refactor(changeprovider): Read Phabricator diffs through platform/conduit

platform/conduit/README.md

@@ -45,3 +45,7 @@ Every error is wrapped with the method name.
 
 - **Per-method wrappers.** Each caller keeps its own typed request and result for the methods it calls, and decides what a missing object means for it. A method only one caller uses never lands in this package.
 - **Retries, logging and metrics.** Retry decisions belong to the consumer's error classifiers, and callers already log and record metrics in their own scope.
+
+## Who uses it
+
+- `submitqueue/extension/changeprovider/phabricator` reads diffs with `differential.querydiffs`; the orchestrator's wiring builds its client from the configured endpoint and token.

service/submitqueue/orchestrator/server/BUILD.bazel

@@ -20,6 +20,7 @@ go_library(
         "//api/base/hook:go_default_library",
         "//api/submitqueue/orchestrator/protopb:go_default_library",
         "//platform/buildkite:go_default_library",
+        "//platform/conduit:go_default_library",
         "//platform/errs:go_default_library",
         "//platform/errs/generic:go_default_library",
         "//platform/errs/git:go_default_library",

service/submitqueue/orchestrator/server/profiles.go

@@ -29,6 +29,7 @@ import (
 	"context"
 
 	platformbuildkite "github.com/uber/submitqueue/platform/buildkite"
+	"github.com/uber/submitqueue/platform/conduit"
 	"github.com/uber/submitqueue/platform/extension/gitworkspace"
 	gitworkspacelocal "github.com/uber/submitqueue/platform/extension/gitworkspace/local"
 	gitrepo "github.com/uber/submitqueue/platform/git/repo"
@@ -596,15 +597,13 @@ func (b *profileBuilder) newPhabChangeProvider(cfg phabProviderConfig, where str
 		return nil, fmt.Errorf("%s: failed to build Phabricator HTTP client: %w", where, err)
 	}
 	client.Timeout = timeoutOr(cfg.Timeout, defaultHTTPTimeout)
-
-	baseTransport := client.Transport.(*http.BaseURLTransport)
-	baseTransport.Next = &apiTokenTransport{token: token, next: baseTransport.Next}
+	conduitClient := conduit.NewClient(client, token)
 
 	scope := b.scope.SubScope("changeprovider.phabricator")
 	return func(c changeprovider.Config) changeprovider.ChangeProvider {
 		return phabprovider.NewProvider(phabprovider.Params{
 			Config:       c,
-			HTTPClient:   client,
+			Conduit:      conduitClient,
 			Logger:       b.logger.Sugar(),
 			MetricsScope: scope,
 		})
@@ -813,18 +812,3 @@ func (b *profileBuilder) githubClient(baseURL, timeout, token, where string) (*n
 	}
 	return client, nil
 }
-
-// apiTokenTransport injects a Phabricator API token as a query parameter in
-// each request.
-type apiTokenTransport struct {
-	token string
-	next  nethttp.RoundTripper
-}
-
-func (t *apiTokenTransport) RoundTrip(req *nethttp.Request) (*nethttp.Response, error) {
-	r := req.Clone(req.Context())
-	q := r.URL.Query()
-	q.Set("api.token", t.token)
-	r.URL.RawQuery = q.Encode()
-	return t.next.RoundTrip(r)
-}

submitqueue/extension/changeprovider/phabricator/BUILD.bazel

@@ -3,15 +3,15 @@ load("@rules_go//go:def.bzl", "go_library", "go_test")
 go_library(
     name = "go_default_library",
     srcs = [
-        "conduit.go",
         "convert.go",
         "provider.go",
+        "querydiffs.go",
     ],
     importpath = "github.com/uber/submitqueue/submitqueue/extension/changeprovider/phabricator",
     visibility = ["//visibility:public"],
     deps = [
         "//platform/base/change/phabricator:go_default_library",
-        "//platform/http:go_default_library",
+        "//platform/conduit:go_default_library",
         "//platform/metrics:go_default_library",
         "//submitqueue/entity:go_default_library",
         "//submitqueue/extension/changeprovider:go_default_library",
@@ -23,14 +23,15 @@ go_library(
 go_test(
     name = "go_default_test",
     srcs = [
-        "conduit_test.go",
         "convert_test.go",
         "provider_test.go",
+        "querydiffs_test.go",
     ],
     embed = [":go_default_library"],
     deps = [
         "//platform/base/change:go_default_library",
         "//platform/base/change/phabricator:go_default_library",
+        "//platform/conduit:go_default_library",
         "//platform/errs:go_default_library",
         "//platform/errs/http:go_default_library",
         "//platform/http:go_default_library",