Merge pull request #10306 from hercules-ci/baseNameOf

Test and document `builtins.baseNameOf`, improve internal `baseNameOf()`

tests/functional/lang/eval-okay-baseNameOf.exp

@@ -0,0 +1 @@
+"ok"

tests/functional/lang/eval-okay-baseNameOf.nix

@@ -0,0 +1,32 @@
+assert baseNameOf "" == "";
+assert baseNameOf "." == ".";
+assert baseNameOf ".." == "..";
+assert baseNameOf "a" == "a";
+assert baseNameOf "a." == "a.";
+assert baseNameOf "a.." == "a..";
+assert baseNameOf "a.b" == "a.b";
+assert baseNameOf "a.b." == "a.b.";
+assert baseNameOf "a.b.." == "a.b..";
+assert baseNameOf "a/" == "a";
+assert baseNameOf "a/." == ".";
+assert baseNameOf "a/.." == "..";
+assert baseNameOf "a/b" == "b";
+assert baseNameOf "a/b." == "b.";
+assert baseNameOf "a/b.." == "b..";
+assert baseNameOf "a/b/c" == "c";
+assert baseNameOf "a/b/c." == "c.";
+assert baseNameOf "a/b/c.." == "c..";
+assert baseNameOf "a/b/c/d" == "d";
+assert baseNameOf "a/b/c/d." == "d.";
+assert baseNameOf "a\\b" == "a\\b";
+assert baseNameOf "C:a" == "C:a";
+assert baseNameOf "a//b" == "b";
+
+# It's been like this for close to a decade. We ought to commit to it.
+# https://github.com/NixOS/nix/pull/582#issuecomment-121014450
+assert baseNameOf "a//" == "";
+
+assert baseNameOf ./foo == "foo";
+assert baseNameOf ./foo/bar == "bar";
+
+"ok"

tests/unit/libutil/tests.cc

@@ -151,6 +151,16 @@ namespace nix {
         ASSERT_EQ(p1, "dir");
     }
 
+    TEST(baseNameOf, trailingSlashes) {
+        auto p1 = baseNameOf("/dir//");
+        ASSERT_EQ(p1, "dir");
+    }
+
+    TEST(baseNameOf, absoluteNothingSlashNothing) {
+        auto p1 = baseNameOf("//");
+        ASSERT_EQ(p1, "");
+    }
+
     /* ----------------------------------------------------------------------------
      * isInDir
      * --------------------------------------------------------------------------*/