Add unit tests for get_cwd() variable substitution (#262)

* Initial plan

* Expand get_cwd() to resolve all file-related VS Code variables

Co-authored-by: edvilme <5952839+edvilme@users.noreply.github.com>

* Add unit tests for get_cwd() variable substitutions

Co-authored-by: edvilme <5952839+edvilme@users.noreply.github.com>

* Inline LSP mock setup into test_get_cwd.py and remove conftest.py

Co-authored-by: edvilme <5952839+edvilme@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: edvilme <5952839+edvilme@users.noreply.github.com>

Author: Copilot

bundled/tool/lsp_server.py

@@ -292,17 +292,57 @@ def on_shutdown(_params: Optional[Any] = None) -> None:
 def get_cwd(settings: dict, document: Optional[workspace.Document]) -> str:
     """Returns the working directory for running the tool.
 
-    Resolves ``${fileDirname}`` to the directory of the current document.
-    If no document is available, falls back to the workspace root.
-
-    Examples of supported patterns: ``${fileDirname}``, ``${fileDirname}/subdir``.
+    Resolves the following VS Code file-related variable substitutions when
+    a document is available:
+
+    - ``${file}`` – absolute path of the current document.
+    - ``${fileBasename}`` – file name with extension (e.g. ``foo.py``).
+    - ``${fileBasenameNoExtension}`` – file name without extension (e.g. ``foo``).
+    - ``${fileExtname}`` – file extension including the dot (e.g. ``.py``).
+    - ``${fileDirname}`` – directory containing the current document.
+    - ``${fileDirnameBasename}`` – name of the directory containing the document.
+    - ``${relativeFile}`` – document path relative to the workspace root.
+    - ``${relativeFileDirname}`` – document directory relative to the workspace root.
+    - ``${fileWorkspaceFolder}`` – workspace root folder for the document.
+
+    Variables that do not depend on the document (``${workspaceFolder}``,
+    ``${userHome}``, ``${cwd}``) are pre-resolved by the TypeScript client.
+
+    If no document is available and the value contains any unresolvable
+    file-variable, the workspace root is returned as a fallback.
+
+    See https://code.visualstudio.com/docs/reference/variables-reference
     """
     cwd = settings.get("cwd", settings["workspaceFS"])
-    if "${fileDirname}" in cwd:
-        if document and document.path:
-            cwd = cwd.replace("${fileDirname}", os.path.dirname(document.path))
-        else:
-            cwd = settings["workspaceFS"]
+
+    workspace_fs = settings["workspaceFS"]
+
+    if document and document.path:
+        file_path = document.path
+        file_dir = os.path.dirname(file_path)
+        file_basename = os.path.basename(file_path)
+        file_stem, file_ext = os.path.splitext(file_basename)
+
+        substitutions = {
+            "${file}": file_path,
+            "${fileBasename}": file_basename,
+            "${fileBasenameNoExtension}": file_stem,
+            "${fileExtname}": file_ext,
+            "${fileDirname}": file_dir,
+            "${fileDirnameBasename}": os.path.basename(file_dir),
+            "${relativeFile}": os.path.relpath(file_path, workspace_fs),
+            "${relativeFileDirname}": os.path.relpath(file_dir, workspace_fs),
+            "${fileWorkspaceFolder}": workspace_fs,
+        }
+
+        for token, value in substitutions.items():
+            cwd = cwd.replace(token, value)
+    else:
+        # Without a document we cannot resolve file-related variables.
+        # Fall back to workspace root if any remain.
+        if "${file" in cwd or "${relativeFile" in cwd:
+            cwd = workspace_fs
+
     return cwd
 
