diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index aae8b36..027cdc8 100644
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
@@ -668,13 +668,13 @@
   diffthis
   redraw
 
-  call assert_equal(synIDattr(diff_hlID(-1, 1), "name"), "")
+  call diff_hlID(-1, 1)->synIDattr("name")->assert_equal("")
 
-  call assert_equal(synIDattr(diff_hlID(1, 1), "name"), "DiffChange")
-  call assert_equal(synIDattr(diff_hlID(1, 2), "name"), "DiffText")
-  call assert_equal(synIDattr(diff_hlID(2, 1), "name"), "")
-  call assert_equal(synIDattr(diff_hlID(3, 1), "name"), "DiffAdd")
-  call assert_equal(synIDattr(diff_hlID(4, 1), "name"), "")
+  call diff_hlID(1, 1)->synIDattr("name")->assert_equal("DiffChange")
+  call diff_hlID(1, 2)->synIDattr("name")->assert_equal("DiffText")
+  call diff_hlID(2, 1)->synIDattr("name")->assert_equal("")
+  call diff_hlID(3, 1)->synIDattr("name")->assert_equal("DiffAdd")
+  call diff_hlID(4, 1)->synIDattr("name")->assert_equal("")
 
   wincmd w
   call assert_equal(synIDattr(diff_hlID(1, 1), "name"), "DiffChange")
diff --git a/src/testdir/test_method.vim b/src/testdir/test_method.vim
index cc0fe5d..93918c8 100644
--- a/src/testdir/test_method.vim
+++ b/src/testdir/test_method.vim
@@ -46,6 +46,7 @@
   call assert_equal(2, d->get('two'))
   call assert_fails("let x = d->index(2)", 'E897:')
   call assert_fails("let x = d->insert(0)", 'E899:')
+  call assert_true(d->has_key('two'))
   call assert_equal([['one', 1], ['two', 2], ['three', 3]], d->items())
   call assert_fails("let x = d->join()", 'E714:')
   call assert_equal(['one', 'two', 'three'], d->keys())
@@ -65,6 +66,16 @@
   call assert_equal([1, 2, 3], d->values())
 endfunc
 
+func Test_string()
+  call assert_equal(['1', '2', '3'], '1 2 3'->split())
+  call assert_equal([1, 2, 3], '1 2 3'->split()->map({i, v -> str2nr(v)}))
+  call assert_equal([65, 66, 67], 'ABC'->str2list())
+  call assert_equal(3, 'ABC'->strlen())
+  call assert_equal('a^Mb^[c', "a\rb\ec"->strtrans())
+  call assert_equal(4, "aあb"->strwidth())
+  call assert_equal('axc', 'abc'->substitute('b', 'x', ''))
+endfunc
+
 func Test_append()
   new
   eval ['one', 'two', 'three']->append(1)
diff --git a/src/testdir/test_syntax.vim b/src/testdir/test_syntax.vim
index 562a44c..a316ce7 100644
--- a/src/testdir/test_syntax.vim
+++ b/src/testdir/test_syntax.vim
@@ -517,8 +517,8 @@
   call assert_equal([], synstack(1, 1))
 
   norm f/
-  call assert_equal(['cComment', 'cCommentStart'], map(synstack(line("."), col(".")), 'synIDattr(v:val, "name")'))
-  call assert_equal(['Comment', 'Comment'],	   map(synstack(line("."), col(".")), 'synIDattr(synIDtrans(v:val), "name")'))
+  eval synstack(line("."), col("."))->map('synIDattr(v:val, "name")')->assert_equal(['cComment', 'cCommentStart'])
+  eval synstack(line("."), col("."))->map('synIDattr(synIDtrans(v:val), "name")')->assert_equal(['Comment', 'Comment'])
 
   norm fA
   call assert_equal(['cComment'], map(synstack(line("."), col(".")), 'synIDattr(v:val, "name")'))
diff --git a/src/testdir/test_system.vim b/src/testdir/test_system.vim
index 25061ea..f09f509 100644
--- a/src/testdir/test_system.vim
+++ b/src/testdir/test_system.vim
@@ -4,13 +4,13 @@
   if !executable('echo') || !executable('cat') || !executable('wc')
     return
   endif
-  let out = system('echo 123')
+  let out = 'echo 123'->system()
   " On Windows we may get a trailing space.
   if out != "123 \n"
     call assert_equal("123\n", out)
   endif
 
-  let out = systemlist('echo 123')
+  let out = 'echo 123'->systemlist()
   " On Windows we may get a trailing space and CR.
   if out != ["123 \r"]
     call assert_equal(['123'], out)