Avoid network requests while resolving versions when possible.

sdk/lib/_internal/pub/test/get/hosted/does_no_network_requests_when_possible_test.dart

Index: sdk/lib/_internal/pub/test/get/hosted/does_no_network_requests_when_possible_test.dart
diff --git a/sdk/lib/_internal/pub/test/get/hosted/cached_pubspec_test.dart b/sdk/lib/_internal/pub/test/get/hosted/does_no_network_requests_when_possible_test.dart
similarity index 58%
copy from sdk/lib/_internal/pub/test/get/hosted/cached_pubspec_test.dart
copy to sdk/lib/_internal/pub/test/get/hosted/does_no_network_requests_when_possible_test.dart
index 3024336930cdfb591243deb9c1d25ef57c564b72..44532fd01b92c00beac6bcacbcd811737f8a6356 100644
--- a/sdk/lib/_internal/pub/test/get/hosted/cached_pubspec_test.dart
+++ b/sdk/lib/_internal/pub/test/get/hosted/does_no_network_requests_when_possible_test.dart
@@ -12,10 +12,16 @@ import '../../test_pub.dart';
 main() {
   initConfig();
 
-  integration('does not request a pubspec for a cached package', () {
-    servePackages([packageMap("foo", "1.2.3")]);
+  integration('does not request versions if the lockfile is up to date', () {
+    servePackages([
+      packageMap("foo", "1.0.0"),
+      packageMap("foo", "1.1.0"),
+      packageMap("foo", "1.2.0")
+    ]);
 
-    d.appDir({"foo": "1.2.3"}).create();
+    d.appDir({
+      "foo": "any"
+    }).create();
 
     // Get once so it gets cached.
     pubGet();
@@ -24,15 +30,16 @@ main() {
     // the initial get.
     getRequestedPaths();
 
-    d.cacheDir({"foo": "1.2.3"}).validate();
-    d.packagesDir({"foo": "1.2.3"}).validate();
-
     // Run the solver again now that it's cached.
     pubGet();
 
-    // The get should not have requested the pubspec since it's local already.
+    d.cacheDir({"foo": "1.2.0"}).validate();
+    d.packagesDir({"foo": "1.2.0"}).validate();
+
+    // The get should not have done any network requests since the lock file is
+    // up to date.
     getRequestedPaths().then((paths) {
-      expect(paths, isNot(contains("packages/foo/versions/1.2.3.yaml")));
+      expect(paths, isEmpty);
     });
   });
 }