Added API unit tests

library/build.gradle

@@ -89,6 +89,8 @@ dokka {
 dependencies {
     compile fileTree(dir: 'libs', include: ['*.jar'])
     testCompile 'junit:junit:4.12'
+    testCompile 'org.robolectric:robolectric:3.5.1'
+
     compile 'com.android.support:support-annotations:27.0.0'
     compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
 }

library/src/test/java/com/antonpotapov/PoliwhirlApiTests.kt

@@ -0,0 +1,60 @@
+package com.antonpotapov
+
+import android.graphics.Bitmap
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+
+/**
+ * ======================================
+ * Created by awesome potapov on 30.10.17.
+ * ======================================
+ */
+@RunWith(RobolectricTestRunner::class)
+class PoliwhirlApiTests {
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testApiAccuracy1() {
+        Poliwhirl().setAccuracy(0).generate(Bitmap.createBitmap(10, 10, Bitmap.Config.ARGB_8888))
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testApiAccuracy2() {
+        Poliwhirl().setAccuracy(11).generate(Bitmap.createBitmap(10, 10, Bitmap.Config.ARGB_8888))
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testApiDistance() {
+        Poliwhirl().setMinAvailableColorDistance(-1)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testApiHorizontalBorder1() {
+        Poliwhirl().setHorizontalBorderSizeDivideMultiplier(0)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testApiHorizontalBorder2() {
+        Poliwhirl().setHorizontalBorderSizeDivideMultiplier(1)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testApiVerticalBorder1() {
+        Poliwhirl().setVerticalBorderSizeDivideMultiplier(0)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testApiVerticalBorder2() {
+        Poliwhirl().setVerticalBorderSizeDivideMultiplier(1)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testApiBorder1() {
+        Poliwhirl().setBorderSizeDivideMultiplier(0)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun testApiBorder2() {
+        Poliwhirl().setBorderSizeDivideMultiplier(1)
+    }
+}