test(erlang): add shared test helper and DRY app setup

binding/erlang/test/ip2region_sup_test.erl

@@ -3,22 +3,6 @@
 -include("ip2region.hrl").
 
 pools_started_test() ->
-    try application:stop(ip2region) catch _:_ -> ok end,
-    try application:unload(ip2region) catch _:_ -> ok end,
-    ok = application:load(ip2region),
-    %% NOTE: rebar3 compiles tests under _build/test/lib/ip2region via a
-    %% symlink back to the source tree, so ?FILE resolves to the original
-    %% binding/erlang/test/... path. If rebar3 is configured to copy
-    %% instead of symlink, this path traversal must be adjusted.
-    TestDir = filename:dirname(?FILE),
-    ErlangDir = filename:dirname(TestDir),
-    BindingDir = filename:dirname(ErlangDir),
-    RepoRoot = filename:dirname(BindingDir),
-    V6File = filename:join([RepoRoot, "data", "ip2region_v6.xdb"]),
-    ok = application:set_env(ip2region, db, [
-        {ipv4, "ip2region.xdb"},
-        {ipv6, V6File}
-    ]),
-    {ok, _} = application:ensure_all_started(ip2region),
+    {ok, _} = ip2region_test_util:start_app(),
     ?assert(is_pid(whereis(?IP2REGION_POOL_V4))),
     ?assert(is_pid(whereis(?IP2REGION_POOL_V6))).

binding/erlang/test/ip2region_test_util.erl

@@ -0,0 +1,51 @@
+-module(ip2region_test_util).
+
+-export([
+    repo_root/0,
+    v6_xdb_path/0,
+    default_db_config/0,
+    reset_app/0,
+    load_app/0,
+    set_db_config/1,
+    start_app/0,
+    start_app/1,
+    stop_app/0
+]).
+
+repo_root() ->
+    TestDir = filename:dirname(?FILE),
+    ErlangDir = filename:dirname(TestDir),
+    BindingDir = filename:dirname(ErlangDir),
+    filename:dirname(BindingDir).
+
+v6_xdb_path() ->
+    filename:join([repo_root(), "data", "ip2region_v6.xdb"]).
+
+default_db_config() ->
+    [
+        {ipv4, "ip2region.xdb"},
+        {ipv6, v6_xdb_path()}
+    ].
+
+reset_app() ->
+    try application:stop(ip2region) catch _:_ -> ok end,
+    try application:unload(ip2region) catch _:_ -> ok end,
+    ok.
+
+load_app() ->
+    ok = application:load(ip2region).
+
+set_db_config(Config) ->
+    ok = application:set_env(ip2region, db, Config).
+
+start_app() ->
+    start_app(default_db_config()).
+
+start_app(Config) ->
+    reset_app(),
+    load_app(),
+    set_db_config(Config),
+    application:ensure_all_started(ip2region).
+
+stop_app() ->
+    application:stop(ip2region).