Added factory method for EitherAssert type

Author: rcardin-lm

src/main/kotlin/in/rcard/assertj/arrowcore/AbstractEitherAssert.kt

@@ -0,0 +1,7 @@
+package `in`.rcard.assertj.arrowcore
+
+import arrow.core.Either
+import org.assertj.core.api.AbstractAssert
+
+abstract class AbstractEitherAssert<SELF : AbstractEitherAssert<SELF, LEFT, RIGHT>, LEFT, RIGHT>(either: Either<LEFT, RIGHT>?) :
+    AbstractAssert<SELF, Either<LEFT, RIGHT>>(either, AbstractEitherAssert::class.java)

src/main/kotlin/in/rcard/assertj/arrowcore/EitherAssert.kt

@@ -0,0 +1,12 @@
+package `in`.rcard.assertj.arrowcore
+
+import arrow.core.Either
+
+class EitherAssert<LEFT, RIGHT>(either: Either<LEFT, RIGHT>?) :
+    AbstractEitherAssert<EitherAssert<LEFT, RIGHT>, LEFT, RIGHT>(either) {
+    companion object {
+        fun <LEFT, RIGHT> assertThat(actual: Either<LEFT, RIGHT>?): EitherAssert<LEFT, RIGHT> {
+            return EitherAssert(actual)
+        }
+    }
+}

src/test/kotlin/in/rcard/assertj/arrowcore/EitherAssert_assertThat_Test.kt

@@ -0,0 +1,28 @@
+package `in`.rcard.assertj.arrowcore
+
+import arrow.core.Either
+import arrow.core.right
+import org.assertj.core.api.BDDAssertions.then
+import org.junit.jupiter.api.Test
+
+class EitherAssert_assertThat_Test {
+    @Test
+    fun `should create an assertion instance when given object is not null`() {
+        // GIVEN
+        val rightValue = 42.right()
+        // WHEN
+        val assertion = EitherAssert.assertThat(rightValue)
+        // THEN
+        then(assertion).isNotNull.isInstanceOf(EitherAssert::class.java)
+    }
+
+    @Test
+    fun `should create an assertion instance when given object is null`() {
+        // GIVEN
+        val rightValue: Either<Nothing, Nothing>? = null
+        // WHEN
+        val assertion = EitherAssert.assertThat(rightValue)
+        // THEN
+        then(assertion).isNotNull.isInstanceOf(EitherAssert::class.java)
+    }
+}