diff --git a/ThScoreFileConverter.Core.Tests/Extensions/EnumExtensionsTests.cs b/ThScoreFileConverter.Core.Tests/Extensions/EnumExtensionsTests.cs
index 931e74fe..0094cf80 100644
--- a/ThScoreFileConverter.Core.Tests/Extensions/EnumExtensionsTests.cs
+++ b/ThScoreFileConverter.Core.Tests/Extensions/EnumExtensionsTests.cs
@@ -3,7 +3,6 @@
 using System.Globalization;
 using ThScoreFileConverter.Core.Extensions;
 using ThScoreFileConverter.Core.Models;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 
 namespace ThScoreFileConverter.Core.Tests.Extensions;
 
diff --git a/ThScoreFileConverter.Core.Tests/Extensions/EnumerableExtensionsTests.cs b/ThScoreFileConverter.Core.Tests/Extensions/EnumerableExtensionsTests.cs
index eff902bb..d4589d6a 100644
--- a/ThScoreFileConverter.Core.Tests/Extensions/EnumerableExtensionsTests.cs
+++ b/ThScoreFileConverter.Core.Tests/Extensions/EnumerableExtensionsTests.cs
@@ -1,6 +1,5 @@
 using System;
 using ThScoreFileConverter.Core.Extensions;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 
 namespace ThScoreFileConverter.Core.Tests.Extensions;
 
diff --git a/ThScoreFileConverter.Core.Tests/Helpers/EnumHelperTests.cs b/ThScoreFileConverter.Core.Tests/Helpers/EnumHelperTests.cs
index df487f1e..54c67c31 100644
--- a/ThScoreFileConverter.Core.Tests/Helpers/EnumHelperTests.cs
+++ b/ThScoreFileConverter.Core.Tests/Helpers/EnumHelperTests.cs
@@ -1,6 +1,5 @@
 using System;
 using ThScoreFileConverter.Core.Helpers;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using Protagonist = ThScoreFileConverter.Core.Tests.Extensions.Protagonist;
 using UnnamedCharacter = ThScoreFileConverter.Core.Tests.Extensions.UnnamedCharacter;
 
diff --git a/ThScoreFileConverter.Core.Tests/Models/CharacterAttributeTests.cs b/ThScoreFileConverter.Core.Tests/Models/CharacterAttributeTests.cs
index 040b5a92..02e937e1 100644
--- a/ThScoreFileConverter.Core.Tests/Models/CharacterAttributeTests.cs
+++ b/ThScoreFileConverter.Core.Tests/Models/CharacterAttributeTests.cs
@@ -2,7 +2,6 @@
 using System.Globalization;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Resources;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 
 namespace ThScoreFileConverter.Core.Tests.Models;
 
diff --git a/ThScoreFileConverter.Core.Tests/Models/DefinitionsTests.cs b/ThScoreFileConverter.Core.Tests/Models/DefinitionsTests.cs
index 7f1db648..5d46614a 100644
--- a/ThScoreFileConverter.Core.Tests/Models/DefinitionsTests.cs
+++ b/ThScoreFileConverter.Core.Tests/Models/DefinitionsTests.cs
@@ -1,6 +1,5 @@
 using System.Collections.Generic;
 using ThScoreFileConverter.Core.Models;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 
 namespace ThScoreFileConverter.Core.Tests.Models;
 
diff --git a/ThScoreFileConverter.Core.Tests/Models/SpellCardInfoTests.cs b/ThScoreFileConverter.Core.Tests/Models/SpellCardInfoTests.cs
index 51b4eb30..972708bd 100644
--- a/ThScoreFileConverter.Core.Tests/Models/SpellCardInfoTests.cs
+++ b/ThScoreFileConverter.Core.Tests/Models/SpellCardInfoTests.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using ThScoreFileConverter.Core.Models;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using CardInfo = ThScoreFileConverter.Core.Models.SpellCardInfo<
     ThScoreFileConverter.Core.Models.Stage, ThScoreFileConverter.Core.Models.Level>;
 
diff --git a/ThScoreFileConverter.Core.Tests/Models/Th07/DefinitionsTests.cs b/ThScoreFileConverter.Core.Tests/Models/Th07/DefinitionsTests.cs
index d7bc418d..3dc3f04b 100644
--- a/ThScoreFileConverter.Core.Tests/Models/Th07/DefinitionsTests.cs
+++ b/ThScoreFileConverter.Core.Tests/Models/Th07/DefinitionsTests.cs
@@ -1,6 +1,5 @@
 using System.Collections.Generic;
 using ThScoreFileConverter.Core.Models.Th07;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 
 namespace ThScoreFileConverter.Core.Tests.Models.Th07;
 
