Adds additional test cases for sapi::file::CleanPath and updates

the documentation.

No behaviour changes are introduced.

PiperOrigin-RevId: 721539154
Change-Id: I52a96055614518d169908f15a4c79f2cb6b5825b

Author: okunz

sandboxed_api/util/path.h

@@ -48,10 +48,15 @@ std::pair<absl::string_view, absl::string_view> SplitPath(
 // Collapses duplicate "/"s, resolve ".." and "." path elements, removes
 // trailing "/".
 //
-// NOTE: This respects relative vs. absolute paths, but does not
-// invoke any system calls in order to resolve relative paths to the actual
-// working directory. That is, this is purely a string manipulation, completely
-// independent of process state.
+// This is purely a string manipulation and does not invoke any system calls in
+// order to resolve relative paths to the actual working directory.
+//
+// For absolute paths, this is equivalent to the following:
+//   /path/to/./foo/../bar/../baz/ -> /path/to/bar/baz
+//
+// For relative paths, this is equivalent to the following:
+//   ./path/to/./foo/../bar/../baz/ -> path/to/bar/baz
+//   ../path/to/./foo/../bar/../baz/ -> ../path/to/bar/baz
 std::string CleanPath(absl::string_view path);
 
 }  // namespace sapi::file

sandboxed_api/util/path_test.cc

@@ -96,6 +96,12 @@ TEST(PathTest, CleanPath) {
   EXPECT_THAT(file::CleanPath("../../a/b/../c"), StrEq("../../a/c"));
   EXPECT_THAT(file::CleanPath("../../a/b/../c/../.."), StrEq("../.."));
   EXPECT_THAT(file::CleanPath("foo/../../../bar"), StrEq("../../bar"));
+  EXPECT_THAT(file::CleanPath("/path/to/./foo/../bar/../baz/"),
+              StrEq("/path/to/baz"));
+  EXPECT_THAT(file::CleanPath("./path/to/./foo/../bar/../baz/"),
+              StrEq("path/to/baz"));
+  EXPECT_THAT(file::CleanPath("../path/to/./foo/../bar/../baz/"),
+              StrEq("../path/to/baz"));
 }
 
 }  // namespace