[stdlib] KT-80748 add ensurePrefix and ensureSuffix extension functions

Author: Julian R

libraries/stdlib/src/kotlin/text/Strings.kt

@@ -634,7 +634,7 @@ public fun String.removePrefix(prefix: CharSequence): String {
  * If this char sequence does not start with the given [prefix], returns a new char sequence
  * with the prefix added. Otherwise, returns a new char sequence with the same characters.
  */
-public fun CharSequence.appendPrefix(prefix: CharSequence): CharSequence {
+public fun CharSequence.ensurePrefix(prefix: CharSequence): CharSequence {
     if (!this.startsWith(prefix)) {
         return prefix.toString() + this.toString()
     }
@@ -645,7 +645,7 @@ public fun CharSequence.appendPrefix(prefix: CharSequence): CharSequence {
  * If this string does not start with the given [prefix], returns a copy of this string
  * with the prefix added. Otherwise, returns this string.
  */
-public fun String.appendPrefix(prefix: CharSequence): String {
+public fun String.ensurePrefix(prefix: CharSequence): String {
     if (!this.startsWith(prefix)) {
         return prefix.toString() + this
     }
@@ -678,7 +678,7 @@ public fun String.removeSuffix(suffix: CharSequence): String {
  * If the char sequence not ends with the given [suffix], returns a copy of this string
  * with the suffix appended. Otherwise, returns a new char sequence with the same characters.
  */
-public fun CharSequence.appendSuffix(suffix: CharSequence): CharSequence {
+public fun CharSequence.ensureSuffix(suffix: CharSequence): CharSequence {
     if (!endsWith(suffix)) {
         return this.toString() + suffix.toString()
     }
@@ -689,7 +689,7 @@ public fun CharSequence.appendSuffix(suffix: CharSequence): CharSequence {
  * If the string not ends with the given [suffix], returns a copy of this string
  * with the suffix appended. Otherwise, returns this string.
  */
-public fun String.appendSuffix(suffix: CharSequence): String {
+public fun String.ensureSuffix(suffix: CharSequence): String {
     if (!endsWith(suffix)) {
         return this + suffix.toString()
     }

libraries/stdlib/test/text/StringTest.kt

@@ -596,16 +596,16 @@ class StringTest {
         assertEquals("sample", "sample".removeSuffix(""))
     }
 
-    @Test fun appendSuffix() = withOneCharSequenceArg("fix") { suffix ->
-        assertEquals("suffix", "suf".appendSuffix(suffix), "Appends suffix")
-        assertEquals("suffix", "suffix".appendSuffix(suffix))
-        assertEquals("sample", "sample".appendSuffix(""))
+    @Test fun ensureSuffix() = withOneCharSequenceArg("fix") { suffix ->
+        assertEquals("suffix", "suf".ensureSuffix(suffix), "Appends suffix")
+        assertEquals("suffix", "suffix".ensureSuffix(suffix))
+        assertEquals("sample", "sample".ensureSuffix(""))
     }
 
-    @Test fun appendPrefix() = withOneCharSequenceArg("suf") { prefix ->
-        assertEquals("suffix", "fix".appendSuffix(prefix), "Appends prefix")
-        assertEquals("suffix", "suffix".appendSuffix(prefix))
-        assertEquals("sample", "sample".appendSuffix(""))
+    @Test fun ensurePrefix() = withOneCharSequenceArg("suf") { prefix ->
+        assertEquals("suffix", "fix".ensurePrefix(prefix), "Appends prefix")
+        assertEquals("suffix", "suffix".ensurePrefix(prefix))
+        assertEquals("sample", "sample".ensurePrefix(""))
     }
 
     @Test fun removeSurrounding() = withOneCharSequenceArg { arg1 ->
@@ -640,22 +640,22 @@ class StringTest {
         assertContentEquals("sample", "sample".removeSuffix(""))
     }
 
-    @Test fun appendPrefixCharSequence() = withTwoCharSequenceArgs { arg1, arg2 ->
-        fun String.appendPrefix(prefix: String) = arg1(this).appendPrefix(arg2(prefix))
+    @Test fun ensurePrefixCharSequence() = withTwoCharSequenceArgs { arg1, arg2 ->
+        fun String.ensurePrefix(prefix: String) = arg1(this).ensurePrefix(arg2(prefix))
         val prefix = "suf"
 
-        assertContentEquals("suffix", "fix".appendPrefix(prefix), "Appends prefix")
-        assertContentEquals("suffix", "suffix".appendPrefix(prefix))
-        assertContentEquals("sample", "sample".appendPrefix(""))
+        assertContentEquals("suffix", "fix".ensurePrefix(prefix), "Appends prefix")
+        assertContentEquals("suffix", "suffix".ensurePrefix(prefix))
+        assertContentEquals("sample", "sample".ensurePrefix(""))
     }
 
-    @Test fun appendSuffixCharSequence() = withTwoCharSequenceArgs { arg1, arg2 ->
-        fun String.appendSuffix(suffix: String) = arg1(this).appendSuffix(arg2(suffix))
+    @Test fun ensureSuffixCharSequence() = withTwoCharSequenceArgs { arg1, arg2 ->
+        fun String.ensureSuffix(suffix: String) = arg1(this).ensureSuffix(arg2(suffix))
         val suffix = "fix"
 
-        assertContentEquals("suffix", "suf".appendSuffix(suffix), "Appends suffix")
-        assertContentEquals("suffix", "suffix".appendSuffix(suffix))
-        assertContentEquals("sample", "sample".appendSuffix(""))
+        assertContentEquals("suffix", "suf".ensureSuffix(suffix), "Appends suffix")
+        assertContentEquals("suffix", "suffix".ensureSuffix(suffix))
+        assertContentEquals("sample", "sample".ensureSuffix(""))
     }
 
     @Test fun removeSurroundingCharSequence() = withTwoCharSequenceArgs { arg1, arg2 ->