diff --git a/ThScoreFileConverter.Core.Tests/Models/Th08/DefinitionsTests.cs b/ThScoreFileConverter.Core.Tests/Models/Th08/DefinitionsTests.cs
index 3797d05e..b65f8a4c 100644
--- a/ThScoreFileConverter.Core.Tests/Models/Th08/DefinitionsTests.cs
+++ b/ThScoreFileConverter.Core.Tests/Models/Th08/DefinitionsTests.cs
@@ -1,6 +1,5 @@
 using System.Collections.Generic;
 using ThScoreFileConverter.Core.Models.Th08;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 
 namespace ThScoreFileConverter.Core.Tests.Models.Th08;
 
diff --git a/ThScoreFileConverter.Core.Tests/Models/Th123/DefinitionsTests.cs b/ThScoreFileConverter.Core.Tests/Models/Th123/DefinitionsTests.cs
index 41d07aa4..db5c6168 100644
--- a/ThScoreFileConverter.Core.Tests/Models/Th123/DefinitionsTests.cs
+++ b/ThScoreFileConverter.Core.Tests/Models/Th123/DefinitionsTests.cs
@@ -1,6 +1,5 @@
 using System.Collections.Generic;
 using ThScoreFileConverter.Core.Models.Th123;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 
 namespace ThScoreFileConverter.Core.Tests.Models.Th123;
 
diff --git a/ThScoreFileConverter.Core.Tests/Usings.cs b/ThScoreFileConverter.Core.Tests/Usings.cs
index ab67c7ea..10aae16d 100644
--- a/ThScoreFileConverter.Core.Tests/Usings.cs
+++ b/ThScoreFileConverter.Core.Tests/Usings.cs
@@ -1 +1,2 @@
-global using Microsoft.VisualStudio.TestTools.UnitTesting;
\ No newline at end of file
+global using Microsoft.VisualStudio.TestTools.UnitTesting;
+global using ThScoreFileConverter.Core.Tests.UnitTesting;
diff --git a/ThScoreFileConverter.Tests/Extensions/BinaryReaderExtensionsTests.cs b/ThScoreFileConverter.Tests/Extensions/BinaryReaderExtensionsTests.cs
index 83017003..22872524 100644
--- a/ThScoreFileConverter.Tests/Extensions/BinaryReaderExtensionsTests.cs
+++ b/ThScoreFileConverter.Tests/Extensions/BinaryReaderExtensionsTests.cs
@@ -3,7 +3,6 @@
 using System.IO;
 using System.Linq;
 using System.Text;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Extensions;
 using ThScoreFileConverter.Helpers;
 
diff --git a/ThScoreFileConverter.Tests/Interactivity/OpenFileDialogActionResultTests.cs b/ThScoreFileConverter.Tests/Interactivity/OpenFileDialogActionResultTests.cs
index 0e978c28..30a74a23 100644
--- a/ThScoreFileConverter.Tests/Interactivity/OpenFileDialogActionResultTests.cs
+++ b/ThScoreFileConverter.Tests/Interactivity/OpenFileDialogActionResultTests.cs
@@ -1,5 +1,4 @@
 using System;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Interactivity;
 
