Make ConnectionPool's retryConnectionEstablishment public (#744)

* Make ConnectionPool's `retryConnectionEstablishment` public

* Unified tests to consistently use `enableFastFailureModeForTesting()`

* Add `retryConnectionEstablishment` as optional parameter to the initializer of `HTTPClient.Configuration.ConnectionPool`

* Reverted change to initializer to prevent API stability breakage

* Add parameterless initializer for `HTTPClient.Configuration.ConnectionPool`

* Moved default values for `HTTPClient.Configuration.ConnectionPool` to the property declarations, so they only have to be specified at one point

* Removed superfluous spaces

Co-authored-by: Cory Benfield <lukasa@apple.com>

* Re-added missing line break

---------

Co-authored-by: Cory Benfield <lukasa@apple.com>

Author: andreasley

Sources/AsyncHTTPClient/HTTPClient.swift

@@ -1012,11 +1012,11 @@ extension HTTPClient.Configuration {
     public struct ConnectionPool: Hashable, Sendable {
         /// Specifies amount of time connections are kept idle in the pool. After this time has passed without a new
         /// request the connections are closed.
-        public var idleTimeout: TimeAmount
+        public var idleTimeout: TimeAmount = .seconds(60)
 
         /// The maximum number of connections that are kept alive in the connection pool per host. If requests with
         /// an explicit eventLoopRequirement are sent, this number might be exceeded due to overflow connections.
-        public var concurrentHTTP1ConnectionsPerHostSoftLimit: Int
+        public var concurrentHTTP1ConnectionsPerHostSoftLimit: Int = 8
 
         /// If true, ``HTTPClient`` will try to create new connections on connection failure with an exponential backoff.
         /// Requests will only fail after the ``HTTPClient/Configuration/Timeout-swift.struct/connect`` timeout exceeded.
@@ -1025,16 +1025,17 @@ extension HTTPClient.Configuration {
         /// - warning: We highly recommend leaving this on.
         /// It is very common that connections establishment is flaky at scale.
         /// ``HTTPClient`` will automatically mitigate these kind of issues if this flag is turned on.
-        var retryConnectionEstablishment: Bool
+        public var retryConnectionEstablishment: Bool = true
 
-        public init(idleTimeout: TimeAmount = .seconds(60)) {
-            self.init(idleTimeout: idleTimeout, concurrentHTTP1ConnectionsPerHostSoftLimit: 8)
+        public init() {}
+
+        public init(idleTimeout: TimeAmount) {
+            self.idleTimeout = idleTimeout
         }
 
         public init(idleTimeout: TimeAmount, concurrentHTTP1ConnectionsPerHostSoftLimit: Int) {
             self.idleTimeout = idleTimeout
             self.concurrentHTTP1ConnectionsPerHostSoftLimit = concurrentHTTP1ConnectionsPerHostSoftLimit
-            self.retryConnectionEstablishment = true
         }
     }
 

Tests/AsyncHTTPClientTests/HTTPClientNIOTSTests.swift

@@ -55,9 +55,8 @@ class HTTPClientNIOTSTests: XCTestCase {
         guard isTestingNIOTS() else { return }
 
         let httpBin = HTTPBin(.http1_1(ssl: true))
-        var config = HTTPClient.Configuration()
-        config.networkFrameworkWaitForConnectivity = false
-        config.connectionPool.retryConnectionEstablishment = false
+        let config = HTTPClient.Configuration()
+            .enableFastFailureModeForTesting()
         let httpClient = HTTPClient(eventLoopGroupProvider: .shared(self.clientGroup),
                                     configuration: config)
         defer {
@@ -84,9 +83,8 @@ class HTTPClientNIOTSTests: XCTestCase {
         guard isTestingNIOTS() else { return }
         #if canImport(Network)
         let httpBin = HTTPBin(.http1_1(ssl: false))
-        var config = HTTPClient.Configuration()
-        config.networkFrameworkWaitForConnectivity = false
-        config.connectionPool.retryConnectionEstablishment = false
+        let config = HTTPClient.Configuration()
+            .enableFastFailureModeForTesting()
 
         let httpClient = HTTPClient(eventLoopGroupProvider: .shared(self.clientGroup),
                                     configuration: config)
@@ -140,9 +138,8 @@ class HTTPClientNIOTSTests: XCTestCase {
         tlsConfig.minimumTLSVersion = .tlsv11
         tlsConfig.maximumTLSVersion = .tlsv1
 
-        var clientConfig = HTTPClient.Configuration(tlsConfiguration: tlsConfig)
-        clientConfig.networkFrameworkWaitForConnectivity = false
-        clientConfig.connectionPool.retryConnectionEstablishment = false
+        let clientConfig = HTTPClient.Configuration(tlsConfiguration: tlsConfig)
+            .enableFastFailureModeForTesting()
         let httpClient = HTTPClient(
             eventLoopGroupProvider: .shared(self.clientGroup),
             configuration: clientConfig