Bump NUnit from 3.14.0 to 4.0.0 (#288)

* Bump NUnit from 3.14.0 to 4.0.0

Bumps [NUnit](https://github.com/nunit/nunit) from 3.14.0 to 4.0.0.
- [Release notes](https://github.com/nunit/nunit/releases)
- [Changelog](https://github.com/nunit/nunit/blob/master/CHANGES.md)
- [Commits](nunit/nunit@v3.14.0...v4.0.0)

---
updated-dependencies:
- dependency-name: NUnit
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

* Fix tests

Fix tests broken by NUnit 4 upgrade.

---------

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: martincostello <[email protected]>

Directory.Packages.props

@@ -4,7 +4,7 @@
     <PackageVersion Include="Humanizer" Version="2.14.1" />
     <PackageVersion Include="Karambolo.PO.Compact" Version="1.3.0" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-    <PackageVersion Include="NUnit" Version="3.14.0" />
+    <PackageVersion Include="NUnit" Version="4.0.0" />
     <PackageVersion Include="NUnit3TestAdapter" Version="4.5.0" />
   </ItemGroup>
 </Project>

PseudoLocalizer.Core.Tests/POProcessorTests.cs

@@ -2,6 +2,7 @@
 using System.IO;
 using System.Linq;
 using NUnit.Framework;
+using NUnit.Framework.Legacy;
 
 namespace PseudoLocalizer.Core.Tests
 {
@@ -28,6 +29,7 @@ public void ShouldLeaveTheFileUntouchedWhenUsingAnIdentityTransformation()
                 processor.Transform(inputStream, outputStream);
             }
 
+            Assert.That(OutputFileName, Does.Exist);
             FileAssert.AreEqual(Test1FileName, OutputFileName);
         }
 
@@ -42,6 +44,7 @@ public void ShouldReverseStringsButLeaveTheCommentsUntouchedWhenTransformingWith
                 processor.Transform(inputStream, outputStream);
             }
 
+            Assert.That(OutputFileName, Does.Exist);
             FileAssert.AreEqual("Mirror.po", OutputFileName);
         }
 
@@ -56,6 +59,7 @@ public void ShouldAddFunnyAccentsWhenTransformingWithTheAccenterTransformation()
                 processor.Transform(inputStream, outputStream);
             }
 
+            Assert.That(OutputFileName, Does.Exist);
             FileAssert.AreEqual("Accents.po", OutputFileName);
         }
 
@@ -72,6 +76,7 @@ public void ShouldApplyMultipleTransformations()
                 processor.Transform(inputStream, outputStream);
             }
 
+            Assert.That(OutputFileName, Does.Exist);
             FileAssert.AreEqual("Multiple.po", OutputFileName);
         }
 
@@ -88,8 +93,8 @@ public void ShouldThrowForBadInputFile()
                 ex = Assert.Throws<POFileFormatException>(() => processor.Transform(inputStream, outputStream));
             }
 
-            Assert.AreEqual("Entry beginning at 18,1 must not have an empty id." + Environment.NewLine, ex.Message);
-            Assert.AreEqual("Entry beginning at 18,1 must not have an empty id.", ex.DiagnosticMessages.First());
+            Assert.That(ex.Message, Is.EqualTo("Entry beginning at 18,1 must not have an empty id." + Environment.NewLine));
+            Assert.That(ex.DiagnosticMessages.First(), Is.EqualTo("Entry beginning at 18,1 must not have an empty id."));
         }
 
         private static void DeleteOutputFile()