[generator] add runtime warning on deprecated context usage (#1323)

### 📝 Description
This PR updates `FunctionDataFetcher` so that it logs a warning when injecting a `GraphQLContext`.  This functionality is [deprecated](https://github.com/ExpediaGroup/graphql-kotlin/blob/master/website/docs/schema-generator/execution/contextual-data.md#interface-injection-deprecated).  Unlike the `GraphQLContext` interface itself, which is annotated `@deprecated, there is no compile or runtime time warning when using `GraphQLContext` interface injection in a query or mutation.

### 🔗 Related Issues
* discussion: #1305
* supersedes: #1306

Co-authored-by: Joel Brown <[email protected]>

Author: dariuszkuc

generator/graphql-kotlin-schema-generator/build.gradle.kts

@@ -6,12 +6,14 @@ val jacksonVersion: String by project
 val kotlinCoroutinesVersion: String by project
 val rxjavaVersion: String by project
 val junitVersion: String by project
+val slf4jVersion: String by project
 
 dependencies {
     api("com.graphql-java:graphql-java:$graphQLJavaVersion")
     api("org.jetbrains.kotlinx:kotlinx-coroutines-reactive:$kotlinCoroutinesVersion")
     api("com.fasterxml.jackson.module:jackson-module-kotlin:$jacksonVersion")
     implementation("io.github.classgraph:classgraph:$classGraphVersion")
+    implementation("org.slf4j:slf4j-api:$slf4jVersion")
     testImplementation("io.reactivex.rxjava3:rxjava:$rxjavaVersion")
     testImplementation("org.junit.jupiter:junit-jupiter-params:$junitVersion")
 }

generator/graphql-kotlin-schema-generator/src/main/kotlin/com/expediagroup/graphql/generator/internal/extensions/kFunctionExtensions.kt

@@ -16,12 +16,21 @@
 
 package com.expediagroup.graphql.generator.internal.extensions
 
+import org.slf4j.Logger
+import org.slf4j.LoggerFactory
 import kotlin.reflect.KFunction
 import kotlin.reflect.KParameter
 import kotlin.reflect.full.valueParameters
 
-internal fun KFunction<*>.getValidArguments(): List<KParameter> =
-    this.valueParameters
-        .filterNot { it.isGraphQLContext() }
-        .filterNot { it.isGraphQLIgnored() }
-        .filterNot { it.isDataFetchingEnvironment() }
+private val logger: Logger = LoggerFactory.getLogger("schemaGenerator")
+
+internal fun KFunction<*>.getValidArguments(parentName: String): List<KParameter> = this.valueParameters.mapNotNull {
+    when {
+        it.isGraphQLIgnored() || it.isDataFetchingEnvironment() -> null
+        it.isGraphQLContext() -> {
+            logger.warn("$parentName.${getFunctionName()} relies on GraphQLContext injection which is deprecated. Please update it to retrieve context from DataFetchingEnvironment instead.")
+            null
+        }
+        else -> it
+    }
+}

generator/graphql-kotlin-schema-generator/src/main/kotlin/com/expediagroup/graphql/generator/internal/types/generateFunction.kt

@@ -45,7 +45,7 @@ internal fun generateFunction(generator: SchemaGenerator, fn: KFunction<*>, pare
         builder.withDirective(it)
     }
 
-    fn.getValidArguments().forEach {
+    fn.getValidArguments(parentName).forEach {
         builder.argument(generateArgument(generator, it))
     }
 

generator/graphql-kotlin-schema-generator/src/test/kotlin/com/expediagroup/graphql/generator/internal/extensions/KFunctionExtensionsKtTest.kt

@@ -26,28 +26,28 @@ internal class KFunctionExtensionsKtTest {
 
     @Test
     fun getValidArguments() {
-        val args = TestingClass::happyPath.getValidArguments()
+        val args = TestingClass::happyPath.getValidArguments("TestingClass")
         assertEquals(expected = 1, actual = args.size)
         assertEquals(expected = "color", actual = args.first().getName())
     }
 
     @Test
     fun `getValidArguments should ignore @GraphQLIgnore`() {
-        val args = TestingClass::ignored.getValidArguments()
+        val args = TestingClass::ignored.getValidArguments("TestingClass")
         assertEquals(expected = 1, actual = args.size)
         assertEquals(expected = "notIgnored", actual = args.first().getName())
     }
 
     @Test
     fun `getValidArguments should ignore GraphQLContext classes`() {
-        val args = TestingClass::context.getValidArguments()
+        val args = TestingClass::context.getValidArguments("TestingClass")
         assertEquals(expected = 1, actual = args.size)
         assertEquals(expected = "notContext", actual = args.first().getName())
     }
 
     @Test
     fun `getValidArguments should ignore DataFetchingEnvironment`() {
-        val args = TestingClass::dataFetchingEnvironment.getValidArguments()
+        val args = TestingClass::dataFetchingEnvironment.getValidArguments("TestingClass")
         assertEquals(expected = 1, actual = args.size)
         assertEquals(expected = "notEnvironment", actual = args.first().getName())
     }