test: fix TestShell initialization and reset()

test/functional/test-shell.md

@@ -24,13 +24,16 @@ user inputs. Such environments include the Python3 command line interpreter or
 
 ## 2. Importing `TestShell` from the Bitcoin Core repository
 
-We can import the `TestShell` by adding the path of the Bitcoin Core
+We can import the `TestShell` by adding the path of the configured Bitcoin Core
 `test_framework` module to the beginning of the PATH variable, and then
-importing the `TestShell` class from the `test_shell` sub-package.
+importing the `TestShell` class from the `test_shell` sub-package. Since
+the build system creates a copy of the `test_framework` module into a new `build/`
+directory along with the required configuration file, the path to the build copy
+must be used.
 
 ```
 >>> import sys
->>> sys.path.insert(0, "/path/to/bitcoin/test/functional")
+>>> sys.path.insert(0, "/path/to/bitcoin/build/test/functional")
 >>> from test_framework.test_shell import TestShell
 ```
 

test/functional/test_framework/test_shell.py

@@ -7,6 +7,14 @@
 from test_framework.test_framework import BitcoinTestFramework
 
 
+# BitcoinTestFramework instances are supposed to be constructed with the path
+# of the calling test in order to find shared data like configuration and the
+# cache. Since TestShell is meant for interactive use, there is no concrete
+# test; passing a dummy name is fine though, as only the containing directory
+# is relevant for successful initialization.
+tests_directory = pathlib.Path(__file__).absolute().parent.parent
+dummy_testshell_file = tests_directory / "testshell_dummy.py"
+
 class TestShell:
     """Wrapper Class for BitcoinTestFramework.
 
@@ -61,21 +69,15 @@ def reset(self):
                 print("Shutdown TestShell before resetting!")
             else:
                 self.num_nodes = None
-                super().__init__()
+                super().__init__(dummy_testshell_file)
 
     instance = None
 
     def __new__(cls):
         # This implementation enforces singleton pattern, and will return the
         # previously initialized instance if available
         if not TestShell.instance:
-            # BitcoinTestFramework instances are supposed to be constructed with the path
-            # of the calling test in order to find shared data like configuration and the
-            # cache. Since TestShell is meant for interactive use, there is no concrete
-            # test; passing a dummy name is fine though, as only the containing directory
-            # is relevant for successful initialization.
-            tests_directory = pathlib.Path(__file__).resolve().parent.parent
-            TestShell.instance = TestShell.__TestShell(tests_directory / "testshell_dummy.py")
+            TestShell.instance = TestShell.__TestShell(dummy_testshell_file)
             TestShell.instance.running = False
         return TestShell.instance