Fix Plugin path handling (again!)

The path reloading of plugins had been fixed properly, but the problem
is that the paths it was using to re-load only considered the current
compile step, rather than the overall state of plugins. As such, the
reloaded paths after plugin compilation only reloaded the *latest*
plugin and not the other ones.

This fix forces the addition of all built plugin paths to the code paths
after a plugin compile job is run. This ensures that the path is clean
for initial plugin deps (only add those that are required), and is
re-made total after the fact (add all the plugins possible).

This commit also includes a system tests suite that can be run
optionally; the problem with this plugin mechanism was impossible to
find through mocked dependencies, and a working counterexample was
provided to us. The systest suite can be run against real projects
without conflict to make sure no regressions are hit.

1 files changed, 23 insertions, 0 deletions

diff --git a/systest/all_SUITE_data/resource_plugins/rebar.config b/systest/all_SUITE_data/resource_plugins/rebar.config
new file mode 100644
index 0000000..7baec1f
--- /dev/null
+++ b/systest/all_SUITE_data/resource_plugins/rebar.config
@@ -0,0 +1,23 @@
+%% Sample provided by @tothlac
+{plugins, [
+    {rebar_tidy_deps, ".*", {git, "https://github.com/ferd/rebar3-tidy-deps-plugin.git"}},
+    {rebar_alias, {git, "https://github.com/tsloughter/rebar_alias.git"}},
+    rebar3_appup_plugin
+]}.
+
+{deps, [
+    {hackney, {git, "https://github.com/benoitc/hackney.git", {tag, "1.10.1"}}}
+ ]}.
+
+
+%% Make work despite compat issues with strings and warnings
+{overrides, [
+  {override, rebar3_appup_plugin, [
+    {erl_opts, [
+        {platform_define, "^19", brutal_purge_fixed},
+        {platform_define, "^2", brutal_purge_fixed},
+        %% warnings_as_errors,
+        debug_info
+    ]}
+  ]}
+]}.