 namespace ThScoreFileConverter.Tests.Interactivity;
diff --git a/ThScoreFileConverter.Tests/Models/ReadOnlyCP932BytesTests.cs b/ThScoreFileConverter.Tests/Models/ReadOnlyCP932BytesTests.cs
index c5702c04..ffb8b9bd 100644
--- a/ThScoreFileConverter.Tests/Models/ReadOnlyCP932BytesTests.cs
+++ b/ThScoreFileConverter.Tests/Models/ReadOnlyCP932BytesTests.cs
@@ -1,6 +1,5 @@
 using System.Collections;
 using System.Linq;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th06/CardAttackTests.cs b/ThScoreFileConverter.Tests/Models/Th06/CardAttackTests.cs
index d64471d3..e3ac46ec 100644
--- a/ThScoreFileConverter.Tests/Models/Th06/CardAttackTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th06/CardAttackTests.cs
@@ -1,6 +1,5 @@
 using System.IO;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th06;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th06/ChapterTests.cs b/ThScoreFileConverter.Tests/Models/Th06/ChapterTests.cs
index b02ada7e..628b96ea 100644
--- a/ThScoreFileConverter.Tests/Models/Th06/ChapterTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th06/ChapterTests.cs
@@ -1,7 +1,6 @@
 using System;
 using System.IO;
 using System.Linq;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th06;
 using ThScoreFileConverter.Tests.Models.Th06.Wrappers;
 using ThScoreFileConverter.Tests.UnitTesting;
diff --git a/ThScoreFileConverter.Tests/Models/Th06/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th06/ClearDataTests.cs
index fb1b1a33..b2baefd8 100644
--- a/ThScoreFileConverter.Tests/Models/Th06/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th06/ClearDataTests.cs
@@ -6,7 +6,6 @@
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th06;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th06;
 using ThScoreFileConverter.Tests.UnitTesting;
 using IClearData = ThScoreFileConverter.Models.Th06.IClearData<
diff --git a/ThScoreFileConverter.Tests/Models/Th06/HighScoreTests.cs b/ThScoreFileConverter.Tests/Models/Th06/HighScoreTests.cs
index 4077c113..66bbcad9 100644
--- a/ThScoreFileConverter.Tests/Models/Th06/HighScoreTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th06/HighScoreTests.cs
@@ -4,7 +4,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th06;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th06;
 using ThScoreFileConverter.Tests.UnitTesting;
 using IHighScore = ThScoreFileConverter.Models.Th06.IHighScore<
diff --git a/ThScoreFileConverter.Tests/Models/Th07/CardAttackTests.cs b/ThScoreFileConverter.Tests/Models/Th07/CardAttackTests.cs
index 1ea9ce62..98138557 100644
--- a/ThScoreFileConverter.Tests/Models/Th07/CardAttackTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th07/CardAttackTests.cs
@@ -3,7 +3,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th07;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th07;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th06.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th07/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th07/ClearDataTests.cs
index ca7a8210..af3d8730 100644
--- a/ThScoreFileConverter.Tests/Models/Th07/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th07/ClearDataTests.cs
@@ -5,7 +5,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th07;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th07;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th06.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th07/HighScoreTests.cs b/ThScoreFileConverter.Tests/Models/Th07/HighScoreTests.cs
index 50d6fa5a..75e31e4f 100644
--- a/ThScoreFileConverter.Tests/Models/Th07/HighScoreTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th07/HighScoreTests.cs
@@ -3,7 +3,6 @@
 using System.IO;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models.Th07;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th07;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th06.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th07/LastNameTests.cs b/ThScoreFileConverter.Tests/Models/Th07/LastNameTests.cs
index 46f64742..0c53a270 100644
--- a/ThScoreFileConverter.Tests/Models/Th07/LastNameTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th07/LastNameTests.cs
@@ -1,5 +1,4 @@
 using System.IO;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th07;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th06.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th07/PlayCountTests.cs b/ThScoreFileConverter.Tests/Models/Th07/PlayCountTests.cs
index 4b9a24be..42edf5a6 100644
--- a/ThScoreFileConverter.Tests/Models/Th07/PlayCountTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th07/PlayCountTests.cs
@@ -3,7 +3,6 @@
 using System.Linq;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th07;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th07;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th07/VersionInfoTests.cs b/ThScoreFileConverter.Tests/Models/Th07/VersionInfoTests.cs
index 83b6910d..343b0d03 100644
--- a/ThScoreFileConverter.Tests/Models/Th07/VersionInfoTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th07/VersionInfoTests.cs
@@ -1,5 +1,4 @@
 using System.IO;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th07;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th06.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th075/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th075/ClearDataTests.cs
index cbcd4f6e..24ded167 100644
--- a/ThScoreFileConverter.Tests/Models/Th075/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th075/ClearDataTests.cs
@@ -1,6 +1,5 @@
 using System.Linq;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Helpers;
 using ThScoreFileConverter.Models.Th075;
 using ThScoreFileConverter.Tests.Models.Th075.Stubs;
diff --git a/ThScoreFileConverter.Tests/Models/Th075/StatusTests.cs b/ThScoreFileConverter.Tests/Models/Th075/StatusTests.cs
index d8830871..5bd5f6a5 100644
--- a/ThScoreFileConverter.Tests/Models/Th075/StatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th075/StatusTests.cs
@@ -3,7 +3,6 @@
 using System.Linq;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th075;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th075;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th08/CardAttackCareerTests.cs b/ThScoreFileConverter.Tests/Models/Th08/CardAttackCareerTests.cs
index dedb98f2..ba1ec33c 100644
--- a/ThScoreFileConverter.Tests/Models/Th08/CardAttackCareerTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th08/CardAttackCareerTests.cs
@@ -4,7 +4,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th08;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th08;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th08/CardAttackTests.cs b/ThScoreFileConverter.Tests/Models/Th08/CardAttackTests.cs
index 506dbce5..2d4298b4 100644
--- a/ThScoreFileConverter.Tests/Models/Th08/CardAttackTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th08/CardAttackTests.cs
@@ -4,7 +4,6 @@
 using System.Linq;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models.Th08;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th08;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th06.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th08/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th08/ClearDataTests.cs
index 267e757d..badeee23 100644
--- a/ThScoreFileConverter.Tests/Models/Th08/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th08/ClearDataTests.cs
@@ -6,7 +6,6 @@
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th08;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th08;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th06.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th08/HighScoreTests.cs b/ThScoreFileConverter.Tests/Models/Th08/HighScoreTests.cs
index 77ed217f..44c5f800 100644
--- a/ThScoreFileConverter.Tests/Models/Th08/HighScoreTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th08/HighScoreTests.cs
@@ -5,7 +5,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th08;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th08;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th06.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th08/PlayCountTests.cs b/ThScoreFileConverter.Tests/Models/Th08/PlayCountTests.cs
index e62a0bae..352f07a4 100644
--- a/ThScoreFileConverter.Tests/Models/Th08/PlayCountTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th08/PlayCountTests.cs
@@ -4,7 +4,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th08;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th08;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th08/PlayStatusTests.cs b/ThScoreFileConverter.Tests/Models/Th08/PlayStatusTests.cs
index b8a92349..ce1d6287 100644
--- a/ThScoreFileConverter.Tests/Models/Th08/PlayStatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th08/PlayStatusTests.cs
@@ -3,7 +3,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models;
 using ThScoreFileConverter.Models.Th08;
 using ThScoreFileConverter.Tests.UnitTesting;
diff --git a/ThScoreFileConverter.Tests/Models/Th08/PracticeScoreTests.cs b/ThScoreFileConverter.Tests/Models/Th08/PracticeScoreTests.cs
index 05316cbb..3262213a 100644
--- a/ThScoreFileConverter.Tests/Models/Th08/PracticeScoreTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th08/PracticeScoreTests.cs
@@ -6,7 +6,6 @@
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th08;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th08;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th06.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th09/ClearCountTests.cs b/ThScoreFileConverter.Tests/Models/Th09/ClearCountTests.cs
index 84909fb1..343d2c5f 100644
--- a/ThScoreFileConverter.Tests/Models/Th09/ClearCountTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th09/ClearCountTests.cs
@@ -4,7 +4,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th09;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th09/HighScoreTests.cs b/ThScoreFileConverter.Tests/Models/Th09/HighScoreTests.cs
index b1240719..649e6128 100644
--- a/ThScoreFileConverter.Tests/Models/Th09/HighScoreTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th09/HighScoreTests.cs
@@ -4,7 +4,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th09;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th09;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th06.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th09/PlayStatusTests.cs b/ThScoreFileConverter.Tests/Models/Th09/PlayStatusTests.cs
index 912779ab..e73748a2 100644
--- a/ThScoreFileConverter.Tests/Models/Th09/PlayStatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th09/PlayStatusTests.cs
@@ -3,7 +3,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th09;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models;
 using ThScoreFileConverter.Models.Th09;
 using ThScoreFileConverter.Tests.UnitTesting;
diff --git a/ThScoreFileConverter.Tests/Models/Th095/BestShotHeaderTests.cs b/ThScoreFileConverter.Tests/Models/Th095/BestShotHeaderTests.cs
index 6b4f71ef..9ac16cdf 100644
--- a/ThScoreFileConverter.Tests/Models/Th095/BestShotHeaderTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th095/BestShotHeaderTests.cs
@@ -5,7 +5,6 @@
 using CommunityToolkit.Diagnostics;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models.Th095;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th095;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th095/CardReplacerTests.cs b/ThScoreFileConverter.Tests/Models/Th095/CardReplacerTests.cs
index a43ceb60..5e11aac4 100644
--- a/ThScoreFileConverter.Tests/Models/Th095/CardReplacerTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th095/CardReplacerTests.cs
@@ -1,7 +1,6 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Globalization;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th095;
 
