Add array filtering

Author: jzbrooks

assertk/src/commonMain/kotlin/assertk/assertions/array.kt

@@ -178,6 +178,34 @@ fun Assert<Array<*>>.containsExactly(vararg elements: Any?) = given { actual ->
     expectedListDiff(elements.asList(), actual.asList())
 }
 
+/**
+ * Asserts the collection contains at least one instance of a given type.
+ *
+ * ```
+ * assertThat(arrayOf<Any>("one", "two", 1)).containsInstanceOf<String>().each {
+ *   it.hasLength(3)
+ * }
+ * ```
+ */
+inline fun <reified T> Assert<Array<*>>.containsInstanceOf(): Assert<List<T>> {
+    return transform("contains subtype of ${T::class}") { actual ->
+        actual.filterIsInstance<T>().also {
+            if (it.isEmpty()) expected("to contain at least one instance of ${T::class} but was ${actual.asList()}")
+        }
+    }
+}
+
+/**
+ * Asserts the collection does not contain an instance of a given type.
+ *
+ * ```
+ * assertThat(arrayOf<Any>("one", "two", 1)).doesNotContainInstanceOf<Double>()
+ * ```
+ */
+inline fun <reified T> Assert<Array<*>>.doesNotContainInstanceOf() = given { actual ->
+    if (actual.any { it is T }) expected("to not contain instances of ${T::class} but was ${actual.asList()}")
+}
+
 /**
  * Asserts on each item in the array. The given lambda will be run for each item.
  *

assertk/src/commonTest/kotlin/test/assertk/assertions/ArrayTest.kt

@@ -322,6 +322,32 @@ class ArrayTest {
     }
     //endregion
 
+    //region containsInstanceOf
+    @Test fun containsInstanceOf_element_present_passes() {
+        assertThat(arrayOf<Any>(1, "two")).containsInstanceOf<String>().single().isEqualTo("two")
+    }
+
+    @Test fun containsInstanceOf_element_missing_fails() {
+        val error = assertFailsWith<AssertionError> {
+            assertThat(arrayOf<Any>(1, "two")).containsInstanceOf<Double>()
+        }
+        assertEquals("expected to contain at least one instance of class kotlin.Double but was [1, two]", error.message)
+    }
+    //endregion
+
+    //region doesNotContainInstanceOf
+    @Test fun doesNotContainInstanceOf_element_present_fails() {
+        val error = assertFailsWith<AssertionError>() {
+            assertThat(arrayOf<Any>(1, "two")).doesNotContainInstanceOf<String>()
+        }
+        assertEquals("expected to not contain instances of class kotlin.String but was [1, two]", error.message)
+    }
+
+    @Test fun doesNotContainInstanceOf_element_missing_passes() {
+        assertThat(arrayOf<Any>(1, "two")).doesNotContainInstanceOf<Double>()
+    }
+    //endregion
+
     //region each
     @Test
     fun each_empty_list_passes() {