Step 10 - Add request filter in provider test

Author: Phil Endsley

README.md

@@ -921,3 +921,43 @@ FAILURE: Build failed with an exception.
 ```
 
 Oh, dear. _More_ tests are failing. Can you understand why?
+
+## Step 10 - Request Filters on the Provider
+
+Because our pact file has static data in it, our bearer token is now out of date, so when Pact verification passes it to the Provider we get a `401`. There are multiple ways to resolve this - mocking or stubbing out the authentication component is a common one. In our use case, we are going to use a process referred to as _Request Filtering_, using a `RequestFilter`.
+
+_NOTE_: This is an advanced concept and should be used carefully, as it has the potential to invalidate a contract by bypassing its constraints. See https://docs.pact.io/implementation_guides/jvm/provider/junit5/#modifying-the-requests-before-they-are-sent for more details on this.
+
+The approach we are going to take to inject the header is as follows:
+
+1. If we receive any Authorization header, we override the incoming request with a valid (in time) Authorization header, and continue with whatever call was being made
+1. If we don't receive an Authorization header, we do nothing
+
+_NOTE_: We are not considering the `403` scenario in this example.
+
+In `provider/src/test/java/au/com/dius/pactworkshop/provider/ProductPactProviderTest.java`:
+
+```java
+    @TestTemplate
+    @ExtendWith(PactVerificationInvocationContextProvider.class)
+    void verifyPact(PactVerificationContext context, HttpRequest request) {
+        replaceAuthHeader(request);
+        context.verifyInteraction();
+    }
+
+    private void replaceAuthHeader(HttpRequest request) {
+        if (request.containsHeader("Authorization")) {
+            String header = "Bearer " + new SimpleDateFormat("yyyy-MM-dd'T'HH:mm").format(new Date());
+            request.removeHeaders("Authorization");
+            request.addHeader("Authorization", header);
+        }
+    }
+```
+
+We can now run the Provider tests
+
+```console
+❯ ./gradlew provider:test --tests *Pact*Test
+
+BUILD SUCCESSFUL in 1s
+```

provider/src/test/java/au/com/dius/pactworkshop/provider/ProductPactProviderTest.java

@@ -6,6 +6,7 @@
 import au.com.dius.pact.provider.junitsupport.Provider;
 import au.com.dius.pact.provider.junitsupport.State;
 import au.com.dius.pact.provider.junitsupport.loader.PactFolder;
+import org.apache.http.HttpRequest;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.TestTemplate;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -14,7 +15,9 @@
 import org.springframework.boot.web.server.LocalServerPort;
 import org.springframework.test.context.junit.jupiter.SpringExtension;
 
+import java.text.SimpleDateFormat;
 import java.util.Collections;
+import java.util.Date;
 import java.util.List;
 import java.util.Optional;
 
@@ -39,10 +42,19 @@ void setUp(PactVerificationContext context) {
 
     @TestTemplate
     @ExtendWith(PactVerificationInvocationContextProvider.class)
-    void verifyPact(PactVerificationContext context) {
+    void verifyPact(PactVerificationContext context, HttpRequest request) {
+        replaceAuthHeader(request);
         context.verifyInteraction();
     }
 
+    private void replaceAuthHeader(HttpRequest request) {
+        if (request.containsHeader("Authorization")) {
+            String header = "Bearer " + new SimpleDateFormat("yyyy-MM-dd'T'HH:mm").format(new Date());
+            request.removeHeaders("Authorization");
+            request.addHeader("Authorization", header);
+        }
+    }
+
     @State("products exist")
     void toProductsExistState() {
         when(productRepository.fetchAll()).thenReturn(