 namespace ThScoreFileConverter.Tests.Models.Th095;
diff --git a/ThScoreFileConverter.Tests/Models/Th095/ChapterTests.cs b/ThScoreFileConverter.Tests/Models/Th095/ChapterTests.cs
index c9d81427..5e31598e 100644
--- a/ThScoreFileConverter.Tests/Models/Th095/ChapterTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th095/ChapterTests.cs
@@ -1,7 +1,6 @@
 using System;
 using System.IO;
 using System.Linq;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th095;
 using ThScoreFileConverter.Tests.Models.Th095.Wrappers;
 using ThScoreFileConverter.Tests.UnitTesting;
diff --git a/ThScoreFileConverter.Tests/Models/Th095/StatusTests.cs b/ThScoreFileConverter.Tests/Models/Th095/StatusTests.cs
index 195fe1a2..c114ddee 100644
--- a/ThScoreFileConverter.Tests/Models/Th095/StatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th095/StatusTests.cs
@@ -1,6 +1,5 @@
 using System.IO;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th095;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th10/ChapterTests.cs b/ThScoreFileConverter.Tests/Models/Th10/ChapterTests.cs
index c8f3859d..d907f7dc 100644
--- a/ThScoreFileConverter.Tests/Models/Th10/ChapterTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th10/ChapterTests.cs
@@ -1,7 +1,6 @@
 using System;
 using System.IO;
 using System.Linq;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th10;
 using ThScoreFileConverter.Tests.Models.Th10.Wrappers;
 using ThScoreFileConverter.Tests.UnitTesting;
diff --git a/ThScoreFileConverter.Tests/Models/Th10/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th10/ClearDataTests.cs
index 6af85fe0..3e59d2dc 100644
--- a/ThScoreFileConverter.Tests/Models/Th10/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th10/ClearDataTests.cs
@@ -7,7 +7,6 @@
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th10;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th10;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th10/ScoreDataTests.cs b/ThScoreFileConverter.Tests/Models/Th10/ScoreDataTests.cs
index 9718a3c2..6b45c43d 100644
--- a/ThScoreFileConverter.Tests/Models/Th10/ScoreDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th10/ScoreDataTests.cs
@@ -3,7 +3,6 @@
 using System.IO;
 using System.Linq;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models;
 using ThScoreFileConverter.Models.Th10;
 using ThScoreFileConverter.Tests.UnitTesting;
diff --git a/ThScoreFileConverter.Tests/Models/Th10/SpellCardTests.cs b/ThScoreFileConverter.Tests/Models/Th10/SpellCardTests.cs
index 857c75e5..c8bc4c6a 100644
--- a/ThScoreFileConverter.Tests/Models/Th10/SpellCardTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th10/SpellCardTests.cs
@@ -4,7 +4,6 @@
 using System.Linq;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th10;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th10/StatusTests.cs b/ThScoreFileConverter.Tests/Models/Th10/StatusTests.cs
index f7572b95..874c0849 100644
--- a/ThScoreFileConverter.Tests/Models/Th10/StatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th10/StatusTests.cs
@@ -1,7 +1,6 @@
 using System.IO;
 using System.Linq;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th10;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th105/AllScoreDataTests.cs b/ThScoreFileConverter.Tests/Models/Th105/AllScoreDataTests.cs
index 0868a8c8..ba77ea49 100644
--- a/ThScoreFileConverter.Tests/Models/Th105/AllScoreDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th105/AllScoreDataTests.cs
@@ -2,7 +2,6 @@
 using System.Linq;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th105;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th105;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th105/StageInfoTests.cs b/ThScoreFileConverter.Tests/Models/Th105/StageInfoTests.cs
index 5e50b6db..fd356848 100644
--- a/ThScoreFileConverter.Tests/Models/Th105/StageInfoTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th105/StageInfoTests.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using ThScoreFileConverter.Core.Models.Th105;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Tests.UnitTesting;
 
