[📚docs] revisit docs 3/3 Testing + Advanced (#6096)

* rework the "testing" section

* link to nullability higher up

docs/source/advanced/experimental-websockets.mdx

@@ -111,34 +111,4 @@ The above uses the default retry algorithm:
 * Wait until the network is available if you configured a [NetworkMonitor](network-connectivity).
 * Or use exponential backoff else.
 
-To customize the retry logic more, use `retryOnErrorInterceptor`:
-
-```kotlin
-val apolloClient = ApolloClient.Builder()
-    .retryOnErrorInterceptor(MyRetryOnErrorInterceptor())
-    .build()
-
-class MyRetryOnErrorInterceptor : ApolloInterceptor {
-  object RetryException : Exception()
-
-  override fun <D : Operation.Data> intercept(request: ApolloRequest<D>, chain: ApolloInterceptorChain): Flow<ApolloResponse<D>> {
-    var attempt = 0
-    return chain.proceed(request).onEach {
-      if (request.retryOnError == true && it.exception != null && it.exception is ApolloNetworkException) {
-        throw RetryException
-      } else {
-        attempt = 0
-      }
-    }.retryWhen { cause, _ ->
-      if (cause is RetryException) {
-        attempt++
-        delay(2.0.pow(attempt).seconds)
-        true
-      } else {
-        // Not a RetryException, probably a programming error, pass it through
-        false
-      }
-    }
-  }
-}
-```
+To customize the retry logic more, see the [network monitoring page](../advanced/network-connectivity#customizing-the-retry-algorithm).

docs/source/advanced/network-connectivity.mdx

@@ -54,27 +54,34 @@ When a `NetworkMonitor` is configured, `retryOnError` uses `NetworkMonitor.waitF
 
 ### Customizing the retry algorithm
 
-You can customize the retry algorithm further by defining you own interceptor:
+You can customize the retry algorithm further by defining your own interceptor:
 
 ```kotlin
-internal class MyRetryInterceptor(private val networkMonitor: NetworkMonitor?): ApolloInterceptor {
+val apolloClient = ApolloClient.Builder()
+    .retryOnErrorInterceptor(MyRetryOnErrorInterceptor())
+    .build()
+
+class MyRetryOnErrorInterceptor : ApolloInterceptor {
+  object RetryException : Exception()
+
   override fun <D : Operation.Data> intercept(request: ApolloRequest<D>, chain: ApolloInterceptorChain): Flow<ApolloResponse<D>> {
-    // Disable Apollo's built-in retry mechanism
-    val newRequest = request.newBuilder().retryOnError(false).build()
-    return chain.proceed(newRequest)
-        .onEach { 
-          if (it.exception != null && it.exception.shouldRetry()) {
-            throw RetryException
-          }
-        }.retryWhen { cause, _-> 
-          if (cause is RetryException) {
-            // Add your logic here
-            true
-          } else {
-            // Programming error, re-throw it
-            false
-          }
-        }
+    var attempt = 0
+    return chain.proceed(request).onEach {
+      if (request.retryOnError == true && it.exception != null && it.exception is ApolloNetworkException) {
+        throw RetryException
+      } else {
+        attempt = 0
+      }
+    }.retryWhen { cause, _ ->
+      if (cause is RetryException) {
+        attempt++
+        delay(2.0.pow(attempt).seconds)
+        true
+      } else {
+        // Not a RetryException, probably a programming error, pass it through
+        false
+      }
+    }
   }
 }
 ```

docs/source/config.json

@@ -62,11 +62,11 @@
       "Batching operations": "/advanced/query-batching"
     },
     "Development & Testing": {
-      "Android Studio plugin": "/testing/android-studio-plugin",
       "Testing overview": "/testing/overview",
       "Mocking HTTP responses": "/testing/mocking-http-responses",
       "Mocking GraphQL responses": "/testing/mocking-graphql-responses",
       "Data builders": "/testing/data-builders",
+      "Android Studio plugin": "/testing/android-studio-plugin",
       "Apollo Debug Server": "/testing/apollo-debug-server"
     },
     "Advanced": {

