update tests for zig 0.15.1

This removes the need to spin up a web server for each test, instead,
mocking the necessary methods to do everything in line. This will make
the tests much more resilient, and with the remaining WriterGate changes
expected in zig 0.16, I suspect the mocking will be unnecessary in the
next release.

There are several test issues that remain:

* Two skipped tests in signature verification. This is the most
  concerning of the remaining issues
* Serialization of [][]const u8 was probably broken in zig 0.14.1, but
  the new version has surfaced this issue. Warning messages are being
  sent, and this needs to be tracked down
* One of the tests is failing as S3 storage tier extra header is not
  being offered. I'm not sure what in the upgrade might have changed
  this behavior, but this needs to be investigated

src/aws.zig

@@ -85,9 +85,9 @@ pub const Options = struct {
     success_http_code: i64 = 200,
     client: Client,
 
-    /// Used for testing to provide consistent signing. If null, will use current time
-    signing_time: ?i64 = null,
     diagnostics: ?*Diagnostics = null,
+
+    mock: ?awshttp.Mock = null,
 };
 
 pub const Diagnostics = struct {
@@ -298,8 +298,8 @@ pub fn Request(comptime request_action: anytype) type {
                 .region = options.region,
                 .dualstack = options.dualstack,
                 .client = options.client,
-                .signing_time = options.signing_time,
                 .diagnostics = options.diagnostics,
+                .mock = options.mock,
             });
         }
 
@@ -395,7 +395,7 @@ pub fn Request(comptime request_action: anytype) type {
                     .region = options.region,
                     .dualstack = options.dualstack,
                     .sigv4_service_name = Self.service_meta.sigv4_name,
-                    .signing_time = options.signing_time,
+                    .mock = options.mock,
                 },
             );
             defer response.deinit();

src/aws_http.zig

@@ -90,8 +90,37 @@ pub const Options = struct {
     dualstack: bool = false,
     sigv4_service_name: ?[]const u8 = null,
 
-    /// Used for testing to provide consistent signing. If null, will use current time
-    signing_time: ?i64 = null,
+    mock: ?Mock = null,
+};
+
+/// mocking methods for isolated testing
+pub const Mock = struct {
+    /// Used to provide consistent signing
+    signing_time: ?i64,
+    /// context is desiged to be type-erased pointer (@intFromPtr)
+    context: usize = 0,
+    request_fn: *const fn (
+        usize,
+        std.http.Method,
+        std.Uri,
+        std.http.Client.RequestOptions,
+    ) std.http.Client.RequestError!std.http.Client.Request,
+    send_body_complete: *const fn (usize, []u8) std.Io.Writer.Error!void,
+    receive_head: *const fn (usize) std.http.Client.Request.ReceiveHeadError!std.http.Client.Response,
+    reader_decompressing: *const fn (usize) *std.Io.Reader,
+
+    fn request(m: Mock, method: std.http.Method, uri: std.Uri, options: std.http.Client.RequestOptions) std.http.Client.RequestError!std.http.Client.Request {
+        return m.request_fn(m.context, method, uri, options);
+    }
+    fn sendBodyComplete(m: Mock, body: []u8) std.Io.Writer.Error!void {
+        return m.send_body_complete(m.context, body);
+    }
+    fn receiveHead(m: Mock) std.http.Client.Request.ReceiveHeadError!std.http.Client.Response {
+        return m.receive_head(m.context);
+    }
+    fn readerDecompressing(m: Mock) *std.Io.Reader {
+        return m.reader_decompressing(m.context);
+    }
 };
 
 pub const Header = std.http.Header;
@@ -163,9 +192,9 @@ pub const AwsHttp = struct {
             .region = getRegion(service, options.region),
             .service = options.sigv4_service_name orelse service,
             .credentials = creds,
-            .signing_time = options.signing_time,
+            .signing_time = if (options.mock) |m| m.signing_time else null,
         };
-        return try self.makeRequest(endpoint, request, signing_config);
+        return try self.makeRequest(endpoint, request, signing_config, options);
     }
 
     /// makeRequest is a low level http/https function that can be used inside
@@ -184,7 +213,13 @@ pub const AwsHttp = struct {
     /// Content-Length: (length of body)
     ///
     /// Return value is an HttpResult, which will need the caller to deinit().
-    pub fn makeRequest(self: Self, endpoint: EndPoint, request: HttpRequest, signing_config: ?signing.Config) !HttpResult {
+    pub fn makeRequest(
+        self: Self,
+        endpoint: EndPoint,
+        request: HttpRequest,
+        signing_config: ?signing.Config,
+        options: Options,
+    ) !HttpResult {
         var request_cp = request;
 
         log.debug("Request Path: {s}", .{request_cp.path});
@@ -227,13 +262,16 @@ pub const AwsHttp = struct {
         log.debug("Request url: {s}", .{url});
         // TODO: Fix this proxy stuff. This is all a kludge just to compile, but std.http.Client has it all built in now
         var cl = std.http.Client{ .allocator = self.allocator, .https_proxy = if (self.proxy) |*p| @constCast(p) else null };
+        // Not sure this if statement is correct here. deinit seems to assume
+        // that client.request was called at least once, but we don't do that
+        // if we're in a test harness
         defer cl.deinit(); // TODO: Connection pooling
-
         const method = std.meta.stringToEnum(std.http.Method, request_cp.method).?;
 
         // Fetch API in 0.15.1 is insufficient as it does not provide
         // server headers. We'll construct and send the request ourselves
-        var req = try cl.request(method, try std.Uri.parse(url), .{
+        const uri = try std.Uri.parse(url);
+        const req_options: std.http.Client.RequestOptions = .{
             // we need full control over most headers. I wish libraries would do a
             // better job of having default headers as an opt-in...
             .headers = .{
@@ -245,7 +283,13 @@ pub const AwsHttp = struct {
                 .content_type = .omit,
             },
             .extra_headers = headers.items,
-        });
+        };
+
+        var req = if (options.mock) |m|
+            try m.request(method, uri, req_options) // This will call the test harness
+        else
+            try cl.request(method, uri, req_options);
+
         // TODO: Need to test for payloads > 2^14. I believe one of our tests does this, but not sure
         // if (request_cp.body.len > 0) {
         //     // Workaround for https://github.com/ziglang/zig/issues/15626
@@ -267,10 +311,14 @@ pub const AwsHttp = struct {
             // in the chain then does actually modify the body of the request
             // so we'll need to duplicate it here
             const req_body = try self.allocator.dupe(u8, request_cp.body);
+            defer self.allocator.free(req_body); // docs for sendBodyComplete say it flushes, so no need to outlive this
+            if (options.mock) |m|
+                try m.sendBodyComplete(req_body)
+            else
                 try req.sendBodyComplete(req_body);
-        } else try req.sendBodiless();
+        } else if (options.mock == null) try req.sendBodiless();
 
-        var response = try req.receiveHead(&.{});
+        var response = if (options.mock) |m| try m.receiveHead() else try req.receiveHead(&.{});
 
         // TODO: Timeout - is this now above us?
         log.debug(

src/xml_serializer.zig

@@ -413,7 +413,8 @@ test "stringify basic types" {
     {
         const result = try stringifyAlloc(allocator, 3.14, .{});
         defer allocator.free(result);
-        try testing.expectEqualStrings("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<root>3.14e0</root>", result);
+        // zig 0.14.x outputs 3.14e0, but zig 0.15.1 outputs 3.14. Either *should* be acceptable
+        try testing.expectEqualStrings("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<root>3.14</root>", result);
     }
 
     // Test string