Sure, here is a test case generator for the Goldbach's Conjecture problem. The generator will produce multiple even numbers in the specified range and will stop when a 0 is generated to indicate the end of the input.

First, let's implement the test case generator function:

```python
import random

def tcgen():
    def is_prime(n):
        if n <= 1:
            return False
        if n <= 3:
            return True
        if n % 2 == 0 or n % 3 == 0:
            return False
        i = 5
        while i * i <= n:
            if n % i == 0 or n % (i + 2) == 0:
                return False
            i += 6
        return True

    even_numbers = [random.choice(range(4, 215, 2)) for _ in range(random.randint(1, 10))]
    even_numbers.append(0)

    return even_numbers

# Example usage:
print(tcgen())
```

This code will generate a list of even numbers between 4 and 214 and will append a 0 at the end to indicate the end of the input sequence. The number of even numbers generated (excluding the terminating 0) will be between 1 and 10, which you can adjust as needed.

Here is a brief explanation of the function:

1. `is_prime(n)`: A helper function to determine if a number is prime.
2. `even_numbers`: A list comprehension generates a random list of even numbers within the range [4, 214]. The range is stepped by 2 to ensure only even numbers are included.
3. Append `0` to the list to indicate the end of the input.

The output will be a list of even numbers followed by a 0. Each even number in the list can then be tested for the Goldbach pairs in your main function.