check valid api path, resolves #1

Author: hauner

src/main/kotlin/io/openapiprocessor/core/parser/NoOpenApiException.kt

@@ -0,0 +1,13 @@
+/*
+ * Copyright 2021 https://github.com/openapi-processor/openapi-processor-core
+ * PDX-License-Identifier: Apache-2.0
+ */
+
+package io.openapiprocessor.core.parser
+
+class NoOpenApiException : RuntimeException() {
+
+    override val message: String
+        get() = "can't find OpenAPI description. Is the option 'apiPath' set?"
+
+}

src/main/kotlin/io/openapiprocessor/core/parser/Parser.kt

@@ -30,7 +30,7 @@ class Parser {
     private val log: Logger = LoggerFactory.getLogger(this.javaClass.name)
 
     fun parse(processorOptions: Map<String, *>): OpenApi {
-        val apiPath: String = processorOptions["apiPath"].toString()
+        val apiPath: String = processorOptions["apiPath"]?.toString() ?: throw NoOpenApiException()
 
         when(val parser= processorOptions["parser"]?.toString()) {
             ParserType.SWAGGER.name -> {

src/test/kotlin/io/openapiprocessor/core/parser/ParserSpec.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2021 https://github.com/openapi-processor/openapi-processor-core
+ * PDX-License-Identifier: Apache-2.0
+ */
+
+package io.openapiprocessor.core.parser
+
+import io.kotest.assertions.throwables.shouldThrow
+import io.kotest.core.spec.style.StringSpec
+
+class ParserSpec: StringSpec({
+
+    "throws if apiPath is not set" {
+        val parser = Parser()
+
+        shouldThrow<NoOpenApiException> {
+            parser.parse(emptyMap<String, Any>())
+        }
+    }
+
+})