Merge #7011

7011: Do not prepend ENV vars for sys_exec calls, but use env param of Open3.popen3 r=deivid-rodriguez a=janpio

### What was the end-user problem that led to this PR?

Several tests were failing on Windows because of the same problem:

### What was your diagnosis of the problem?

On macOS and Linux you can prepend `ENV_VAR=value` in front of a command to set an environment variable for just this command execution. 

On Windows this construct doesn't exit and such a command fails.

### What is your fix for the problem, implemented in this PR?

`Open3.popen3`, the method used to executed the command in `sys_exec`, also has an optional `env` parameter which you can use to supply a hash of environment variables. Instead of prepending on the command itself, the code now uses that parameter for the env variables. (Suggested by @deivid-rodriguez in https://github.com/bundler/bundler/issues/6886#issuecomment-452010623).

### Why did you choose this fix out of the possible options?

The parameter of `Open3.popen3` perfectly matches our use case.

---

Fixes 35 failing tests on Windows.

closes #6886

Co-authored-by: Jan Piotrowski <piotrowski+git@gmail.com>

3 files changed, 8 insertions, 8 deletions

diff --git a/spec/commands/binstubs_spec.rb b/spec/commands/binstubs_spec.rb
index b958677876..9126b29592 100644
--- a/spec/commands/binstubs_spec.rb
+++ b/spec/commands/binstubs_spec.rb
@@ -133,7 +133,7 @@ RSpec.describe "bundle binstubs <gem>" do
 
       context "when BUNDLER_VERSION is set" do
         it "runs the correct version of bundler" do
-          sys_exec "BUNDLER_VERSION='999.999.999' #{bundled_app("bin/bundle")} install"
+          sys_exec "#{bundled_app("bin/bundle")} install", "BUNDLER_VERSION" => "999.999.999"
           expect(exitstatus).to eq(42) if exitstatus
           expect(last_command.stderr).to include("Activating bundler (999.999.999) failed:").
             and include("To install the version of bundler this project requires, run `gem install bundler -v '999.999.999'`")
diff --git a/spec/commands/newgem_spec.rb b/spec/commands/newgem_spec.rb
index c7cc5e594a..0d1058ad11 100644
--- a/spec/commands/newgem_spec.rb
+++ b/spec/commands/newgem_spec.rb
@@ -162,7 +162,7 @@ RSpec.describe "bundle gem" do
       load_paths = [lib, spec]
       load_path_str = "-I#{load_paths.join(File::PATH_SEPARATOR)}"
 
-      sys_exec "PATH=\"\" #{Gem.ruby} #{load_path_str} #{bindir.join("bundle")} gem #{gem_name}"
+      sys_exec "#{Gem.ruby} #{load_path_str} #{bindir.join("bundle")} gem #{gem_name}", "PATH" => ""
     end
 
     it "creates the gem without the need for git" do
diff --git a/spec/support/helpers.rb b/spec/support/helpers.rb
index 9be5955ac3..4eb98645a5 100644
--- a/spec/support/helpers.rb
+++ b/spec/support/helpers.rb
@@ -131,8 +131,6 @@ module Spec
       load_path << spec
       load_path_str = "-I#{load_path.join(File::PATH_SEPARATOR)}"
 
-      env = env.map {|k, v| "#{k}='#{v}'" }.join(" ")
-
       args = options.map do |k, v|
         case v
         when nil
@@ -146,8 +144,8 @@ module Spec
         end
       end.join
 
-      cmd = "#{env} #{sudo} #{Gem.ruby} #{load_path_str} #{requires_str} #{bundle_bin} #{cmd}#{args}"
-      sys_exec(cmd) {|i, o, thr| yield i, o, thr if block_given? }
+      cmd = "#{sudo} #{Gem.ruby} #{load_path_str} #{requires_str} #{bundle_bin} #{cmd}#{args}"
+      sys_exec(cmd, env) {|i, o, thr| yield i, o, thr if block_given? }
     end
     bang :bundle
 
@@ -216,10 +214,12 @@ module Spec
       "#{Gem.ruby} -S #{ENV["GEM_PATH"]}/bin/rake"
     end
 
-    def sys_exec(cmd)
+    def sys_exec(cmd, env = {})
       command_execution = CommandExecution.new(cmd.to_s, Dir.pwd)
 
-      Open3.popen3(cmd.to_s) do |stdin, stdout, stderr, wait_thr|
+      env = env.map {|k, v| [k.to_s, v.to_s] }.to_h # convert env keys and values to string
+
+      Open3.popen3(env, cmd.to_s) do |stdin, stdout, stderr, wait_thr|
         yield stdin, stdout, wait_thr if block_given?
         stdin.close