test: less ambiguous error if bitcoind is missing

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.

test/functional/test_framework/test_framework.py

@@ -545,18 +545,23 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
                 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]
+        bin_dirs = []
-        # Fail test if any of the needed release binaries is missing
+        for v in versions:
-        bins_missing = False
+            bin_dir = bin_dir_from_version(v)
-        for bin_path in (argv[0] for bin_dir in bin_dirs
+
-                                 for binaries in (self.get_binaries(bin_dir),)
+            # Fail test if any of the needed release binaries is missing
-                                 for argv in (binaries.node_argv(), binaries.rpc_argv())):
+            for bin_path in (argv[0] for binaries in (self.get_binaries(bin_dir),)
-            if shutil.which(bin_path) is None:
+                                     for argv in (binaries.node_argv(), binaries.rpc_argv())):
-                self.log.error(f"Binary not found: {bin_path}")
+
-                bins_missing = True
+                if shutil.which(bin_path) is None:
-        if bins_missing:
+                    self.log.error(f"Binary not found: {bin_path}")
-            raise AssertionError("At least one release binary is missing. "
+                    if v is None:
-                                 "Previous releases binaries can be downloaded via `test/get_previous_releases.py`.")
+                        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)