Certainly! Given the problem description for "Cubes Without Holes," we need to generate test cases that include the size of the cube (`n`), the number of marks (`h`), and the positions of these marks on specific planes. Below is a Python function that generates these test cases:

```python
import random

def generate_plane_mark(n):
    plane = random.choice(['xy', 'xz', 'yz'])
    if plane == 'xy':
        a = random.randint(1, n)
        b = random.randint(1, n)
    elif plane == 'xz':
        a = random.randint(1, n)
        b = random.randint(1, n)
    else:  # 'yz'
        a = random.randint(1, n)
        b = random.randint(1, n)
    return f"{plane} {a} {b}"

def tcgen():
    datasets = []
    while True:
        n = random.randint(1, 500)
        h = random.randint(1, 200)
        marks = [generate_plane_mark(n) for _ in range(h)]
        datasets.append((n, h, marks))
        if random.random() < 0.1:  # Randomly decide to end the input
            break
    datasets.append((0, 0, []))
    return datasets

# To output the generated test cases in the required format:
def print_test_cases(test_cases):
    for n, h, marks in test_cases:
        print(f"{n} {h}")
        for mark in marks:
            print(mark)

# Generate test cases
test_cases = tcgen()

# Print the test cases
print_test_cases(test_cases)
```

This code includes:
1. `generate_plane_mark(n)`: A helper function that generates a random mark based on the size of the cube `n`.
2. `tcgen()`: The main test case generator which creates multiple datasets until it randomly decides to end (with a 10% chance on each iteration).
3. `print_test_cases(test_cases)`: A helper function to print the generated test cases in the required format.

You can run this code to generate and print a series of test cases for the "Cubes Without Holes" problem. Each dataset will contain randomly generated values for `n`, `h`, and the marks on the cube.