Sure, I can write a test case generator for the "Cleaning Robot" problem. Here's a Python function that generates random test cases:

```python
import random

def generate_room():
    return random.choice(['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I'])

def generate_test_case():
    n = random.randint(1, 15)
    
    rooms = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I']
    
    s = generate_room()
    t = generate_room()
    b = generate_room()
    
    # Ensure s, t, and b are distinct
    while t == s or t == b:
        t = generate_room()
    while b == s or b == t:
        b = generate_room()
    
    return n, s, t, b

def generate_multiple_test_cases(num_cases):
    test_cases = []
    
    for _ in range(num_cases):
        test_cases.append(generate_test_case())
    
    # Add terminating case
    test_cases.append((0,))
    
    return test_cases

def format_test_cases(test_cases):
    formatted_cases = []
    
    for case in test_cases:
        if case[0] == 0:
            formatted_cases.append("0")
        else:
            formatted_cases.append(f"{case[0]}\n{case[1]} {case[2]} {case[3]}")
    
    return "\n".join(formatted_cases)

# Example usage
random.seed(42)  # Set a seed for reproducibility
test_cases = generate_multiple_test_cases(10)
formatted_test_cases = format_test_cases(test_cases)
print(formatted_test_cases)
```

This script generates a number of random test cases for the "Cleaning Robot" problem, ensuring that the start room (`s`), the battery room (`t`), and the junk room (`b`) are distinct. It then formats these test cases into a string that can be used as input for a program solving the problem.

You can adjust the `num_cases` parameter in the `generate_multiple_test_cases` function call to generate as many test cases as you need. The example usage at the end demonstrates generating and printing 10 test cases.