Merge bitcoin/bitcoin#31462: test: raise explicit error if any of the needed release binaries is missing

1ea7e45 test: raise explicit error if any of the needed release binaries is missing (Sebastian Falbesoner)

Pull request description:

  If the `releases` directory exists, but still only a subset of the necessary previous release binaries are available, the test fails by throwing an exception (sometimes leading to follow-up exceptions like `AssertionError: [node 0] Error: no RPC connection`) and printing out a stack trace, which can be confusing and at a first glance suggests that the node crashed or some alike.
  Improve this by checking and printing out *all* of the missing release binaries and failing with an explicit error in this case. Also add an info on how to download previous releases binaries. Noticed while testing #30328.

  Can be tested by e.g.

  ```
  $ rm -rf ./releases
  $ ./test/get_previous_releases.py -b
  $ rm -rf ./releases/v28.0/
  $ ./build/test/functional/wallet_migration.py
  ```

  master:
  <details>
  <summary>Long test fail output</summary>

  ```
  ...
  2024-12-10T18:48:54.067000Z TestFramework (ERROR): Assertion failed
  Traceback (most recent call last):
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 590, in start_nodes
      node.start(extra_args[i], *args, **kwargs)
    File "/home/thestack/bitcoin/test/functional/test_framework/test_node.py", line 257, in start
      self.process = subprocess.Popen(self.args + extra_args, env=subp_env, stdout=stdout, stderr=stderr, cwd=cwd, **kwargs)
    File "/usr/lib/python3.10/subprocess.py", line 971, in __init__
      self._execute_child(args, executable, preexec_fn, close_fds,
    File "/usr/lib/python3.10/subprocess.py", line 1863, in _execute_child
      raise child_exception_type(errno_num, err_msg, err_filename)
  FileNotFoundError: [Errno 2] No such file or directory: '/home/thestack/bitcoin/releases/v28.0/bin/bitcoind'

  During handling of the above exception, another exception occurred:

  Traceback (most recent call last):
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 131, in main
      self.setup()
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 315, in setup
      self.setup_network()
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 409, in setup_network
      self.setup_nodes()
    File "/home/thestack/bitcoin/./build/test/functional/wallet_migration.py", line 54, in setup_nodes
      self.start_nodes()
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 595, in start_nodes
      self.stop_nodes()
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 610, in stop_nodes
      node.stop_node(wait=wait, wait_until_stopped=False)
    File "/home/thestack/bitcoin/test/functional/test_framework/test_node.py", line 396, in stop_node
      self.stop(wait=wait)
    File "/home/thestack/bitcoin/test/functional/test_framework/test_node.py", line 215, in __getattr__
      assert self.rpc_connected and self.rpc is not None, self._node_msg("Error: no RPC connection")
  AssertionError: [node 0] Error: no RPC connection
  2024-12-10T18:48:54.118000Z TestFramework (INFO): Stopping nodes
  Traceback (most recent call last):
    File "/home/thestack/bitcoin/./build/test/functional/wallet_migration.py", line 1097, in <module>
      WalletMigrationTest(__file__).main()
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 159, in main
      exit_code = self.shutdown()
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 331, in shutdown
      self.stop_nodes()
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 610, in stop_nodes
      node.stop_node(wait=wait, wait_until_stopped=False)
    File "/home/thestack/bitcoin/test/functional/test_framework/test_node.py", line 396, in stop_node
      self.stop(wait=wait)
    File "/home/thestack/bitcoin/test/functional/test_framework/test_node.py", line 215, in __getattr__
      assert self.rpc_connected and self.rpc is not None, self._node_msg("Error: no RPC connection")
  AssertionError: [node 0] Error: no RPC connection
  [node 0] Cleaning up leftover process
  ...
  ```
  </details>

  PR:
  ```
  ...
  2025-01-01T20:26:27.999000Z TestFramework (INFO): PRNG seed is: 4570383538468804512
  2025-01-01T20:26:28.000000Z TestFramework (INFO): Initializing test directory /tmp/bitcoin_func_test_lz66_zcu
  2025-01-01T20:26:28.003000Z TestFramework (ERROR): Binary not found: /home/thestack/bitcoin/releases/v28.0/bin/bitcoind
  2025-01-01T20:26:28.003000Z TestFramework (ERROR): Binary not found: /home/thestack/bitcoin/releases/v28.0/bin/bitcoin-cli
  2025-01-01T20:26:28.003000Z TestFramework (INFO): Previous releases binaries can be downloaded via `test/get_previous_releases.py -b`.
  2025-01-01T20:26:28.003000Z TestFramework (ERROR): Assertion failed
  Traceback (most recent call last):
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 131, in main
      self.setup()
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 315, in setup
      self.setup_network()
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 409, in setup_network
      self.setup_nodes()
    File "/home/thestack/bitcoin/./build/test/functional/wallet_migration.py", line 50, in setup_nodes
      self.add_nodes(self.num_nodes, versions=[
    File "/home/thestack/bitcoin/test/functional/test_framework/test_framework.py", line 537, in add_nodes
      raise AssertionError("At least one release binary is missing")
  AssertionError: At least one release binary is missing
  2025-01-01T20:26:28.061000Z TestFramework (INFO): Stopping nodes
  ...
  ```

ACKs for top commit:
  fjahr:
    re-ACK 1ea7e45
  kevkevinpal:
    ACK [1ea7e45](bitcoin/bitcoin@1ea7e45)
  maflcko:
    lgtm ACK 1ea7e45
  achow101:
    ACK 1ea7e45
  pablomartin4btc:
    tACK 1ea7e45

Tree-SHA512: b621c3ce044ca8fc8715a4f4b1f96a8592a470c319a64444cced9ba692d315cfd4885a066679bf377b19136fa3530d9cff6f18894a45aa9c716d39b12719baa0

Author: achow101

test/functional/test_framework/test_framework.py

@@ -526,6 +526,15 @@ def get_bin_from_version(version, bin_name, bin_default):
             binary = [get_bin_from_version(v, 'bitcoind', self.options.bitcoind) for v in versions]
         if binary_cli is None:
             binary_cli = [get_bin_from_version(v, 'bitcoin-cli', self.options.bitcoincli) for v in versions]
+        # Fail test if any of the needed release binaries is missing
+        bins_missing = False
+        for bin_path in binary + binary_cli:
+            if shutil.which(bin_path) is None:
+                self.log.error(f"Binary not found: {bin_path}")
+                bins_missing = True
+        if bins_missing:
+            raise AssertionError("At least one release binary is missing. "
+                                 "Previous releases binaries can be downloaded via `test/get_previous_releases.py -b`.")
         assert_equal(len(extra_confs), num_nodes)
         assert_equal(len(extra_args), num_nodes)
         assert_equal(len(versions), num_nodes)