 
@@ -410,7 +450,7 @@ def _run_tool_on_document(
     settings = copy.deepcopy(_get_settings_by_document(document))
 
     code_workspace = settings["workspaceFS"]
-    # Pass document so get_cwd can resolve ${fileDirname} to this file's directory.
+    # Pass document so get_cwd can resolve file-related variables for this document.
     cwd = get_cwd(settings, document)
 
     use_path = False

src/test/python_tests/test_get_cwd.py

@@ -0,0 +1,207 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License.
+"""Unit tests for the get_cwd() helper in lsp_server."""
+import os
+import pathlib
+import sys
+import types
+
+# ---------------------------------------------------------------------------
+# Stub out bundled LSP dependencies so lsp_server can be imported without the
+# full VS Code extension environment.
+# ---------------------------------------------------------------------------
+def _setup_mocks():
+    class _MockLS:
+        def __init__(self, **kwargs):
+            pass
+
+        def feature(self, *args, **kwargs):
+            return lambda f: f
+
+        def command(self, *args, **kwargs):
+            return lambda f: f
+
+        def show_message_log(self, *args, **kwargs):
+            pass
+
+        def show_message(self, *args, **kwargs):
+            pass
+
+    mock_server = types.ModuleType("pygls.server")
+    mock_server.LanguageServer = _MockLS
+
+    mock_workspace = types.ModuleType("pygls.workspace")
+    mock_workspace.Document = type("Document", (), {"path": None})
+
+    mock_uris = types.ModuleType("pygls.uris")
+    mock_uris.from_fs_path = lambda p: "file://" + p
+
+    mock_lsp = types.ModuleType("lsprotocol.types")
+    for _name in [
+        "TEXT_DOCUMENT_DID_OPEN", "TEXT_DOCUMENT_DID_SAVE", "TEXT_DOCUMENT_DID_CLOSE",
+        "TEXT_DOCUMENT_FORMATTING", "INITIALIZE", "EXIT", "SHUTDOWN",
+    ]:
+        setattr(mock_lsp, _name, _name)
+    for _name in [
+        "Diagnostic", "DiagnosticSeverity", "DidCloseTextDocumentParams",
+        "DidOpenTextDocumentParams", "DidSaveTextDocumentParams",
+        "DocumentFormattingParams", "InitializeParams", "Position", "Range", "TextEdit",
+    ]:
+        setattr(mock_lsp, _name, type(_name, (), {}))
+    mock_lsp.MessageType = type("MessageType", (), {"Log": 4, "Error": 1, "Warning": 2, "Info": 3})
+
+    for _mod_name, _mod in [
+        ("pygls", types.ModuleType("pygls")),
+        ("pygls.server", mock_server),
+        ("pygls.workspace", mock_workspace),
+        ("pygls.uris", mock_uris),
+        ("lsprotocol", types.ModuleType("lsprotocol")),
+        ("lsprotocol.types", mock_lsp),
+        ("lsp_jsonrpc", types.ModuleType("lsp_jsonrpc")),
+        ("lsp_utils", types.ModuleType("lsp_utils")),
+    ]:
+        if _mod_name not in sys.modules:
+            sys.modules[_mod_name] = _mod
+
+    tool_dir = str(pathlib.Path(__file__).parents[3] / "bundled" / "tool")
+    if tool_dir not in sys.path:
+        sys.path.insert(0, tool_dir)
+
+
+_setup_mocks()
+
+import lsp_server  # noqa: E402
+
+WORKSPACE = "/home/user/myproject"
+
+
+def _make_settings(cwd=None):
+    s = {"workspaceFS": WORKSPACE}
+    if cwd is not None:
+        s["cwd"] = cwd
+    return s
+
+
+def _make_doc(path):
+    doc = types.SimpleNamespace(path=path)
+    return doc
+
+
+# ---------------------------------------------------------------------------
+# No-document (fallback) cases
+# ---------------------------------------------------------------------------
+
+
+def test_no_cwd_no_document_returns_workspace():
+    """When neither cwd nor document is provided, return workspaceFS."""
+    settings = _make_settings()
+    assert lsp_server.get_cwd(settings, None) == WORKSPACE
+
+
+def test_plain_cwd_no_document_returned_unchanged():
+    """A cwd without variables is returned as-is even without a document."""
