Add unit tests for Result and a few utility methods & fix edge case in StringUtils

Core/Utils/StringUtils.cs

@@ -28,10 +28,14 @@ public static string ConvertRot13(string str){
         }
 
         public static int CountOccurrences(string source, string substring){
-            int count = 0, index = 0;
+            if (substring.Length == 0){
+                throw new ArgumentOutOfRangeException(nameof(substring), "Searched substring must not be empty.");
+            }
+
+            int count = 0, index = 0, length = substring.Length;
 
             while((index = source.IndexOf(substring, index)) != -1){
-                index += substring.Length;
+                index += length;
                 ++count;
             }
 

lib/TweetTest.Unit/Core/TestStringUtils.fs

@@ -75,4 +75,44 @@ module ConvertPascalCaseToScreamingSnakeCase =
         Assert.Equal("I_LIKE_HTML_AND_CSS", StringUtils.ConvertPascalCaseToScreamingSnakeCase("ILikeHTMLAndCSS"))
 
 
-// TODO add new tests
+module ConvertRot13 =
+        
+    [<Fact>]
+    let ``ignores digits and special characters`` () =
+        Assert.Equal("<123'456.789>", StringUtils.ConvertRot13("<123'456.789>"))
+
+    [<Fact>]
+    let ``converts lowercase letters correctly`` () =
+        Assert.Equal("nopqrstuvwxyzabcdefghijklm", StringUtils.ConvertRot13("abcdefghijklmnopqrstuvwxyz"))
+        
+    [<Fact>]
+    let ``converts uppercase letters correctly`` () =
+        Assert.Equal("NOPQRSTUVWXYZABCDEFGHIJKLM", StringUtils.ConvertRot13("ABCDEFGHIJKLMNOPQRSTUVWXYZ"))
+        
+    [<Fact>]
+    let ``converts mixed character types correctly`` () =
+        Assert.Equal("Uryyb, jbeyq! :)", StringUtils.ConvertRot13("Hello, world! :)"))
+
+
+module CountOccurrences =
+    open System
+
+    [<Fact>]
+    let ``empty input string returns zero`` () =
+        Assert.Equal(0, StringUtils.CountOccurrences("", "a"))
+
+    [<Fact>]
+    let ``empty searched string throws`` () =
+        Assert.Throws<ArgumentOutOfRangeException>(fun () -> StringUtils.CountOccurrences("hello", "") |> ignore)
+
+    [<Fact>]
+    let ``counts single letter characters correctly`` () =
+        Assert.Equal(3, StringUtils.CountOccurrences("hello world", "l"))
+
+    [<Fact>]
+    let ``counts longer substrings correctly`` () =
+        Assert.Equal(2, StringUtils.CountOccurrences("hello and welcome in hell", "hell"))
+
+    [<Fact>]
+    let ``does not count overlapping substrings`` () =
+        Assert.Equal(2, StringUtils.CountOccurrences("aaaaa", "aa"))

lib/TweetTest.Unit/Core/TestTwitterUtils.fs

@@ -97,4 +97,16 @@ module GetMediaLink_Orig =
         Assert.Equal(domain+"/profile_images/123.jpg:orig", getMediaLinkOrig(domain+"/profile_images/123.jpg:small"))
 
 
-// TODO add new tests
+module GetImageFileName =
+
+    [<Fact>]
+    let ``extracts file name from URL w/o quality suffix`` () =
+        Assert.Equal("test.jpg", TwitterUtils.GetImageFileName("http://example.com/test.jpg"))
+        
+    [<Fact>]
+    let ``extracts file name from URL with quality suffix`` () =
+        Assert.Equal("test.jpg", TwitterUtils.GetImageFileName("http://example.com/test.jpg:orig"))
+
+    [<Fact>]
+    let ``extracts file name from URL with a port`` () =
+        Assert.Equal("test.jpg", TwitterUtils.GetImageFileName("http://example.com:80/test.jpg"))

lib/TweetTest.Unit/Data/TestResult.fs

@@ -0,0 +1,57 @@
+namespace Unit.Data
+
+open Xunit
+open TweetDuck.Data
+open System
+
+
+module TestResult_WithValue =
+    let result = Result<int>(10)
+
+    [<Fact>]
+    let ``HasValue returns true`` () =
+        Assert.True(result.HasValue)
+
+    [<Fact>]
+    let ``Accessing Value returns the provided value`` () =
+        Assert.Equal(10, result.Value)
+
+    [<Fact>]
+    let ``Accessing Exception throws`` () =
+        Assert.Throws<InvalidOperationException>(fun () -> result.Exception |> ignore)
+
+    [<Fact>]
+    let ``Handle calls the correct callback`` () =
+        let passTest = fun _ -> ()
+        let failTest = fun _ -> Assert.True(false)
+        result.Handle(Action<_>(passTest), Action<_>(failTest))
+
+    [<Fact>]
+    let ``Select returns another valid Result`` () =
+        Assert.Equal(20, result.Select(fun x -> x * 2).Value)
+
+
+module TestResult_WithException =
+    let result = Result<int>(IndexOutOfRangeException("bad"))
+
+    [<Fact>]
+    let ``HasValue returns false`` () =
+        Assert.False(result.HasValue)
+
+    [<Fact>]
+    let ``Accessing Value throws`` () =
+        Assert.Throws<InvalidOperationException>(fun () -> result.Value |> ignore)
+
+    [<Fact>]
+    let ``Accessing Exception returns the provided exception`` () =
+        Assert.IsType<IndexOutOfRangeException>(result.Exception)
+
+    [<Fact>]
+    let ``Handle calls the correct callback`` () =
+        let passTest = fun _ -> ()
+        let failTest = fun _ -> Assert.True(false)
+        result.Handle(Action<_>(failTest), Action<_>(passTest))
+
+    [<Fact>]
+    let ``Select returns a Result with the same Exception`` () =
+        Assert.Same(result.Exception, result.Select(fun x -> x * 2).Exception)

lib/TweetTest.Unit/TweetTest.Unit.fsproj

@@ -62,9 +62,10 @@
   <Import Project="..\..\packages\Microsoft.NET.Test.Sdk.15.7.2\build\net45\Microsoft.Net.Test.Sdk.targets" Condition="Exists('..\..\packages\Microsoft.NET.Test.Sdk.15.7.2\build\net45\Microsoft.Net.Test.Sdk.targets')" />
   <ItemGroup>
     <Content Include="packages.config" />
-    <Compile Include="Core\TestStringUtils.fs" />
     <Compile Include="Core\TestBrowserUtils.fs" />
+    <Compile Include="Core\TestStringUtils.fs" />
     <Compile Include="Core\TestTwitterUtils.fs" />
+    <Compile Include="Data\TestResult.fs" />
   </ItemGroup>
   <ItemGroup>
     <Reference Include="Microsoft.VisualStudio.CodeCoverage.Shim">