Adopt swift-testing for MethodConfig tests (#2055)

Motivation:

swift-testing has a number of advantages over XCTest (parameterisation,
organisation, failure messages etc.), we should start using it instead
of XCTest.

Modifications:

- Convert the MethodConfig coding tests
- Fixed a couple of bugs found by additional testing

Results:

Fewer bugs, better tests

Author: glbrntt

Package@swift-6.swift

@@ -415,6 +415,9 @@ extension Target {
         .protobuf,
         .testing,
       ],
+      resources: [
+        .copy("Configuration/Inputs")
+      ],
       swiftSettings: [.swiftLanguageMode(.v6), .enableUpcomingFeature("ExistentialAny")]
     )
   }

Sources/GRPCCore/Configuration/MethodConfig.swift

@@ -453,6 +453,7 @@ extension MethodConfig: Codable {
   public func encode(to encoder: any Encoder) throws {
     var container = encoder.container(keyedBy: CodingKeys.self)
     try container.encode(self.names, forKey: .name)
+    try container.encodeIfPresent(self.waitForReady, forKey: .waitForReady)
     try container.encodeIfPresent(
       self.timeout.map { GoogleProtobufDuration(duration: $0) },
       forKey: .timeout

Tests/GRPCCoreTests/Configuration/Inputs/method_config.hedging_policy.invalid.max_attempts.json

@@ -0,0 +1,5 @@
+{
+  "maxAttempts": 1,
+  "hedgingDelay": "1s",
+  "nonFatalStatusCodes": ["ABORTED"]
+}

Tests/GRPCCoreTests/Configuration/Inputs/method_config.hedging_policy.json

@@ -0,0 +1,5 @@
+{
+  "maxAttempts": 3,
+  "hedgingDelay": "1s",
+  "nonFatalStatusCodes": ["ABORTED"]
+}

Tests/GRPCCoreTests/Configuration/Inputs/method_config.json

@@ -0,0 +1,12 @@
+{
+  "name": [
+    {
+      "service": "echo.Echo",
+      "method": "Get"
+    }
+  ],
+  "waitForReady": true,
+  "timeout": "1s",
+  "maxRequestMessageBytes": 1024,
+  "maxResponseMessageBytes": 2048
+}

Tests/GRPCCoreTests/Configuration/Inputs/method_config.name.empty.json

@@ -0,0 +1 @@
+{}

Tests/GRPCCoreTests/Configuration/Inputs/method_config.name.full.json

@@ -0,0 +1,4 @@
+{
+  "service": "foo.bar",
+  "method": "baz"
+}

Tests/GRPCCoreTests/Configuration/Inputs/method_config.name.service_only.json

@@ -0,0 +1,3 @@
+{
+  "service": "foo.bar"
+}

Tests/GRPCCoreTests/Configuration/Inputs/method_config.retry_policy.invalid.backoff_multiplier.json

@@ -0,0 +1,7 @@
+{
+  "maxAttempts": 3,
+  "initialBackoff": "1s",
+  "maxBackoff": "3s",
+  "backoffMultiplier": -1.6,
+  "retryableStatusCodes": ["ABORTED", "UNAVAILABLE"]
+}

Tests/GRPCCoreTests/Configuration/Inputs/method_config.retry_policy.invalid.initial_backoff.json

@@ -0,0 +1,7 @@
+{
+  "maxAttempts": 3,
+  "initialBackoff": "0s",
+  "maxBackoff": "3s",
+  "backoffMultiplier": 1.6,
+  "retryableStatusCodes": ["ABORTED", "UNAVAILABLE"]
+}