Plugin templates enabled

This lets a plugin define templates to be loaded:

    $ rebar3 new
    ...
    proper (plugin): A basic PropEr suite for an OTP application
    ...
    $ rebar3 new help proper
    proper:
            plugin template (...)
            Description: A basic PropEr suite for an OTP application
            Variables:
                    name="suite" (...)
                    ...
    → rebar3 new proper fakesuite
    ===> Writing test/prop_fakesuite.erl

In this case, proper is a fake template file I've put by hand in
_build/default/plugins/rebar3_proper/priv/<somename>/, meaning it will
only work as far as it's called from the project's root.

The priority order of plugins is now .config > plugin > built-in, such
that someone could ensure plugins do not crush their own private
templates, but also that custom or plugin templates do overtake built-in
ones. It used to be Built-in > .config only.

Templates are searched for recursively in the priv/ directory of
plugins.

10 files changed, 116 insertions, 0 deletions

diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/.gitignore b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/.gitignore
new file mode 100644
index 0000000..a939dce
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/.gitignore
@@ -0,0 +1,19 @@
+.rebar3
+_*
+.eunit
+*.o
+*.beam
+*.plt
+*.swp
+*.swo
+.erlang.cookie
+ebin
+log
+erl_crash.dump
+.rebar
+_rel
+_deps
+_plugins
+_tdeps
+logs
+_build
\ No newline at end of file
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/module.erl.dtl b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/module.erl.dtl
new file mode 100644
index 0000000..9129961
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/module.erl.dtl
@@ -0,0 +1,2 @@
+-module({{name}}).
+
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/tpl.template b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/tpl.template
new file mode 100644
index 0000000..7fa4caf
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/priv/tpl.template
@@ -0,0 +1,7 @@
+{description, "A basic template"}.
+{variables, [
+    {name, "mod", "Name of the module"}
+]}.
+
+{dir, "test"}.
+{template, "module.erl.dtl", "src/{{name}}.erl"}.
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/rebar.config b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/rebar.config
new file mode 100644
index 0000000..f618f3e
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/rebar.config
@@ -0,0 +1,2 @@
+{erl_opts, [debug_info]}.
+{deps, []}.
\ No newline at end of file
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.app.src b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.app.src
new file mode 100644
index 0000000..6c6d811
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.app.src
@@ -0,0 +1,15 @@
+{application, 'tpl',
+ [{description, "A rebar plugin"},
+  {vsn, "0.1.0"},
+  {registered, []},
+  {applications,
+   [kernel,
+    stdlib
+   ]},
+  {env,[]},
+  {modules, []},
+
+  {contributors, []},
+  {licenses, []},
+  {links, []}
+ ]}.
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.erl b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.erl
new file mode 100644
index 0000000..529bcb8
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl.erl
@@ -0,0 +1,8 @@
+-module('tpl').
+
+-export([init/1]).
+
+-spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
+init(State) ->
+    {ok, State1} = 'tpl_prv':init(State),
+    {ok, State1}.
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl_prv.erl b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl_prv.erl
new file mode 100644
index 0000000..c68ffa3
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/_checkouts/tpl/src/tpl_prv.erl
@@ -0,0 +1,32 @@
+-module('tpl_prv').
+
+-export([init/1, do/1, format_error/1]).
+
+-define(PROVIDER, 'tpl').
+-define(DEPS, [app_discovery]).
+
+%% ===================================================================
+%% Public API
+%% ===================================================================
+-spec init(rebar_state:t()) -> {ok, rebar_state:t()}.
+init(State) ->
+    Provider = providers:create([
+            {name, ?PROVIDER},            % The 'user friendly' name of the task
+            {module, ?MODULE},            % The module implementation of the task
+            {bare, true},                 % The task can be run by the user, always true
+            {deps, ?DEPS},                % The list of dependencies
+            {example, "rebar3 tpl"}, % How to use the plugin
+            {opts, []},                   % list of options understood by the plugin
+            {short_desc, "A rebar plugin"},
+            {desc, "A rebar plugin"}
+    ]),
+    {ok, rebar_state:add_provider(State, Provider)}.
+
+
+-spec do(rebar_state:t()) -> {ok, rebar_state:t()} | {error, string()}.
+do(State) ->
+    {ok, State}.
+
+-spec format_error(any()) ->  iolist().
+format_error(Reason) ->
+    io_lib:format("~p", [Reason]).
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/rebar.config b/test/rebar_new_SUITE_data/plugin_tpl/rebar.config
new file mode 100644
index 0000000..74d1fc5
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/rebar.config
@@ -0,0 +1,3 @@
+{erl_opts, [debug_info]}.
+{deps, []}.
+{plugins, [tpl]}.
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.app.src b/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.app.src
new file mode 100644
index 0000000..8f18874
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.app.src
@@ -0,0 +1,15 @@
+{application, 'plugin_tpl',
+ [{description, "An OTP library"},
+  {vsn, "0.1.0"},
+  {registered, []},
+  {applications,
+   [kernel,
+    stdlib
+   ]},
+  {env,[]},
+  {modules, []},
+
+  {contributors, []},
+  {licenses, []},
+  {links, []}
+ ]}.
diff --git a/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.erl b/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.erl
new file mode 100644
index 0000000..406bd97
--- /dev/null
+++ b/test/rebar_new_SUITE_data/plugin_tpl/src/plugin_tpl.erl
@@ -0,0 +1,13 @@
+-module('plugin_tpl').
+
+%% API exports
+-export([]).
+
+%%====================================================================
+%% API functions
+%%====================================================================
+
+
+%%====================================================================
+%% Internal functions
+%%====================================================================