diff --git a/src/testdir/test_assert.vim b/src/testdir/test_assert.vim
index 29c8534..0de6ceb 100644
--- a/src/testdir/test_assert.vim
+++ b/src/testdir/test_assert.vim
@@ -25,6 +25,41 @@
   call remove(v:errors, 0)
 endfunc
 
+func Test_assert_equalfile()
+  call assert_equalfile('abcabc', 'xyzxyz')
+  call assert_match("E485: Can't read file abcabc", v:errors[0])
+  call remove(v:errors, 0)
+
+  let goodtext = ["one", "two", "three"]
+  call writefile(goodtext, 'Xone')
+  call assert_equalfile('Xone', 'xyzxyz')
+  call assert_match("E485: Can't read file xyzxyz", v:errors[0])
+  call remove(v:errors, 0)
+
+  call writefile(goodtext, 'Xtwo')
+  call assert_equalfile('Xone', 'Xtwo')
+
+  call writefile([goodtext[0]], 'Xone')
+  call assert_equalfile('Xone', 'Xtwo')
+  call assert_match("first file is shorter", v:errors[0])
+  call remove(v:errors, 0)
+
+  call writefile(goodtext, 'Xone')
+  call writefile([goodtext[0]], 'Xtwo')
+  call assert_equalfile('Xone', 'Xtwo')
+  call assert_match("second file is shorter", v:errors[0])
+  call remove(v:errors, 0)
+
+  call writefile(['1234X89'], 'Xone')
+  call writefile(['1234Y89'], 'Xtwo')
+  call assert_equalfile('Xone', 'Xtwo')
+  call assert_match("difference at byte 4", v:errors[0])
+  call remove(v:errors, 0)
+
+  call delete('Xone')
+  call delete('Xtwo')
+endfunc
+
 func Test_assert_notequal()
   let n = 4
   call assert_notequal('foo', n)