Foo
           attr_reader :foo
         end
@@ -72,7 +74,7 @@ def bar; end
     end
 
     def test_remove_known_definitions_keeps_definitions_not_found_in_index
-      tree = Parser.parse_string(<<~RBI)
+      tree = parse_rbi(<<~RBI)
         class Foo
           def foo; end
           FOO = 42
@@ -81,7 +83,7 @@ def foo; end
 
       index = Index.index(tree)
 
-      shim = Parser.parse_string(<<~RBI)
+      shim = parse_rbi(<<~RBI)
         class Foo
           def foo; end
           def bar; end
@@ -106,7 +108,7 @@ def bar; end
     end
 
     def test_remove_known_definitions_keeps_mismatching_definitions
-      tree = Parser.parse_string(<<~RBI)
+      tree = parse_rbi(<<~RBI)
         class Foo
           def foo; end
         end
@@ -121,7 +123,7 @@ def foo; end
 
       index = Index.index(tree)
 
-      shim = Parser.parse_string(<<~RBI)
+      shim = parse_rbi(<<~RBI)
         class Foo
           def foo(x); end
         end
@@ -139,25 +141,25 @@ module Bar; end
     end
 
     def test_remove_known_definitions_removes_empty_scopes
-      tree1 = Parser.parse_string(<<~RBI)
+      tree1 = parse_rbi(<<~RBI)
         class Foo
           attr_reader :foo
         end
       RBI
 
-      tree2 = Parser.parse_string(<<~RBI)
+      tree2 = parse_rbi(<<~RBI)
         class Foo
           def bar; end
         end
       RBI
 
-      tree3 = Parser.parse_string(<<~RBI)
+      tree3 = parse_rbi(<<~RBI)
         Foo::BAZ = 42
       RBI
 
       index = Index.index(tree1, tree2, tree3)
 
-      shim = Parser.parse_string(<<~RBI)
+      shim = parse_rbi(<<~RBI)
         class Foo
           attr_reader :foo
           def bar; end
@@ -178,11 +180,11 @@ def bar; end
     end
 
     def test_remove_known_definitions_keeps_empty_scopes_not_found_in_index
-      tree1 = Parser.parse_string(<<~RBI)
+      tree1 = parse_rbi(<<~RBI)
         class Foo; end
       RBI
 
-      tree2 = Parser.parse_string(<<~RBI)
+      tree2 = parse_rbi(<<~RBI)
         class Bar
           def bar; end
         end
@@ -190,7 +192,7 @@ def bar; end
 
       index = Index.index(tree1, tree2)
 
-      shim = Parser.parse_string(<<~RBI)
+      shim = parse_rbi(<<~RBI)
         class Foo; end
         class Bar
           def bar; end
@@ -212,7 +214,7 @@ class Baz; end
     end
 
     def test_remove_known_definitions_keeps_nodes_defined_with_a_signature
-      tree = Parser.parse_string(<<~RBI)
+      tree = parse_rbi(<<~RBI)
         class Foo
           def foo; end
           def self.bar; end
@@ -222,7 +224,7 @@ def self.bar; end
 
       index = Index.index(tree)
 
-      shim = Parser.parse_string(<<~RBI)
+      shim = parse_rbi(<<~RBI)
         class Foo
           sig { void }
           def foo; end
@@ -242,7 +244,7 @@ def self.bar; end
     end
 
     def test_remove_known_definitions_keeps_multiple_attributes
-      tree = Parser.parse_string(<<~RBI)
+      tree = parse_rbi(<<~RBI)
         class Foo
           attr_reader :foo
         end
@@ -250,7 +252,7 @@ class Foo
 
       index = Index.index(tree)
 
-      shim = Parser.parse_string(<<~RBI)
+      shim = parse_rbi(<<~RBI)
         class Foo
           attr_reader :foo, :bar
         end
@@ -263,7 +265,7 @@ class Foo
     end
 
     def test_remove_known_definitions_even_if_the_comments_differ
-      tree = Parser.parse_string(<<~RBI)
+      tree = parse_rbi(<<~RBI)
         class Foo
           def foo; end
         end
@@ -271,7 +273,7 @@ def foo; end
 
       index = Index.index(tree)
 
-      shim = Parser.parse_string(<<~RBI)
+      shim = parse_rbi(<<~RBI)
         class Foo
           # Some comments
           def foo; end
@@ -289,7 +291,7 @@ def foo; end
     end
 
     def test_remove_known_definitions_even_if_the_value_differ
-      tree = Parser.parse_string(<<~RBI)
+      tree = parse_rbi(<<~RBI)
         class Foo
           FOO = 42
         end
@@ -297,7 +299,7 @@ class Foo
 
       index = Index.index(tree)
 
-      shim = Parser.parse_string(<<~RBI)
+      shim = parse_rbi(<<~RBI)
         class Foo
           FOO = 24
         end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 58cfaccb..c8ce668d 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -11,3 +11,14 @@
 unless ENV["RM_INFO"]
   Minitest::Reporters.use!(Minitest::Reporters::SpecReporter.new(color: true))
 end
+
+module TestHelper
+  extend T::Sig
+
+  private
+
+  sig { params(rbs_string: String).returns(RBI::Tree) }
+  def parse_rbi(rbs_string)
+    RBI::Parser.parse_string(rbs_string)
+  end
+end