Make Expect.isNotEmpty accept whitespace strings (#452)

Close #428

Author: ratsclub

Expecto.Tests/Tests.fs

@@ -849,6 +849,10 @@ let expecto =
         testCase "when string is empty" (fun _ ->
           Expect.isNotEmpty "" "should fail because string is empty"
         ) |> assertTestFails
+
+        testCase "when string is whitespace" (fun _ ->
+          Expect.isNotEmpty "             " "should pass because string is whitespace"
+        )
       ]
 
       testList "string isnotwhitespace" [
@@ -858,10 +862,6 @@ let expecto =
         testCase "when string is empty" (fun _ ->
           Expect.isNotEmpty "" "should fail because string is empty"
         ) |> assertTestFails
-
-        testCase "when string is whitespace" (fun _ ->
-          Expect.isNotEmpty "             " "should fail because string is whitespace"
-        ) |> assertTestFails
       ]
 
       testList "string matches pattern for isMatch" [

Expecto/Expect.fs

@@ -260,7 +260,7 @@ let isNotInfinity actual message =
 /// Expect the passed string not to be empty.
 let isNotEmpty (actual : string) message =
   isNotNull actual message
-  if String.IsNullOrWhiteSpace actual then Tests.failtestf "%s. Should not be empty." message
+  if String.IsNullOrEmpty actual then Tests.failtestf "%s. Should not be empty." message
 
 /// Expect the passed string is not whitespace
 let isNotWhitespace (actual : string) message =