Apply suggestions from code review.

Author: CaptnCodr

src/FsUnit.NUnit/CustomConstraints.fs

@@ -17,4 +17,4 @@ module CustomConstraints =
                 let result = Common.isOfCase this.Expected actual
                 ConstraintResult(this, actual, result)
             else
-                failwith "Value (not expression) is not a union case."
+                failwith $"Value (not expression) is not a union case. Got a {actual.GetType().Name}."

src/FsUnit.Xunit/CustomMatchers.fs

@@ -185,10 +185,10 @@ let instanceOfType<'a> =
 let contain expected =
     let matches(actual: obj) =
         match actual with
-        | :? list<_> as l -> l |> List.exists(fun i -> i = expected)
-        | :? array<_> as a -> a |> Array.exists(fun i -> i = expected)
-        | :? seq<_> as s -> s |> Seq.exists(fun i -> i = expected)
-        | :? IEnumerable as e -> e |> Seq.cast |> Seq.exists(fun i -> i = expected)
+        | :? list<_> as l -> l |> List.exists((=) expected)
+        | :? array<_> as a -> a |> Array.exists((=) expected)
+        | :? seq<_> as s -> s |> Seq.exists((=) expected)
+        | :? IEnumerable as e -> e |> Seq.cast |> Seq.exists((=) expected)
         | _ -> false
 
     CustomMatcher<obj>($"Contains %A{expected}", Func<_, _> matches)

tests/FsUnit.NUnit.Test/beOfCaseTests.fs

@@ -43,7 +43,7 @@ type ``be ofCase tests``() =
     [<Test>]
     member _.``Given a non-union case as value argument throws an exception``() =
         (fun () -> 5 |> should not' (be ofCase <@ Second 5 @>) |> ignore)
-        |> should (throwWithMessage "Value (not expression) is not a union case.") typeof<System.Exception>
+        |> should (throwWithMessage "Value (not expression) is not a union case. Got a Int32.") typeof<System.Exception>
 
     [<Test>]
     member _.``None should be ofCase None``() =