check arguments

smdn · Dec 23, 2022 · 3cb8a17 · 3cb8a17
1 parent 6d131af
commit 3cb8a17
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diff --git a/src/Smdn.Text.Ondulish/Smdn.Text.Ondulish/KanaUtils.cs b/src/Smdn.Text.Ondulish/Smdn.Text.Ondulish/KanaUtils.cs
@@ -1,6 +1,7 @@
 // SPDX-FileCopyrightText: 2012 smdn <smdn@smdn.jp>
 // SPDX-License-Identifier: MIT
 
+using System;
 using System.Text;
 
 namespace Smdn.Text.Ondulish;
@@ -27,6 +28,11 @@ public static class KanaUtils {
 
   public static string ConvertWideHiraganaToKatakana(string input)
   {
+    if (input is null)
+      throw new ArgumentNullException(nameof(input));
+    if (input.Length == 0)
+      return string.Empty;
+
 #if SYSTEM_STRING_CREATE
     return string.Create(input.Length, input, (chars, s) => {
       for (var index = 0; index < chars.Length; index++) {
@@ -52,6 +58,11 @@ public static string ConvertWideHiraganaToKatakana(string input)
 
   public static string ConvertWideKatakanaToHiragana(string input)
   {
+    if (input is null)
+      throw new ArgumentNullException(nameof(input));
+    if (input.Length == 0)
+      return string.Empty;
+
 #if SYSTEM_STRING_CREATE
     return string.Create(input.Length, input, (chars, s) => {
       for (var index = 0; index < chars.Length; index++) {
@@ -77,6 +88,11 @@ public static string ConvertWideKatakanaToHiragana(string input)
 
   public static string ConvertWideKatakanaToNarrowKatakana(string input)
   {
+    if (input is null)
+      throw new ArgumentNullException(nameof(input));
+    if (input.Length == 0)
+      return string.Empty;
+
     var inputChars = input.ToCharArray();
     var output = new StringBuilder();
 

diff --git a/tests/Smdn.Text.Ondulish/Smdn.Text.Ondulish/KanaUtils.cs b/tests/Smdn.Text.Ondulish/Smdn.Text.Ondulish/KanaUtils.cs
@@ -1,11 +1,13 @@
 // SPDX-FileCopyrightText: 2020 smdn <smdn@smdn.jp>
 // SPDX-License-Identifier: MIT
+using System;
 using NUnit.Framework;
 
 namespace Smdn.Text.Ondulish;
 
 [TestFixture]
 public class KanaUtilsTests {
+  [TestCase("", "")]
   [TestCase("ABC", "ABC")]
   [TestCase("abc", "abc")]
   [TestCase("ＡＢＣ", "ＡＢＣ")]
@@ -22,6 +24,11 @@ public void TestConvertWideHiraganaToKatakana(string input, string expected)
       KanaUtils.ConvertWideHiraganaToKatakana(input)
     );
 
+  [Test]
+  public void TestConvertWideHiraganaToKatakana_ArgumentNull()
+    => Assert.Throws<ArgumentNullException>(() => KanaUtils.ConvertWideHiraganaToKatakana(input: null));
+
+  [TestCase("", "")]
   [TestCase("ABC", "ABC")]
   [TestCase("abc", "abc")]
   [TestCase("ＡＢＣ", "ＡＢＣ")]
@@ -37,4 +44,19 @@ public void TestConvertWideKatakanaToHiragana(string input, string expected)
       expected,
       KanaUtils.ConvertWideKatakanaToHiragana(input)
     );
+
+  [Test]
+  public void TestConvertWideKatakanaToHiragana_ArgumentNull()
+    => Assert.Throws<ArgumentNullException>(() => KanaUtils.ConvertWideKatakanaToHiragana(input: null));
+
+  [TestCase("", "")]
+  public void TestConvertWideKatakanaToNarrowKatakana(string input, string expected)
+    => Assert.AreEqual(
+      expected,
+      KanaUtils.ConvertWideKatakanaToNarrowKatakana(input)
+    );
+
+  [Test]
+  public void TestConvertWideKatakanaToNarrowKatakana_ArgumentNull()
+    => Assert.Throws<ArgumentNullException>(() => KanaUtils.ConvertWideKatakanaToNarrowKatakana(input: null));
 }