+    settings = _make_settings(cwd="/custom/path")
+    assert lsp_server.get_cwd(settings, None) == "/custom/path"
+
+
+def test_file_variable_no_document_falls_back_to_workspace():
+    """Unresolvable ${file*} variable with no document falls back to workspaceFS."""
+    for token in [
+        "${file}",
+        "${fileBasename}",
+        "${fileBasenameNoExtension}",
+        "${fileExtname}",
+        "${fileDirname}",
+        "${fileDirnameBasename}",
+        "${fileWorkspaceFolder}",
+    ]:
+        settings = _make_settings(cwd=token + "/extra")
+        assert lsp_server.get_cwd(settings, None) == WORKSPACE, f"Failed for {token}"
+
+
+def test_relative_file_variable_no_document_falls_back_to_workspace():
+    """Unresolvable ${relativeFile*} variable with no document falls back to workspaceFS."""
+    for token in ["${relativeFile}", "${relativeFileDirname}"]:
+        settings = _make_settings(cwd=token)
+        assert lsp_server.get_cwd(settings, None) == WORKSPACE, f"Failed for {token}"
+
+
+# ---------------------------------------------------------------------------
+# With document
+# ---------------------------------------------------------------------------
+
+DOC_PATH = "/home/user/myproject/src/foo.py"
+DOC = _make_doc(DOC_PATH)
+
+
+def test_file_resolved():
+    settings = _make_settings(cwd="${file}")
+    assert lsp_server.get_cwd(settings, DOC) == DOC_PATH
+
+
+def test_file_basename_resolved():
+    settings = _make_settings(cwd="${fileBasename}")
+    assert lsp_server.get_cwd(settings, DOC) == "foo.py"
+
+
+def test_file_basename_no_extension_resolved():
+    settings = _make_settings(cwd="${fileBasenameNoExtension}")
+    assert lsp_server.get_cwd(settings, DOC) == "foo"
+
+
+def test_file_extname_resolved():
+    settings = _make_settings(cwd="${fileExtname}")
+    assert lsp_server.get_cwd(settings, DOC) == ".py"
+
+
+def test_file_dirname_resolved():
+    settings = _make_settings(cwd="${fileDirname}")
+    assert lsp_server.get_cwd(settings, DOC) == "/home/user/myproject/src"
+
+
+def test_file_dirname_basename_resolved():
+    settings = _make_settings(cwd="${fileDirnameBasename}")
+    assert lsp_server.get_cwd(settings, DOC) == "src"
+
+
+def test_relative_file_resolved():
+    settings = _make_settings(cwd="${relativeFile}")
+    assert lsp_server.get_cwd(settings, DOC) == os.path.relpath(DOC_PATH, WORKSPACE)
+
+
+def test_relative_file_dirname_resolved():
+    settings = _make_settings(cwd="${relativeFileDirname}")
+    assert lsp_server.get_cwd(settings, DOC) == os.path.relpath(
+        "/home/user/myproject/src", WORKSPACE
+    )
+
+
+def test_file_workspace_folder_resolved():
+    settings = _make_settings(cwd="${fileWorkspaceFolder}")
+    assert lsp_server.get_cwd(settings, DOC) == WORKSPACE
+
+
+def test_composite_pattern_resolved():
+    """Variables embedded inside a longer path are substituted correctly."""
+    settings = _make_settings(cwd="${fileDirname}/subdir")
+    assert lsp_server.get_cwd(settings, DOC) == "/home/user/myproject/src/subdir"
+
+
+def test_multiple_variables_in_one_cwd():
+    """Multiple different variables in the same cwd string are all resolved."""
+    settings = _make_settings(cwd="${fileDirname}/${fileBasename}")
+    result = lsp_server.get_cwd(settings, DOC)
+    assert result == "/home/user/myproject/src/foo.py"
+
+
+def test_no_variable_in_cwd_unchanged():
+    """A cwd with no variables is returned unchanged even when a document exists."""
+    settings = _make_settings(cwd="/static/path")
+    assert lsp_server.get_cwd(settings, DOC) == "/static/path"
+
+
+def test_document_with_no_path_falls_back_to_workspace():
+    """A document object whose path is falsy triggers the fallback."""
+    doc = types.SimpleNamespace(path="")
+    settings = _make_settings(cwd="${fileDirname}")
+    assert lsp_server.get_cwd(settings, doc) == WORKSPACE