Issue #97: Write directly to a String

src/jvmMain/kotlin/com/github/doyaaaaaken/kotlincsv/client/CsvWriter.kt

@@ -5,6 +5,7 @@ import com.github.doyaaaaaken.kotlincsv.dsl.context.ICsvWriterContext
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import java.io.*
+import java.nio.charset.Charset
 
 /**
  * CSV Writer class, which decides where to write and returns CsvFileWriter class (class for controlling File I/O).
@@ -50,6 +51,12 @@ actual class CsvWriter actual constructor(
         writer.use { it.write() }
     }
 
+    fun writeString(write: ICsvFileWriter.() -> Unit): String {
+        val baos = ByteArrayOutputStream()
+        open(baos, write)
+        return String(baos.toByteArray(), Charset.forName(ctx.charset))
+    }
+
     /**
      * *** ONLY for long-running write case ***
      *
@@ -133,4 +140,11 @@ actual class CsvWriter actual constructor(
     suspend fun writeAllAsync(rows: List<List<Any?>>, ops: OutputStream) {
         open(ops) { writeRows(rows) }
     }
+
+    /**
+     * write all rows to string
+     */
+    fun writeAll(rows: List<List<Any?>>): String {
+        return writeString { writeRows(rows) }
+    }
 }

src/jvmTest/kotlin/com/github/doyaaaaaken/kotlincsv/client/CsvWriterTest.kt

@@ -91,6 +91,20 @@ class CsvWriterTest : WordSpec({
         }
     }
 
+    "writeString method" should {
+        val row1 = listOf("a", "b", null)
+        val row2 = listOf("d", "2", "1.0")
+        val expected = "a,b,\r\nd,2,1.0\r\n"
+
+        "write simple csv data to String" {
+            val actual = csvWriter().writeString {
+                writeRow(row1)
+                writeRow(row2)
+            }
+            actual shouldBe expected
+        }
+    }
+
     "writeAll method without calling `open` method" should {
         val rows = listOf(listOf("a", "b", "c"), listOf("d", "e", "f"))
         val expected = "a,b,c\r\nd,e,f\r\n"
@@ -112,6 +126,11 @@ class CsvWriterTest : WordSpec({
             val actual = readTestFile()
             actual shouldBe expected
         }
+
+        "write data to String" {
+            val actual = csvWriter().writeAll(rows)
+            actual shouldBe expected
+        }
     }
 
     "Customized CsvWriter" should {