Add minimal test for AndroidBuildApi

Exercises FileReader directly using FakeHttpClient and verifies
that the download URL fetch targets the correct V4 API endpoint.

Assisted-by: Jetski:Gemini Next

Author: Databean

base/cvd/cuttlefish/host/libs/web/BUILD.bazel

@@ -83,6 +83,21 @@ cf_cc_test(
     ],
 )
 
+cf_cc_test(
+    name = "android_build_api_test",
+    srcs = ["android_build_api_test.cpp"],
+    deps = [
+        "//cuttlefish/host/libs/web:android_build",
+        "//cuttlefish/host/libs/web:android_build_api",
+        "//cuttlefish/host/libs/web:android_build_url",
+        "//cuttlefish/host/libs/web/http_client",
+        "//cuttlefish/host/libs/web/http_client:fake_http_client",
+        "//cuttlefish/host/libs/zip/libzip_cc:seekable_source",
+        "//cuttlefish/result",
+        "//cuttlefish/result:result_matchers",
+    ],
+)
+
 cf_cc_library(
     name = "android_build_url",
     srcs = ["android_build_url.cpp"],

base/cvd/cuttlefish/host/libs/web/android_build_api_test.cpp

@@ -0,0 +1,70 @@
+//
+// Copyright (C) 2026 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "cuttlefish/host/libs/web/android_build_api.h"
+
+#include <string>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+#include "cuttlefish/host/libs/web/android_build.h"
+#include "cuttlefish/host/libs/web/android_build_url.h"
+#include "cuttlefish/host/libs/web/http_client/fake_http_client.h"
+#include "cuttlefish/host/libs/web/http_client/http_client.h"
+#include "cuttlefish/host/libs/zip/libzip_cc/seekable_source.h"
+#include "cuttlefish/result/result.h"
+#include "cuttlefish/result/result_matchers.h"
+
+namespace cuttlefish {
+namespace {
+
+TEST(AndroidBuildApiTest, FileReader) {
+  FakeHttpClient http_client;
+  AndroidBuildUrl build_url("https://androidbuild-pa.googleapis.com/v4", "",
+                            "");
+  AndroidBuildApi api(http_client, build_url);
+
+  http_client.SetResponse("{\"signedUrl\": \"http://zip-url\"}", "/url");
+
+  HttpResponse<std::string> res = {
+      .data = "abc",
+      .http_code = 200,
+      .headers =
+          {
+              {"accept-ranges", "bytes"},
+              {"content-length", "3"},
+          },
+  };
+  http_client.SetResponse(res, "http://zip-url");
+
+  Build build = DeviceBuild{.id = "123", .target = "test"};
+  Result<SeekableZipSource> source = api.FileReader(build, "a.zip");
+  ASSERT_THAT(source, IsOk());
+
+  Result<SeekingZipSourceReader> reader = source->Reader();
+  ASSERT_THAT(reader, IsOk());
+
+  char buf[4] = {};
+  ASSERT_THAT(reader->Read(buf, 3), IsOkAndValue(3));
+  EXPECT_STREQ(buf, "abc");
+
+  EXPECT_TRUE(http_client.RequestMade(
+      "https://androidbuild-pa.googleapis.com/v4/builds/123/test/attempts/"
+      "latest/artifacts/a.zip/url"));
+}
+
+}  // namespace
+}  // namespace cuttlefish