 namespace ThScoreFileConverter.Tests.Models.Th105;
diff --git a/ThScoreFileConverter.Tests/Models/Th123/AllScoreDataTests.cs b/ThScoreFileConverter.Tests/Models/Th123/AllScoreDataTests.cs
index 1567a598..1f055f40 100644
--- a/ThScoreFileConverter.Tests/Models/Th123/AllScoreDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th123/AllScoreDataTests.cs
@@ -2,7 +2,6 @@
 using System.Linq;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th123;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th123;
 using ThScoreFileConverter.Tests.UnitTesting;
 using ICardForDeck = ThScoreFileConverter.Models.Th105.ICardForDeck;
diff --git a/ThScoreFileConverter.Tests/Models/Th125/BestShotHeaderTests.cs b/ThScoreFileConverter.Tests/Models/Th125/BestShotHeaderTests.cs
index 216cbe72..b08c6f62 100644
--- a/ThScoreFileConverter.Tests/Models/Th125/BestShotHeaderTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th125/BestShotHeaderTests.cs
@@ -5,7 +5,6 @@
 using CommunityToolkit.Diagnostics;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models.Th125;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th125;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th125/CardReplacerTests.cs b/ThScoreFileConverter.Tests/Models/Th125/CardReplacerTests.cs
index 5660f565..3c8ca554 100644
--- a/ThScoreFileConverter.Tests/Models/Th125/CardReplacerTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th125/CardReplacerTests.cs
@@ -1,7 +1,6 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Globalization;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th125;
 
