Merge pull request #2830 from dependabot/fatih/silently-fail-go-mod-tidy

go_modules: don't raise error for go mod tidy

go_modules/lib/dependabot/go_modules/file_updater/go_mod_updater.rb

@@ -118,9 +118,15 @@ def update_files # rubocop:disable Metrics/AbcSize
         def run_go_mod_tidy
           return unless tidy?
 
+          # NOTE(arslan): use `go mod tidy -e` once Go 1.16 is out:
+          # https://github.com/golang/go/commit/3aa09489ab3aa13a3ac78b1ff012b148ffffe367
           command = "go mod tidy"
-          _, stderr, status = Open3.capture3(ENVIRONMENT, command)
-          handle_subprocess_error(stderr) unless status.success?
+
+          # we explicitly don't raise an error for 'go mod tidy' and silently
+          # continue here. `go mod tidy` shouldn't block updating versions
+          # because there are some edge cases where it's OK to fail (such as
+          # generated files not available yet to us).
+          Open3.capture3(ENVIRONMENT, command)
         end
 
         def run_go_vendor

go_modules/spec/dependabot/go_modules/file_updater/go_mod_updater_spec.rb

@@ -225,12 +225,16 @@
             # OpenAPIV2 has been renamed to openapiv2 in this version
             let(:dependency_version) { "v0.5.1" }
 
-            it "raises a DependencyFileNotResolvable error" do
-              error_class = Dependabot::DependencyFileNotResolvable
+            # NOTE: We explitly don't want to raise a resolvability error from go mod tidy
+            it "does not raises a DependencyFileNotResolvable error" do
               expect { updater.updated_go_sum_content }.
-                to raise_error(error_class) do |error|
-                expect(error.message).to include("googleapis/gnostic/OpenAPIv2")
-              end
+                to_not raise_error(Dependabot::DependencyFileNotResolvable)
+            end
+
+            it "updates the go.mod" do
+              expect(updater.updated_go_mod_content).to include(
+                %(github.com/googleapis/gnostic v0.5.1 // indirect\n)
+              )
             end
           end
         end