fix: Temporary workaround for conformance client output

When running via a buildpack, the conformance client expects the
output file to be in /workspace, but the working directory is
/workspace/bin. Ideally, the conformance client should have a way of
telling the function where to write the file, but for the moment
this workaround should at least allow it to validate in both contexts.

Author: jskeet

src/Google.Cloud.Functions.ConformanceTests/HttpFunction.cs

@@ -14,6 +14,7 @@
 
 using Google.Cloud.Functions.Framework;
 using Microsoft.AspNetCore.Http;
+using System;
 using System.IO;
 using System.Threading.Tasks;
 
@@ -22,7 +23,12 @@ public class HttpFunction : IHttpFunction
 {
     public async Task HandleAsync(HttpContext context)
     {
-        using var output = File.OpenWrite("function_output.json");
+        // Temporary hack: when running in buildpack validation mode, we need to change
+        // where we write the output.
+        var outputFile = Environment.CurrentDirectory == "/workspace/bin"
+            ? "/workspace/function_output.json" : "function_output.json";
+
+        using var output = File.OpenWrite(outputFile);
         await context.Request.Body.CopyToAsync(output);
     }
 }

src/Google.Cloud.Functions.ConformanceTests/UntypedCloudEventFunction.cs

@@ -15,6 +15,7 @@
 using CloudNative.CloudEvents;
 using CloudNative.CloudEvents.SystemTextJson;
 using Google.Cloud.Functions.Framework;
+using System;
 using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
@@ -24,9 +25,14 @@ public class UntypedCloudEventFunction : ICloudEventFunction
 {
     public async Task HandleAsync(CloudEvent cloudEvent, CancellationToken cancellationToken)
     {
+        // Temporary hack: when running in buildpack validation mode, we need to change
+        // where we write the output.
+        var outputFile = Environment.CurrentDirectory == "/workspace/bin"
+            ? "/workspace/function_output.json" : "function_output.json";
+
         // Write out a structured JSON representation of the CloudEvent
         var formatter = new JsonEventFormatter();
         var bytes = formatter.EncodeStructuredModeMessage(cloudEvent, out var contentType);
-        await File.WriteAllBytesAsync("function_output.json", bytes.ToArray());
+        await File.WriteAllBytesAsync(outputFile, bytes.ToArray());
     }
 }