 namespace ThScoreFileConverter.Tests.Models.Th125;
diff --git a/ThScoreFileConverter.Tests/Models/Th125/StatusTests.cs b/ThScoreFileConverter.Tests/Models/Th125/StatusTests.cs
index ae61dacc..4e344b67 100644
--- a/ThScoreFileConverter.Tests/Models/Th125/StatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th125/StatusTests.cs
@@ -1,6 +1,5 @@
 using System.IO;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th125;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th095.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th128/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th128/ClearDataTests.cs
index 43f37541..1add547b 100644
--- a/ThScoreFileConverter.Tests/Models/Th128/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th128/ClearDataTests.cs
@@ -5,7 +5,6 @@
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th128;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th128;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th128/SpellCardTests.cs b/ThScoreFileConverter.Tests/Models/Th128/SpellCardTests.cs
index 73640f94..ef2ccdee 100644
--- a/ThScoreFileConverter.Tests/Models/Th128/SpellCardTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th128/SpellCardTests.cs
@@ -4,7 +4,6 @@
 using System.Linq;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th128;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th128/StatusTests.cs b/ThScoreFileConverter.Tests/Models/Th128/StatusTests.cs
index 77780f06..793009b2 100644
--- a/ThScoreFileConverter.Tests/Models/Th128/StatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th128/StatusTests.cs
@@ -1,7 +1,6 @@
 using System.IO;
 using System.Linq;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th128;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th13/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th13/ClearDataTests.cs
index d817f802..36b58ad9 100644
--- a/ThScoreFileConverter.Tests/Models/Th13/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th13/ClearDataTests.cs
@@ -4,7 +4,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th13;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th13;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th13/SpellCardTests.cs b/ThScoreFileConverter.Tests/Models/Th13/SpellCardTests.cs
index 69ec80b4..628b5736 100644
--- a/ThScoreFileConverter.Tests/Models/Th13/SpellCardTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th13/SpellCardTests.cs
@@ -4,7 +4,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th13;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th13;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th13/StatusTests.cs b/ThScoreFileConverter.Tests/Models/Th13/StatusTests.cs
index e0ee7eaf..6bbd4741 100644
--- a/ThScoreFileConverter.Tests/Models/Th13/StatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th13/StatusTests.cs
@@ -1,7 +1,6 @@
 using System.IO;
 using System.Linq;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th13;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th135/AllScoreDataTests.cs b/ThScoreFileConverter.Tests/Models/Th135/AllScoreDataTests.cs
index e5e9284a..3c8534ca 100644
--- a/ThScoreFileConverter.Tests/Models/Th135/AllScoreDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th135/AllScoreDataTests.cs
@@ -3,7 +3,6 @@
 using System.Linq;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th135;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th135;
 using ThScoreFileConverter.Tests.UnitTesting;
 using SQOT = ThScoreFileConverter.Squirrel.SQObjectType;
diff --git a/ThScoreFileConverter.Tests/Models/Th14/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th14/ClearDataTests.cs
index f0b0b773..d6048615 100644
--- a/ThScoreFileConverter.Tests/Models/Th14/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th14/ClearDataTests.cs
@@ -5,7 +5,6 @@
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th14;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th14;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th143/CardReplacerTests.cs b/ThScoreFileConverter.Tests/Models/Th143/CardReplacerTests.cs
index 303fe584..cfa8e2ea 100644
--- a/ThScoreFileConverter.Tests/Models/Th143/CardReplacerTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th143/CardReplacerTests.cs
@@ -3,7 +3,6 @@
 using System.Globalization;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models.Th143;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th143;
 
 namespace ThScoreFileConverter.Tests.Models.Th143;
diff --git a/ThScoreFileConverter.Tests/Models/Th143/ScoreTests.cs b/ThScoreFileConverter.Tests/Models/Th143/ScoreTests.cs
index 7b00c5c7..02d0f879 100644
--- a/ThScoreFileConverter.Tests/Models/Th143/ScoreTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th143/ScoreTests.cs
@@ -3,7 +3,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th143;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th143;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th143/StatusTests.cs b/ThScoreFileConverter.Tests/Models/Th143/StatusTests.cs
index 5165bb36..112aca41 100644
--- a/ThScoreFileConverter.Tests/Models/Th143/StatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th143/StatusTests.cs
@@ -4,7 +4,6 @@
 using System.Linq;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models.Th143;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th143;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th145/AllScoreDataTests.cs b/ThScoreFileConverter.Tests/Models/Th145/AllScoreDataTests.cs
index b742b585..f677c4a5 100644
--- a/ThScoreFileConverter.Tests/Models/Th145/AllScoreDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th145/AllScoreDataTests.cs
@@ -3,7 +3,6 @@
 using System.Linq;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th145;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th145;
 using ThScoreFileConverter.Tests.UnitTesting;
 using SQOT = ThScoreFileConverter.Squirrel.SQObjectType;
diff --git a/ThScoreFileConverter.Tests/Models/Th15/ClearDataPerGameModeTests.cs b/ThScoreFileConverter.Tests/Models/Th15/ClearDataPerGameModeTests.cs
index 8df648d2..9f78c55b 100644
--- a/ThScoreFileConverter.Tests/Models/Th15/ClearDataPerGameModeTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th15/ClearDataPerGameModeTests.cs
@@ -5,7 +5,6 @@
 using NSubstitute;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th13;
 using ThScoreFileConverter.Models.Th15;
 using ThScoreFileConverter.Tests.UnitTesting;
diff --git a/ThScoreFileConverter.Tests/Models/Th15/ScoreDataTests.cs b/ThScoreFileConverter.Tests/Models/Th15/ScoreDataTests.cs
index 0e0a61dd..849b4b5e 100644
--- a/ThScoreFileConverter.Tests/Models/Th15/ScoreDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th15/ScoreDataTests.cs
@@ -3,7 +3,6 @@
 using System.IO;
 using System.Linq;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th15;
 using ThScoreFileConverter.Tests.UnitTesting;
 using StageProgress = ThScoreFileConverter.Models.Th13.StageProgress;
diff --git a/ThScoreFileConverter.Tests/Models/Th15/SpellCardTests.cs b/ThScoreFileConverter.Tests/Models/Th15/SpellCardTests.cs
index 3dbaeb7a..f8240843 100644
--- a/ThScoreFileConverter.Tests/Models/Th15/SpellCardTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th15/SpellCardTests.cs
@@ -3,7 +3,6 @@
 using System.Linq;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th15;
 using ThScoreFileConverter.Tests.UnitTesting;
 using ISpellCard = ThScoreFileConverter.Models.Th13.ISpellCard<ThScoreFileConverter.Core.Models.Level>;
diff --git a/ThScoreFileConverter.Tests/Models/Th155/AllScoreDataTests.cs b/ThScoreFileConverter.Tests/Models/Th155/AllScoreDataTests.cs
index 89d986fb..2347b4f4 100644
--- a/ThScoreFileConverter.Tests/Models/Th155/AllScoreDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th155/AllScoreDataTests.cs
@@ -3,7 +3,6 @@
 using System.Linq;
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models.Th155;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th155;
 using ThScoreFileConverter.Tests.UnitTesting;
 using SQOT = ThScoreFileConverter.Squirrel.SQObjectType;
diff --git a/ThScoreFileConverter.Tests/Models/Th16/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th16/ClearDataTests.cs
index 46199e44..333b3786 100644
--- a/ThScoreFileConverter.Tests/Models/Th16/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th16/ClearDataTests.cs
@@ -5,7 +5,6 @@
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th16;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th16;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th16/ScoreDataTests.cs b/ThScoreFileConverter.Tests/Models/Th16/ScoreDataTests.cs
index 9c740467..45df5b6b 100644
--- a/ThScoreFileConverter.Tests/Models/Th16/ScoreDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th16/ScoreDataTests.cs
@@ -3,7 +3,6 @@
 using System.IO;
 using System.Linq;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th16;
 using ThScoreFileConverter.Tests.UnitTesting;
 using StageProgress = ThScoreFileConverter.Models.Th13.StageProgress;
diff --git a/ThScoreFileConverter.Tests/Models/Th165/BestShotHeaderTests.cs b/ThScoreFileConverter.Tests/Models/Th165/BestShotHeaderTests.cs
index 2ab3b628..a3dc1c79 100644
--- a/ThScoreFileConverter.Tests/Models/Th165/BestShotHeaderTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th165/BestShotHeaderTests.cs
@@ -4,7 +4,6 @@
 using CommunityToolkit.Diagnostics;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models.Th165;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th165;
 using ThScoreFileConverter.Tests.UnitTesting;
 