docs/source/essentials/errors.mdx

@@ -2,6 +2,12 @@
 title: Error handling
 ---
 
+<Note>
+
+Starting with version 4.0.0, Apollo Kotlin offers a way to handle errors automatically at parsing time. Fields that are nullable only for error purposes can also be generated as non-null in Kotlin. Read ["handling nullability"](../advanced/nullability) for more details.
+
+</Note>
+
 ## `ApolloResponse` 
 
 Use `ApolloResponse.data` to check if the server returned data:
@@ -130,9 +136,4 @@ For an example, it is possible for a person to not have a starship:
 }
 ```
 
-In that case, `starship` is a true null and not an error. 
-
-### Handling GraphQL errors at parsing time
-
-Because making the difference between true nulls and error nulls is cumbersome, Apollo Kotlin offers a way to handle errors automatically at parsing time. Fields that are nullable only for error purposes can also be generated as non-null in Kotlin. Read ["handling nullability"](../advanced/nullability) for more details.
-
+In that case, `starship` is a true null and not an error.

docs/source/testing/mocking-graphql-responses.mdx

@@ -10,8 +10,6 @@ title: Mocking GraphQL responses
 
 `QueueTestNetworkTransport` is a high-level test API that lets you specify the GraphQL responses that are returned by your `ApolloClient` instance.
 
-> See also [`MockServer`](./mocking-http-responses), which creates a full HTTP server and helps test specific server behaviors, such as error cases, HTTP headers, and timeouts.
-
 Add the dependency to your project's `build.gradle` file:
 
 ```kotlin title="build.gradle[.kts]"

docs/source/testing/mocking-http-responses.mdx

@@ -10,7 +10,12 @@ title: Mocking HTTP responses (experimental)
 
 `MockServer` implements an HTTP server that you can use to mock responses. It's useful for testing specific server behaviors, such as error cases, HTTP headers, and timeouts. Using it requires minimal changes to your production code, because you only need to change your `serverUrl`.
 
-> See also [`TestNetworkTransport`](./mocking-graphql-responses), which handles mocking at the GraphQL level instead of the HTTP level.
+
+<Note>
+
+Apollo Kotlin MockServer is developed in a separate repository. Head to /~https://github.com/apollographql/apollo-kotlin-mockserver for API docs and comprehensive documentation.
+
+</Note>
 
 Add the dependency to your project's `build.gradle` file:
 

docs/source/testing/overview.mdx

@@ -7,8 +7,8 @@ Apollo Kotlin provides the following tools to help with testing your code:
 
 - [`MockServer`](./mocking-http-responses) (experimental): an HTTP server that you can use to mock any responses
 - [`TestNetworkTransport`](./mocking-graphql-responses) (experimental): lets you specify the GraphQL responses returned by `ApolloClient`
-- [Test builders](./test-builders) (experimental): help instantiate your model classes by providing a DSL
+- [Data builders](./data-builders) (experimental): help instantiate your model classes by providing a DSL
 
 `MockServer` creates a full HTTP server. It requires minimal changes to your production code (you only need to change `serverUrl`), which means you can use the same `ApolloClient` for tests and production. `MockServer` is also useful for testing specific server behaviors, such as error cases, HTTP headers, and timeouts.
 
-`TestNetworkTransport` bypasses HTTP calls altogether and returns predefined GraphQL responses. It requires more modifications to your production code, but you can use it in lighter tests that don't need to create a server. You can use test builders to instantiate the data in the responses.
+`TestNetworkTransport` bypasses HTTP calls altogether and returns predefined GraphQL responses. It requires more modifications to your production code, but you can use it in lighter tests that don't need to create a server. You can use data builders to instantiate the data in the responses.