Add StringBuilder.appendCodePoint() to kotlin-codepoints-deluxe

Author: cketti

kotlin-codepoints-deluxe/src/commonMain/kotlin/StringBuilderExtensions.kt

@@ -0,0 +1,14 @@
+package de.cketti.codepoints.deluxe
+
+import de.cketti.codepoints.appendCodePoint as intAppendCodePoint
+
+/**
+ * Appends the string representation of the [codePoint] argument to this sequence.
+ *
+ * The argument is appended to the contents of this sequence.
+ * The length of this sequence increases by [CodePoint.charCount].
+ *
+ * The overall effect is exactly as if the argument were converted to a char array by the function
+ * [CodePoint.toChars] and the characters in that array were then appended to this sequence.
+ */
+fun StringBuilder.appendCodePoint(codePoint: CodePoint): StringBuilder = intAppendCodePoint(codePoint.value)

kotlin-codepoints-deluxe/src/commonTest/kotlin/StringBuilderExtensionsTest.kt

@@ -0,0 +1,19 @@
+package de.cketti.codepoints.deluxe
+
+import kotlin.test.assertEquals
+import kotlin.test.Test
+
+class StringBuilderExtensionsTest {
+    @Test
+    fun appendCodePoint() {
+        val actual = buildString {
+            appendCodePoint('a'.toCodePoint())
+            append('b')
+            appendCodePoint('\uFFFF'.toCodePoint())
+            append('c')
+            appendCodePoint("\uD83E\uDD95".codePointAt(0))
+        }
+        
+        assertEquals("ab\uFFFFc\uD83E\uDD95", actual)
+    }
+}