diff --git a/ThScoreFileConverter.Tests/Models/Th165/CardReplacerTests.cs b/ThScoreFileConverter.Tests/Models/Th165/CardReplacerTests.cs
index a15524d9..18142279 100644
--- a/ThScoreFileConverter.Tests/Models/Th165/CardReplacerTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th165/CardReplacerTests.cs
@@ -2,7 +2,6 @@
 using System.Collections.Immutable;
 using System.Globalization;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th165;
 
 namespace ThScoreFileConverter.Tests.Models.Th165;
diff --git a/ThScoreFileConverter.Tests/Models/Th165/StatusTests.cs b/ThScoreFileConverter.Tests/Models/Th165/StatusTests.cs
index 46171d4e..378b526e 100644
--- a/ThScoreFileConverter.Tests/Models/Th165/StatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th165/StatusTests.cs
@@ -1,7 +1,6 @@
 using System.IO;
 using System.Linq;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th165;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th17/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th17/ClearDataTests.cs
index 5a47fcbd..799b46c3 100644
--- a/ThScoreFileConverter.Tests/Models/Th17/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th17/ClearDataTests.cs
@@ -5,7 +5,6 @@
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th17;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th17;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th17/ScoreDataTests.cs b/ThScoreFileConverter.Tests/Models/Th17/ScoreDataTests.cs
index 488c9b66..2bc97cbb 100644
--- a/ThScoreFileConverter.Tests/Models/Th17/ScoreDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th17/ScoreDataTests.cs
@@ -3,7 +3,6 @@
 using System.IO;
 using System.Linq;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th17;
 using ThScoreFileConverter.Tests.UnitTesting;
 using IScoreData = ThScoreFileConverter.Models.Th10.IScoreData<ThScoreFileConverter.Models.Th13.StageProgress>;
diff --git a/ThScoreFileConverter.Tests/Models/Th17/StatusTests.cs b/ThScoreFileConverter.Tests/Models/Th17/StatusTests.cs
index d4fe48f6..2abd2ef8 100644
--- a/ThScoreFileConverter.Tests/Models/Th17/StatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th17/StatusTests.cs
@@ -1,6 +1,5 @@
 using System.IO;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th17;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th18/ClearDataTests.cs b/ThScoreFileConverter.Tests/Models/Th18/ClearDataTests.cs
index 1dcca0a9..9128f905 100644
--- a/ThScoreFileConverter.Tests/Models/Th18/ClearDataTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th18/ClearDataTests.cs
@@ -6,7 +6,6 @@
 using ThScoreFileConverter.Core.Helpers;
 using ThScoreFileConverter.Core.Models;
 using ThScoreFileConverter.Core.Models.Th18;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th18;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/Models/Th18/SpellCardTests.cs b/ThScoreFileConverter.Tests/Models/Th18/SpellCardTests.cs
index 923095b0..d4265e4a 100644
--- a/ThScoreFileConverter.Tests/Models/Th18/SpellCardTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th18/SpellCardTests.cs
@@ -3,7 +3,6 @@
 using System.Linq;
 using NSubstitute;
 using ThScoreFileConverter.Core.Models;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th18;
 using ThScoreFileConverter.Tests.UnitTesting;
 using ISpellCard = ThScoreFileConverter.Models.Th13.ISpellCard<ThScoreFileConverter.Core.Models.Level>;
diff --git a/ThScoreFileConverter.Tests/Models/Th18/StatusTests.cs b/ThScoreFileConverter.Tests/Models/Th18/StatusTests.cs
index 552da9c7..ea6dd07d 100644
--- a/ThScoreFileConverter.Tests/Models/Th18/StatusTests.cs
+++ b/ThScoreFileConverter.Tests/Models/Th18/StatusTests.cs
@@ -1,6 +1,5 @@
 using System.IO;
 using NSubstitute;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Models.Th18;
 using ThScoreFileConverter.Tests.UnitTesting;
 using Chapter = ThScoreFileConverter.Models.Th10.Chapter;
diff --git a/ThScoreFileConverter.Tests/SettingsTests.cs b/ThScoreFileConverter.Tests/SettingsTests.cs
index 25a7dbb8..d524abe9 100644
--- a/ThScoreFileConverter.Tests/SettingsTests.cs
+++ b/ThScoreFileConverter.Tests/SettingsTests.cs
@@ -3,7 +3,6 @@
 using System.Globalization;
 using System.IO;
 using System.Windows;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 
 namespace ThScoreFileConverter.Tests;
 
