add blankToNull

README.md

@@ -13,6 +13,9 @@ Current extension functions:
     with the ability to define a different separator for the last separation
     => handy if you want to form sentences like `a, b and c`
 
+- [`CharSequence.blankToNull`](https://github.com/robstoll/kbox/tree/v0.12.1/kbox-common/src/main/kotlin/ch/tutteli/kbox/blanktoNull.kt#L7)
+  returns the same `CharSequence` if not blank, `null` otherwise
+
 - [`forEachIn(Array/Iterable/Sequence<E>, Array/Iterable/Sequence<E>, ..., action: (E) -> Unit)`](https://github.com/robstoll/kbox/tree/v0.12.1/kbox-common/src/main/kotlin/ch/tutteli/kbox/forEachIn.kt#L6)
   applies the given action to each entry in the given `Iterable`s.
 

kbox-common/src/main/kotlin/ch/tutteli/kbox/blankToNull.kt

@@ -0,0 +1,7 @@
+package ch.tutteli.kbox
+
+/**
+ * Returns this [String] if it is not blank, null otherwise.
+ */
+@Suppress("NOTHING_TO_INLINE")
+inline fun <T: CharSequence> T.blankToNull(): T? = if(this.isNotBlank()) this else null

kbox-jvm/src/test/kotlin/ch/tutteli/kbox/BlankToNullSpec.kt

@@ -0,0 +1,26 @@
+package ch.tutteli.kbox
+
+import ch.tutteli.atrium.api.cc.en_GB.toBe
+import ch.tutteli.atrium.assert
+import org.jetbrains.spek.api.Spek
+import org.jetbrains.spek.api.dsl.describe
+
+object BlankToNullSpec : Spek({
+
+    describe("fun ${String::blankToNull.name}") {
+        listOf<Triple<String, CharSequence, CharSequence?>>(
+            Triple("empty String", "", null),
+            Triple("empty StringBuilder", StringBuilder(), null),
+            Triple("String \"   \"", "   ", null),
+            Triple("StringBuilder \"   \"", StringBuilder("   "), null),
+            Triple("String \"  h\"", "  h", "  h"),
+            Triple("StringBuilder \"  h\"", StringBuilder("  h"), StringBuilder("  h")),
+            Triple("String \"h  \"", "h  ", "h  "),
+            Triple("StringBuilder \"h  \"", StringBuilder("h  "), StringBuilder("h  "))
+        ).forEach { (description, value, expected) ->
+            test("given $description, expect $expected") {
+                assert(value.blankToNull().toString()).toBe(expected.toString())
+            }
+        }
+    }
+})

kbox-jvm/src/test/kotlin/ch/tutteli/kbox/IsNotNullAndNotSpec.kt

@@ -12,7 +12,7 @@ object IsNotNullAndNotSpec : Spek({
             Triple("null", null, false),
             Triple("empty String", "", false),
             Triple("empty StringBuilder", StringBuilder(), false),
-            Triple("String \"   \"", StringBuilder("hello"), true),
+            Triple("String \"   \"", "   ", true),
             Triple("StringBuilder \"   \"", StringBuilder("   "), true),
             Triple("String \"hello\"", "hello", true),
             Triple("StringBuilder \"hello\"", StringBuilder("hello"), true)
@@ -28,7 +28,7 @@ object IsNotNullAndNotSpec : Spek({
             Triple("null", null, false),
             Triple("empty String", "", false),
             Triple("empty StringBuilder", StringBuilder(), false),
-            Triple("String \"   \"", StringBuilder("   "), false),
+            Triple("String \"   \"", "   ", false),
             Triple("StringBuilder \"   \"", StringBuilder("   "), false),
             Triple("String \"hello\"", "hello", true),
             Triple("StringBuilder \"hello\"", StringBuilder("hello"), true)