From 7d455866853e915a1652513f2f14e2fcc67eafd6 Mon Sep 17 00:00:00 2001
From: Philip Harrison <philip@mailharrison.com>
Date: Mon, 29 Mar 2021 12:30:06 +0100
Subject: [PATCH] Go mod: Handle multi-line error messages

Changes the go mod updater error handling to fall back to matching the
whole string if no lines where matched against the regex.

Some errors where surfacing with an empty error message as we initially
match on the whole string but filter per line.
---
 .../go_modules/file_updater/go_mod_updater.rb | 24 ++++++++------
 .../file_updater/go_mod_updater_spec.rb       | 33 +++++++++++++++++++
 .../projects/unknown_revision_version/go.mod  |  7 ++++
 .../projects/unknown_revision_version/main.go |  8 +++++
 4 files changed, 62 insertions(+), 10 deletions(-)
 create mode 100644 go_modules/spec/fixtures/projects/unknown_revision_version/go.mod
 create mode 100644 go_modules/spec/fixtures/projects/unknown_revision_version/main.go

diff --git a/go_modules/lib/dependabot/go_modules/file_updater/go_mod_updater.rb b/go_modules/lib/dependabot/go_modules/file_updater/go_mod_updater.rb
index 5132c4735c5..cef9e481dce 100644
--- a/go_modules/lib/dependabot/go_modules/file_updater/go_mod_updater.rb
+++ b/go_modules/lib/dependabot/go_modules/file_updater/go_mod_updater.rb
@@ -269,22 +269,20 @@ def substitute_all(substitutions)
           write_go_mod(body)
         end
 
-        # rubocop:disable Metrics/AbcSize
-        # rubocop:disable Metrics/PerceivedComplexity
         def handle_subprocess_error(stderr)
           stderr = stderr.gsub(Dir.getwd, "")
 
           # Package version doesn't match the module major version
           error_regex = RESOLVABILITY_ERROR_REGEXES.find { |r| stderr =~ r }
           if error_regex
-            lines = stderr.lines.drop_while { |l| error_regex !~ l }
-            raise Dependabot::DependencyFileNotResolvable, lines.join
+            error_message = filter_error_message(message: stderr, regex: error_regex)
+            raise Dependabot::DependencyFileNotResolvable, error_message
           end
 
           repo_error_regex = REPO_RESOLVABILITY_ERROR_REGEXES.find { |r| stderr =~ r }
           if repo_error_regex
-            lines = stderr.lines.drop_while { |l| repo_error_regex !~ l }
-            ResolvabilityErrors.handle(lines.join, credentials: credentials)
+            error_message = filter_error_message(message: stderr, regex: repo_error_regex)
+            ResolvabilityErrors.handle(error_message, credentials: credentials)
           end
 
           path_regex = MODULE_PATH_MISMATCH_REGEXES.find { |r| stderr =~ r }
@@ -296,16 +294,22 @@ def handle_subprocess_error(stderr)
 
           out_of_disk_regex = OUT_OF_DISK_REGEXES.find { |r| stderr =~ r }
           if out_of_disk_regex
-            lines = stderr.lines.select { |l| out_of_disk_regex =~ l }
-            raise Dependabot::OutOfDisk.new, lines.join
+            error_message = filter_error_message(message: stderr, regex: out_of_disk_regex)
+            raise Dependabot::OutOfDisk.new, error_message
           end
 
           # We don't know what happened so we raise a generic error
           msg = stderr.lines.last(10).join.strip
           raise Dependabot::DependabotError, msg
         end
-        # rubocop:enable Metrics/PerceivedComplexity
-        # rubocop:enable Metrics/AbcSize
+
+        def filter_error_message(message:, regex:)
+          lines = message.lines.select { |l| regex =~ l }
+          return lines.join if lines.any?
+
+          # In case the regex is multi-line, match the whole string
+          message.match(regex).to_s
+        end
 
         def go_mod_path
           return "go.mod" if directory == "/"
diff --git a/go_modules/spec/dependabot/go_modules/file_updater/go_mod_updater_spec.rb b/go_modules/spec/dependabot/go_modules/file_updater/go_mod_updater_spec.rb
index 306f08c1f75..1491aeb396c 100644
--- a/go_modules/spec/dependabot/go_modules/file_updater/go_mod_updater_spec.rb
+++ b/go_modules/spec/dependabot/go_modules/file_updater/go_mod_updater_spec.rb
@@ -465,6 +465,39 @@
         end
       end
     end
+
+    context "for an unknown revision version" do
+      let(:project_name) { "unknown_revision_version" }
+      let(:dependency_name) do
+        "github.com/deislabs/oras"
+      end
+      let(:dependency_version) { "v0.10.0" }
+      let(:dependency_previous_version) { "v0.9.0" }
+      let(:requirements) do
+        [{
+          file: "go.mod",
+          requirement: dependency_version,
+          groups: [],
+          source: {
+            type: "default",
+            source: "github.com/deislabs/oras"
+          }
+        }]
+      end
+      let(:previous_requirements) { [] }
+
+      it "raises the correct error" do
+        error_class = Dependabot::DependencyFileNotResolvable
+        expect { updater.updated_go_sum_content }.
+          to raise_error(error_class) do |error|
+          expect(error.message).to include(
+            "go: github.com/deislabs/oras@v0.10.0 requires\n"\
+            "	github.com/docker/distribution@v0.0.0-00010101000000-000000000000: "\
+            "invalid version: unknown revision"
+          )
+        end
+      end
+    end
   end
 
   describe "#updated_go_sum_content" do
diff --git a/go_modules/spec/fixtures/projects/unknown_revision_version/go.mod b/go_modules/spec/fixtures/projects/unknown_revision_version/go.mod
new file mode 100644
index 00000000000..debfc31f10e
--- /dev/null
+++ b/go_modules/spec/fixtures/projects/unknown_revision_version/go.mod
@@ -0,0 +1,7 @@
+module github.com/dependabot/vgotest
+
+go 1.16
+
+require (
+  github.com/deislabs/oras v0.9.0
+)
diff --git a/go_modules/spec/fixtures/projects/unknown_revision_version/main.go b/go_modules/spec/fixtures/projects/unknown_revision_version/main.go
new file mode 100644
index 00000000000..e6ed617b7cf
--- /dev/null
+++ b/go_modules/spec/fixtures/projects/unknown_revision_version/main.go
@@ -0,0 +1,8 @@
+package main
+
+import (
+	_ "github.com/deislabs/oras"
+)
+
+func main() {
+}