add failIf

README.md

@@ -14,56 +14,15 @@
 
 
 # KBox
-KBox is a very small but useful utility library for Kotlin (JVM, Android and JS).
+KBox is a very small but useful utility library for Kotlin (JVM, Android and JS) providing functions which are missing
+in the stdlib such as:
+- failIf
+- takeIf
+- blankToNull
+- isNotNullAndNotEmpty
+- identity
 
-Current extension functions:
-- [`Array/List/Iterable/Sequence.appendtoStringBuilder`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/appendToString.kt#L37)
-    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/main/src/commonMain/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/main/src/commonMain/kotlin/ch/tutteli/kbox/forEachIn.kt#L6)
-  applies the given action to each entry in the given `Iterable`s.
-
-- [`<E> forElementAndEachIn(E, Array/Iterable/Sequence<E>, action: (E) -> Unit)`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/forThisAndForEach.kt#L6)
-  applies the given action to `this` and each entry in Iterable
-
-- [`Iterable<T>.forEachRemaining()`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/forEachRemaining.kt#L9)
-  shortcut for `while(hasNext()) yourLambda(next())`
-
-- [`Array/List.ifWithinBound`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/ifWithinBound.kt#L13)
-  shortcut for `if(index < size){ thenBlock() } else { elseBlock() }`
-
-- [`CharSequence?.isNotNullAndNotEmpty/isNotNullAndNotBlank`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/isNotNullAndNot.kt#L6)  
-
-- [`Array/List/Iterable/Sequence.joinToString`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/joinToString.kt#L31)
-  with the ability to define a different separator for the last separation
-  => handy if you want to form sentences like `a, b and c`
-
-- [`Map<T, T>.mapParents`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/mapParents.kt#L13)
-  maps child-parent relations.
-
-- [`Iterator<T>.mapRemaining/mapRemainingWithCounter`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/mapRemaining.kt#L9)
-  maps remaining entries with the help of a transform function (where `mapRemainingWithCounter` passes a counter variable to the transform function).
-
-- [`Array/Iterable/Sequence.mapWithIndex`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/mapWithIndex.kt#L11)
-
-- [`Sequence.dynamicTraversal`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/dynamicTraversal.kt#L34)
-  allows to iterator over a tree/graph like structure lazily
-
-- [`Iterator.toPeekingIterator()`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/PeekingIteratorUnsynchronized.kt)
-  which allows to have a look what the next element is without consuming it.
-
-- [`varargsToList/glue`](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/varargToList.kt#L11)
-  creates a `List` out of a single `E` and an `Array<E>`.
-
-- [takeIf](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/takeIf.kt#L12) 
-  same behaviour as `takeIf` but as prefix operator and not postfix.
-
-Moreover, the following function might come in handy for you as well:
-- [identity](https://github.com/robstoll/kbox/tree/main/src/commonMain/kotlin/ch/tutteli/kbox/identity.kt)
+and more, see the [Documentation](#documentation) for a full list.
 
 # Installation
 
@@ -72,13 +31,10 @@ KBox is published to maven central.
 ```
 repositories { mavenCentral() }
 dependencies {
-    implementation("ch.tutteli.kbox:kbox-jvm:0.16.0")
+    implementation("ch.tutteli.kbox:kbox:0.16.0")
 }
 ```
 
-Accordingly, you can use `kbox-js` as artifactId instead of `kbox-jvm`
-(or simply `kbox` in case of a MPP project in commonMain).
-
 # Documentation
 
 Visit [https://robstoll.github.io/kbox/kdoc](https://robstoll.github.io/kbox/kdoc/).

src/commonMain/kotlin/ch/tutteli/kbox/failIf.kt

@@ -0,0 +1,11 @@
+package ch.tutteli.kbox
+
+/**
+ * Delegates to [check] but inverting the [predicate], i.e. throws an [IllegalStateException] if predicate is true.
+ *
+ * @param predicate the predicate which defines if the exception should be thrown or not.
+ * @param errorMessage The message which as [IllegalStateException.message]
+ *
+ * @since 1.0.0
+ */
+inline fun failIf(predicate: Boolean, errorMessage: () -> String) = check(predicate.not(), errorMessage)

src/commonTest/kotlin/ch/tutteli/kbox/FailIfTest.kt

@@ -0,0 +1,24 @@
+package ch.tutteli.kbox
+
+import ch.tutteli.atrium.api.fluent.en_GB.messageToContain
+import ch.tutteli.atrium.api.fluent.en_GB.notToThrow
+import ch.tutteli.atrium.api.fluent.en_GB.toThrow
+import ch.tutteli.kbox.atrium.expect
+import kotlin.test.Test
+
+class FailIfTest {
+    @Test
+    fun it_throws_an_IllegalStateException_if_predicate_is_true() {
+        expect {
+            failIf(true) { "my message" }
+        }.toThrow<IllegalStateException> { messageToContain("my message") }
+    }
+
+    @Test
+    fun it_does_not_throw_if_predicate_holds() {
+        expect {
+            failIf(false) { throw UnsupportedOperationException("bla") }
+        }.notToThrow()
+    }
+}
+