Add client.get operator for features

ktor-client/ktor-client-core/common/src/io/ktor/client/features/HttpClientFeature.kt

@@ -14,25 +14,35 @@ internal val FEATURE_INSTALLED_LIST = AttributeKey<Attributes>("ApplicationFeatu
 /**
  * Base interface representing a [HttpClient] feature.
  */
-interface HttpClientFeature<out TConfig : Any, TFeature : Any> {
+public interface HttpClientFeature<out TConfig : Any, TFeature : Any> {
     /**
      * The [AttributeKey] for this feature.
      */
-    val key: AttributeKey<TFeature>
+    public val key: AttributeKey<TFeature>
 
     /**
      * Builds a [TFeature] by calling the [block] with a [TConfig] config instance as receiver.
      */
-    fun prepare(block: TConfig.() -> Unit = {}): TFeature
+    public fun prepare(block: TConfig.() -> Unit = {}): TFeature
 
     /**
      * Installs the [feature] class for a [HttpClient] defined at [scope].
      */
-    fun install(feature: TFeature, scope: HttpClient)
+    public fun install(feature: TFeature, scope: HttpClient)
 }
 
 /**
- * Try to get a [feature] installed in this client. Returns `null` if the feature was not previously installed.
+ * Try to get the [feature] installed in this client. Returns `null` if the feature was not previously installed.
  */
-fun <B : Any, F : Any> HttpClient.feature(feature: HttpClientFeature<B, F>): F? =
+public fun <B : Any, F : Any> HttpClient.feature(feature: HttpClientFeature<B, F>): F? =
     attributes.getOrNull(FEATURE_INSTALLED_LIST)?.getOrNull(feature.key)
+
+/**
+ * Find the [feature] installed in [HttpClient].
+ *
+ * @throws [IllegalStateException] if [feature] is not installed.
+ */
+public operator fun <B : Any, F: Any> HttpClient.get(feature: HttpClientFeature<B, F>): F {
+    val message = "Feature $feature is not installed. Consider using `install(${feature.key})` in client config first."
+    return feature(feature) ?: error(message)
+}

ktor-client/ktor-client-tests/common/src/io/ktor/client/tests/utils/CommonClientTestUtils.kt

@@ -2,7 +2,7 @@
  * Copyright 2014-2019 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
-@file:Suppress("NO_EXPLICIT_RETURN_TYPE_IN_API_MODE_WARNING")
+@file:Suppress("NO_EXPLICIT_RETURN_TYPE_IN_API_MODE_WARNING", "KDocMissingDocumentation")
 
 package io.ktor.client.tests.utils
 
@@ -16,22 +16,22 @@ import kotlinx.coroutines.*
 /**
  * Web url for tests.
  */
-const val TEST_SERVER: String = "http://127.0.0.1:8080"
+public const val TEST_SERVER: String = "http://127.0.0.1:8080"
 
 /**
  * Websocket server url for tests.
  */
-const val TEST_WEBSOCKET_SERVER: String = "ws://127.0.0.1:8080"
+public const val TEST_WEBSOCKET_SERVER: String = "ws://127.0.0.1:8080"
 
 /**
  * Proxy server url for tests.
  */
-const val HTTP_PROXY_SERVER: String = "http://127.0.0.1:8082"
+public const val HTTP_PROXY_SERVER: String = "http://127.0.0.1:8082"
 
 /**
  * Perform test with selected client [engine].
  */
-fun testWithEngine(
+public fun testWithEngine(
     engine: HttpClientEngine,
     block: suspend TestClientBuilder<*>.() -> Unit
 ) = testWithClient(HttpClient(engine), block)
@@ -59,7 +59,7 @@ private fun testWithClient(
 /**
  * Perform test with selected client engine [factory].
  */
-fun <T : HttpClientEngineConfig> testWithEngine(
+public fun <T : HttpClientEngineConfig> testWithEngine(
     factory: HttpClientEngineFactory<T>,
     loader: ClientLoader? = null,
     block: suspend TestClientBuilder<T>.() -> Unit
@@ -106,30 +106,26 @@ private suspend fun concurrency(level: Int, block: suspend (Int) -> Unit) {
 }
 
 @InternalAPI
-@Suppress("KDocMissingDocumentation")
-class TestClientBuilder<T : HttpClientEngineConfig>(
-    var config: HttpClientConfig<T>.() -> Unit = {},
-    var test: suspend TestInfo.(client: HttpClient) -> Unit = {},
-    var after: suspend (client: HttpClient) -> Unit = {},
-    var repeatCount: Int = 1,
+public class TestClientBuilder<T : HttpClientEngineConfig>(
+    public var config: HttpClientConfig<T>.() -> Unit = {},
+    public var test: suspend TestInfo.(client: HttpClient) -> Unit = {},
+    public var after: suspend (client: HttpClient) -> Unit = {},
+    public var repeatCount: Int = 1,
     var dumpAfterDelay: Long = -1,
     var concurrency: Int = 1
 )
 
 @InternalAPI
-@Suppress("KDocMissingDocumentation")
-fun <T : HttpClientEngineConfig> TestClientBuilder<T>.config(block: HttpClientConfig<T>.() -> Unit) {
+public fun <T : HttpClientEngineConfig> TestClientBuilder<T>.config(block: HttpClientConfig<T>.() -> Unit) {
     config = block
 }
 
 @InternalAPI
-@Suppress("KDocMissingDocumentation")
-fun TestClientBuilder<*>.test(block: suspend TestInfo.(client: HttpClient) -> Unit) {
+public fun TestClientBuilder<*>.test(block: suspend TestInfo.(client: HttpClient) -> Unit) {
     test = block
 }
 
 @InternalAPI
-@Suppress("KDocMissingDocumentation")
-fun TestClientBuilder<*>.after(block: suspend (client: HttpClient) -> Unit): Unit {
+public fun TestClientBuilder<*>.after(block: suspend (client: HttpClient) -> Unit): Unit {
     after = block
 }