diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index f80754f..8b0af91 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -4257,4 +4257,73 @@
   call v9.CheckLegacyAndVim9Success(lines)
 endfunc
 
+" Tests for the str2blob() function
+func Test_str2blob()
+  let lines =<< trim END
+    call assert_equal(0z, str2blob(""))
+    call assert_fails("call str2blob([])", 'E1174: String required for argument 1')
+    call assert_equal(0z6162, str2blob("ab"))
+    call assert_equal(0zC2ABC2BB, str2blob("«»"))
+    call assert_equal(0zC59DC59F, str2blob("ŝş"))
+    call assert_equal(0zE0AE85E0.AE87, str2blob("அஇ"))
+    call assert_equal(0zF09F81B0.F09F81B3, str2blob("🁰🁳"))
+    call assert_equal(0z616263, str2blob('abc', {}))
+    call assert_equal(0zABBB, str2blob('«»', {'encoding': 'latin1'}))
+    call assert_equal(0zC2ABC2BB, str2blob('«»', {'encoding': 'utf8'}))
+
+    call assert_fails("call str2blob('abc', [])", 'E1206: Dictionary required for argument 2')
+    call assert_fails("call str2blob('abc', {'encoding': []})", 'E730: Using a List as a String')
+    call assert_fails("call str2blob('abc', {'encoding': 'ab12xy'})", 'E1515: Unable to convert to ''ab12xy'' encoding')
+    call assert_fails("call str2blob('ŝş', {'encoding': 'latin1'})", 'E1515: Unable to convert to ''latin1'' encoding')
+    call assert_fails("call str2blob('அஇ', {'encoding': 'latin1'})", 'E1515: Unable to convert to ''latin1'' encoding')
+    call assert_fails("call str2blob('🁰🁳', {'encoding': 'latin1'})", 'E1515: Unable to convert to ''latin1'' encoding')
+  END
+  call v9.CheckLegacyAndVim9Success(lines)
+endfunc
+
+" Tests for the blob2str() function
+func Test_blob2str()
+  let lines =<< trim END
+    call assert_equal("", blob2str(0z))
+    call assert_fails("call blob2str([])", 'E1238: Blob required for argument 1')
+    call assert_equal("ab", blob2str(0z6162))
+    call assert_equal("«»", blob2str(0zC2ABC2BB))
+    call assert_equal("ŝş", blob2str(0zC59DC59F))
+    call assert_equal("அஇ", blob2str(0zE0AE85E0.AE87))
+    call assert_equal("🁰🁳", blob2str(0zF09F81B0.F09F81B3))
+    call assert_equal('«»', blob2str(0zABBB, {'encoding': 'latin1'}))
+    call assert_equal('«»', blob2str(0zC2ABC2BB, {'encoding': 'utf8'}))
+
+    #" Invalid encoding
+    call assert_fails("call blob2str(0z80)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0zC0)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0zE0)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0zF0)", "E1515: Unable to convert from 'utf-8' encoding")
+
+    call assert_fails("call blob2str(0z6180)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0z61C0)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0z61E0)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0z61F0)", "E1515: Unable to convert from 'utf-8' encoding")
+
+    call assert_fails("call blob2str(0zC0C0)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0z61C0C0)", "E1515: Unable to convert from 'utf-8' encoding")
+
+    call assert_fails("call blob2str(0zE0)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0zE080)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0zE080C0)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0z61E080C0)", "E1515: Unable to convert from 'utf-8' encoding")
+
+    call assert_fails("call blob2str(0zF08080C0)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0z61F08080C0)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0zF0)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0zF080)", "E1515: Unable to convert from 'utf-8' encoding")
+    call assert_fails("call blob2str(0zF08080)", "E1515: Unable to convert from 'utf-8' encoding")
+
+    call assert_fails("call blob2str(0z6162, [])", 'E1206: Dictionary required for argument 2')
+    call assert_fails("call blob2str(0z6162, {'encoding': []})", 'E730: Using a List as a String')
+    call assert_fails("call blob2str(0z6162, {'encoding': 'ab12xy'})", 'E1515: Unable to convert from ''ab12xy'' encoding')
+  END
+  call v9.CheckLegacyAndVim9Success(lines)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab