add idempotence check to rebar_file_utils symlink functions

test/rebar_file_utils_SUITE.erl

@@ -354,6 +354,15 @@ symlink_existing_dir(Config) ->
 
     ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
 
+    %% `Target' should be a symlink, and `Source'
+    %% should exist
+    ?assert(ec_file:is_dir(Target)),
+    ?assert(ec_file:is_symlink(Target)),
+    ?assert(ec_file:is_dir(Source)),
+
+    %% repeat to check for idempotence
+    ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
+
     %% `Target' should be a symlink, and `Source'
     %% should exist
     ?assert(ec_file:is_dir(Target)),
@@ -373,6 +382,15 @@ preserve_existing_symlink(Config) ->
 
     ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
 
+    %% `Target' should be a symlink, and `Source'
+    %% should exist
+    ?assert(ec_file:is_dir(Target)),
+    ?assert(ec_file:is_symlink(Target)),
+    ?assert(ec_file:is_dir(Source)),
+
+    %% repeat to check for idempotence
+    ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
+
     %% `Target' should be a symlink, and `Source'
     %% should exist
     ?assert(ec_file:is_dir(Target)),
@@ -388,6 +406,15 @@ create_missing_dir(Config) ->
 
     ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
 
+    %% `Target' should be a directory not a symlink, and `Source'
+    %% should not exist
+    ?assert(ec_file:is_dir(Target)),
+    ?assert(not ec_file:is_symlink(Target)),
+    ?assert(not ec_file:is_dir(Source)),
+
+    %% repeat to check for idempotence
+    ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
+
     %% `Target' should be a directory not a symlink, and `Source'
     %% should not exist
     ?assert(ec_file:is_dir(Target)),
@@ -405,6 +432,15 @@ preserve_existing_dir(Config) ->
 
     ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
 
+    %% `Target' should be a directory, and `Source'
+    %% should not exist
+    ?assert(ec_file:is_dir(Target)),
+    ?assert(not ec_file:is_symlink(Target)),
+    ?assert(not ec_file:is_dir(Source)),
+
+    %% repeat to check for idempotence
+    ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
+
     %% `Target' should be a directory, and `Source'
     %% should not exist
     ?assert(ec_file:is_dir(Target)),
@@ -431,6 +467,15 @@ delete_symlink_and_create_dir(Config) ->
 
     ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
 
+    %% `Target' should be a directory not a symlink, and `Source'
+    %% should not exist
+    ?assert(not ec_file:is_symlink(Target)),
+    ?assert(ec_file:is_dir(Target)),
+    ?assert(not ec_file:is_dir(Source)),
+
+    %% repeat to check for idempotence
+    ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
+
     %% `Target' should be a directory not a symlink, and `Source'
     %% should not exist
     ?assert(not ec_file:is_symlink(Target)),
@@ -453,6 +498,15 @@ delete_dir_and_create_symlink(Config) ->
 
     ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
 
+    %% `Target' should be a symlink not a directory, and `Source'
+    %% should exist
+    ?assert(ec_file:is_dir(Target)),
+    ?assert(ec_file:is_symlink(Target)),
+    ?assert(ec_file:is_dir(Source)),
+
+    %% repeat to check for idempotence
+    ok = rebar_file_utils:symlink_or_create_dir(Source, Target),
+
     %% `Target' should be a symlink not a directory, and `Source'
     %% should exist
     ?assert(ec_file:is_dir(Target)),