Merge bitcoin/bitcoin#32921: test: less ambiguous error if bitcoind is missing

83bb414 test: less ambiguous error if bitcoind is missing (Sjors Provoost)

Pull request description:

  Before this change, when a functional test is run without building the source,  the error message suggested that previous release binaries were missing.

  When no previous release version is set, make the error message more specifically about bitcoind.

  To test, try this before and after:

  ```sh
  git clean -dfx
  cmake -B build
  build/test/functional/mining_basic.py
  cmake --build build
  build/test/functional/mining_basic.py
  build/test/functional/wallet_backwards_compatibility.py
  test/get_previous_releases.py
  build/test/functional/wallet_backwards_compatibility.py
  ```

ACKs for top commit:
  achow101:
    ACK 83bb414
  janb84:
    ACK 83bb414
  w0xlt:
    ACK bitcoin/bitcoin@83bb414

Tree-SHA512: c6df65019de99d6c214951cf70944c4ddca9b635c5ab60ac2c47e4589478e9c65d5e079c394ace9b470a7eaeea3c9cf68b7246dd413e802c4a1e071913a7fc32

Author: achow101

test/functional/test_framework/test_framework.py

@@ -545,18 +545,23 @@ def bin_dir_from_version(version):
                 extra_args[i] = extra_args[i] + ["-whitelist=noban,in,out@127.0.0.1"]
         if versions is None:
             versions = [None] * num_nodes
-        bin_dirs = [bin_dir_from_version(v) for v in versions]
-        # Fail test if any of the needed release binaries is missing
-        bins_missing = False
-        for bin_path in (argv[0] for bin_dir in bin_dirs
-                                 for binaries in (self.get_binaries(bin_dir),)
-                                 for argv in (binaries.node_argv(), binaries.rpc_argv())):
-            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`.")
+        bin_dirs = []
+        for v in versions:
+            bin_dir = bin_dir_from_version(v)
+
+            # Fail test if any of the needed release binaries is missing
+            for bin_path in (argv[0] for binaries in (self.get_binaries(bin_dir),)
+                                     for argv in (binaries.node_argv(), binaries.rpc_argv())):
+
+                if shutil.which(bin_path) is None:
+                    self.log.error(f"Binary not found: {bin_path}")
+                    if v is None:
+                        raise AssertionError("At least one binary is missing, did you compile?")
+                    raise AssertionError("At least one release binary is missing. "
+                                         "Previous releases binaries can be downloaded via `test/get_previous_releases.py`.")
+
+            bin_dirs.append(bin_dir)
+
         assert_equal(len(extra_confs), num_nodes)
         assert_equal(len(extra_args), num_nodes)
         assert_equal(len(versions), num_nodes)