Code for BAEL-894 - regular expressions in Kotlin (#3618)

core-kotlin/src/test/kotlin/com/baeldung/kotlin/stdlib/RegexTest.kt

@@ -0,0 +1,128 @@
+package com.baeldung.kotlin.stdlib
+
+import org.junit.Test
+import java.beans.ExceptionListener
+import java.beans.XMLEncoder
+import java.io.*
+import java.lang.Exception
+import kotlin.test.*
+import kotlin.text.RegexOption.*
+
+class RegexTest {
+
+    @Test
+    fun whenRegexIsInstantiated_thenIsEqualToToRegexMethod() {
+        val pattern = """a([bc]+)d?\\"""
+
+        assertEquals(Regex.fromLiteral(pattern).pattern, pattern)
+        assertEquals(pattern, Regex(pattern).pattern)
+        assertEquals(pattern, pattern.toRegex().pattern)
+    }
+
+    @Test
+    fun whenRegexMatches_thenResultIsTrue() {
+        val regex = """a([bc]+)d?""".toRegex()
+
+        assertTrue(regex.containsMatchIn("xabcdy"))
+        assertTrue(regex.matches("abcd"))
+        assertFalse(regex matches "xabcdy")
+    }
+
+    @Test
+    fun givenCompletelyMatchingRegex_whenMatchResult_thenDestructuring() {
+        val regex = """a([bc]+)d?""".toRegex()
+
+        assertNull(regex.matchEntire("xabcdy"))
+
+        val matchResult = regex.matchEntire("abbccbbd")
+
+        assertNotNull(matchResult)
+        assertEquals(matchResult!!.value, matchResult.groupValues[0])
+        assertEquals(matchResult.destructured.toList(), matchResult.groupValues.drop(1))
+        assertEquals("bbccbb", matchResult.destructured.component1())
+        assertNull(matchResult.next())
+    }
+
+    @Test
+    fun givenPartiallyMatchingRegex_whenMatchResult_thenGroups() {
+        val regex = """a([bc]+)d?""".toRegex()
+        var matchResult = regex.find("abcb abbd")
+
+        assertNotNull(matchResult)
+        assertEquals(matchResult!!.value, matchResult.groupValues[0])
+        assertEquals("abcb", matchResult.value)
+        assertEquals(IntRange(0, 3), matchResult.range)
+        assertEquals(listOf("abcb", "bcb"), matchResult.groupValues)
+        assertEquals(matchResult.destructured.toList(), matchResult.groupValues.drop(1))
+
+        matchResult = matchResult.next()
+
+        assertNotNull(matchResult)
+        assertEquals("abbd", matchResult!!.value)
+        assertEquals("bb", matchResult.groupValues[1])
+
+        matchResult = matchResult.next()
+
+        assertNull(matchResult)
+    }
+
+    @Test
+    fun givenPartiallyMatchingRegex_whenMatchResult_thenDestructuring() {
+        val regex = """([\w\s]+) is (\d+) years old""".toRegex()
+        val matchResult = regex.find("Mickey Mouse is 95 years old")
+        val (name, age) = matchResult!!.destructured
+
+        assertEquals("Mickey Mouse", name)
+        assertEquals("95", age)
+    }
+
+    @Test
+    fun givenNonMatchingRegex_whenFindCalled_thenNull() {
+        val regex = """a([bc]+)d?""".toRegex()
+        val matchResult = regex.find("foo")
+
+        assertNull(matchResult)
+    }
+
+    @Test
+    fun givenNonMatchingRegex_whenFindAllCalled_thenEmptySet() {
+        val regex = """a([bc]+)d?""".toRegex()
+        val matchResults = regex.findAll("foo")
+
+        assertNotNull(matchResults)
+        assertTrue(matchResults.none())
+    }
+
+    @Test
+    fun whenReplace_thenReplacement() {
+        val regex = """(red|green|blue)""".toRegex()
+        val beautiful = "Roses are red, Violets are blue"
+        val grim = regex.replace(beautiful, "dark")
+        val shiny = regex.replaceFirst(beautiful, "rainbow")
+
+        assertEquals("Roses are dark, Violets are dark", grim)
+        assertEquals("Roses are rainbow, Violets are blue", shiny)
+    }
+
+    @Test
+    fun whenComplexReplace_thenReplacement() {
+        val regex = """(red|green|blue)""".toRegex()
+        val beautiful = "Roses are red, Violets are blue"
+        val reallyBeautiful = regex.replace(beautiful) {
+            matchResult ->  matchResult.value.toUpperCase() + "!"
+        }
+
+        assertEquals("Roses are RED!, Violets are BLUE!", reallyBeautiful)
+    }
+
+    @Test
+    fun whenSplit_thenList() {
+        val regex = """\W+""".toRegex()
+        val beautiful = "Roses are red, Violets are blue"
+
+        assertEquals(listOf("Roses", "are", "red", "Violets", "are", "blue"), regex.split(beautiful))
+        assertEquals(listOf("Roses", "are", "red", "Violets are blue"), regex.split(beautiful, 4))
+        assertEquals(regex.toPattern().split(beautiful).asList(), regex.split(beautiful))
+    }
+
+}