diff --git a/ThScoreFileConverter.Tests/UnitTesting/TestUtils.cs b/ThScoreFileConverter.Tests/UnitTesting/TestUtils.cs
index cdc056c9..081b3b15 100644
--- a/ThScoreFileConverter.Tests/UnitTesting/TestUtils.cs
+++ b/ThScoreFileConverter.Tests/UnitTesting/TestUtils.cs
@@ -113,7 +113,7 @@ public static TResult Cast<TResult>(object value)
     public static IEnumerable<object[]> GetInvalidEnumerators<TEnum>()
         where TEnum : struct, Enum
     {
-        return Core.Tests.UnitTesting.TestHelper.GetInvalidEnumerators<TEnum>();
+        return TestHelper.GetInvalidEnumerators<TEnum>();
     }
 
     private static bool Invoke<T>(Action<T> action, string key, T value)
diff --git a/ThScoreFileConverter.Tests/Usings.cs b/ThScoreFileConverter.Tests/Usings.cs
index ab67c7ea..10aae16d 100644
--- a/ThScoreFileConverter.Tests/Usings.cs
+++ b/ThScoreFileConverter.Tests/Usings.cs
@@ -1 +1,2 @@
-global using Microsoft.VisualStudio.TestTools.UnitTesting;
\ No newline at end of file
+global using Microsoft.VisualStudio.TestTools.UnitTesting;
+global using ThScoreFileConverter.Core.Tests.UnitTesting;
diff --git a/ThScoreFileConverter.Tests/ViewModels/MainWindowViewModelTests.cs b/ThScoreFileConverter.Tests/ViewModels/MainWindowViewModelTests.cs
index 7ce29fad..48c9fb80 100644
--- a/ThScoreFileConverter.Tests/ViewModels/MainWindowViewModelTests.cs
+++ b/ThScoreFileConverter.Tests/ViewModels/MainWindowViewModelTests.cs
@@ -8,7 +8,6 @@
 using NSubstitute;
 using Reactive.Bindings.Extensions;
 using ThScoreFileConverter.Adapters;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Interactivity;
 using ThScoreFileConverter.Models;
 using ThScoreFileConverter.Properties;
diff --git a/ThScoreFileConverter.Tests/ViewModels/SettingWindowViewModelTests.cs b/ThScoreFileConverter.Tests/ViewModels/SettingWindowViewModelTests.cs
index 117eb9b5..fd1724eb 100644
--- a/ThScoreFileConverter.Tests/ViewModels/SettingWindowViewModelTests.cs
+++ b/ThScoreFileConverter.Tests/ViewModels/SettingWindowViewModelTests.cs
@@ -5,7 +5,6 @@
 using NSubstitute;
 using Reactive.Bindings.Extensions;
 using ThScoreFileConverter.Adapters;
-using ThScoreFileConverter.Core.Tests.UnitTesting;
 using ThScoreFileConverter.Interactivity;
 using ThScoreFileConverter.Models;
 using ThScoreFileConverter.Properties;