use absolute paths in example to match docs

docs/source/usage/graders/examples/file_io.py

@@ -8,20 +8,24 @@
 student_submission = Path(sys.argv[2])
 
 # input file is in the same directory as our grader (this file)
-INPUT_FILE = Path(__file__).parent / "input.txt"
+# make sure to use the absolute path
+INPUT_FILE = (Path(__file__).parent / "input.txt").resolve()
+
 # output file is in the same directory as the student submission
 # This way we can avoid multiple submissions trying to write to
 # the same file.
-OUTPUT_FILE = student_submission.parent / "output.txt"
+# Again, making sure to use the absolute path
+OUTPUT_FILE = (student_submission.parent / "output.txt").resolve()
 
 
 command = [
     sys.executable,
     submission,
     # give read permissions to the input
+    # making sure to use the absolute path to the file
     "--read",
     INPUT_FILE,
-    # and allow them to read/write to output
+    # and allow them to read/write to the output file
     "--write",
     OUTPUT_FILE,
     # and then pass the arguments to the student submission
@@ -37,7 +41,11 @@
     check=False,
 )
 
-if resp.returncode == 0:
-    print(f"Score: {100 if OUTPUT_FILE.read_text() == INPUT_FILE.read_text() else 0}%")
-else:
+if (
+    resp.returncode != 0
+    or not OUTPUT_FILE.exists()
+    or OUTPUT_FILE.read_text() != INPUT_FILE.read_text()
+):
     print("Score: 0%")
+else:
+    print("Score: 100%")