test(adcp): docstring/env-var consistency test

tests/test_docstring_consistency.py

@@ -0,0 +1,202 @@
+"""Ensure env-var names in public docstrings are backed by actual
+``os.environ`` reads in the source tree.
+
+Motivated by the drift in ``client.py:381-388``: the docstring claimed
+``PYTHON_ENV`` / ``ENV`` / ``ENVIRONMENT`` were honored; only ``ADCP_ENV``
+was. This test prevents that class of documentation drift from re-entering
+silently.
+
+Detection rules (applied per docstring line, with a ±1-line window for
+Pattern B context keywords):
+
+- **Pattern A** ``VARNAME=value`` — RST double-backtick env-var assignment
+  syntax, e.g. `` ``ADCP_VALIDATION_MODE=strict|warn|off`` ``.
+- **Pattern B** SCREAMING_CASE_WITH_UNDERSCORE inside a double-backtick span
+  on a line whose ±1 neighborhood contains an env-var context keyword
+  (``environ``, ``env var``, ``environment variable``, ``flips``). Restricted
+  to backtick-wrapped tokens to prevent false positives from protocol
+  constants or OOP-override prose (e.g. "this method overrides HTTP_TIMEOUT").
+  "overrides" is intentionally excluded as a standalone keyword for the same
+  reason; legitimate override docs use ``VARNAME=value`` or "VARNAME env var".
+
+Exclusion: lines containing ``deliberately`` or ``not honored`` are skipped —
+the var is explicitly documented as inactive on that line. Bare "ignored" is
+not an exclusion keyword to avoid suppressing real checks when a docstring
+says "X is ignored when Y is set explicitly."
+
+Known limitations:
+- Single-token env vars without underscores (e.g. ``PORT``) are invisible to
+  both patterns; the regex requires at least one underscore to distinguish env
+  vars from acronyms and other short tokens.
+- ``_env_vars_in_use()`` scans raw source text, so ``os.environ`` calls that
+  appear inside docstring examples are included in the "in use" set. A future
+  docstring embedding a fictional ``os.environ["FAKE_VAR"]`` call would
+  suppress detection of that name. This is an accepted trade-off for
+  simplicity.
+- ``ast.walk`` collects public methods defined inside private classes. This is
+  a known over-approximation; fixing it requires tracking parent scope.
+"""
+
+from __future__ import annotations
+
+import ast
+import re
+from pathlib import Path
+
+SRC_ROOT = Path(__file__).parent.parent / "src" / "adcp"
+
+# Pattern A: ``VARNAME=anything`` inside RST double-backtick literals.
+# Captures the var name without the trailing ``=``.
+_ASSIGNMENT_PATTERN = re.compile(r"``([A-Z][A-Z0-9]*(?:_[A-Z0-9]+)+)=")
+
+# Pattern B — step 1: extract double-backtick span contents.
+_BACKTICK_SPAN = re.compile(r"``([^`]+)``")
+
+# Pattern B — step 2: find SCREAMING_CASE_WITH_UNDERSCORE inside a span.
+# Two-step avoids greedy-match bugs where a single regex would capture a
+# suffix like ``P_ENV`` from ``ADCP_ENV``.
+_SCREAMING_WITH_UNDERSCORE = re.compile(r"\b([A-Z][A-Z0-9]*(?:_[A-Z0-9]+)+)\b")
+
+# Context keywords for Pattern B. Present in the line's ±1 neighborhood, they
+# indicate the backtick-wrapped token is an env var. "overrides" is excluded
+# (see module docstring) to prevent OOP-override false positives.
+_ENV_CONTEXT_RE = re.compile(
+    r"\benviron\b|\benv var\b|\benvironment variable\b|\bflips?\b",
+    re.IGNORECASE,
+)
+
+# Words that, on the SAME line as a token, explicitly mark it as inactive.
+# Bare "ignored" is excluded: "X is ignored when Y is set" would suppress
+# legitimate checks if we matched it.
+_IGNORE_CONTEXT_RE = re.compile(
+    r"\bdeliberately\b|\bnot honored\b",
+    re.IGNORECASE,
+)
+
+# All the ways the source code reads env vars:
+#   os.environ.get("VAR"), os.getenv("VAR"), os.environ["VAR"]
+_ENVIRON_READ_RE = re.compile(
+    r"""(?:os\.environ\.get|os\.getenv)\(\s*['"]([A-Z][A-Z0-9_]+)['"]\s*"""
+    r"""|os\.environ\[\s*['"]([A-Z][A-Z0-9_]+)['"]\s*\]"""
+)
+
+
+def _env_vars_in_use() -> frozenset[str]:
+    """Return all env var names read by any file under src/adcp/.
+
+    Scans raw source text; see module docstring for the known limitation about
+    os.environ calls embedded in docstring examples.
+    """
+    found: set[str] = set()
+    for path in SRC_ROOT.rglob("*.py"):
+        src = path.read_text(encoding="utf-8")
+        for m in _ENVIRON_READ_RE.finditer(src):
+            var = m.group(1) or m.group(2)
+            if var:
+                found.add(var)
+    return frozenset(found)
+
+
+def _collect_docstrings(tree: ast.Module) -> list[tuple[str, int]]:
+    """Return (docstring, lineno) for all public nodes, including dunders.
+
+    See module docstring for the known limitation about public methods inside
+    private classes.
+    """
+    results: list[tuple[str, int]] = []
+    for node in ast.walk(tree):
+        name: str = getattr(node, "name", "") or ""
+        # Include dunder methods (__init__, __str__, …) — their docstrings are
+        # user-facing. Skip single-leading-underscore private names only.
+        if name.startswith("_") and not (name.startswith("__") and name.endswith("__")):
+            continue
+        if not isinstance(
+            node, (ast.Module, ast.ClassDef, ast.FunctionDef, ast.AsyncFunctionDef)
+        ):
+            continue
+        doc = ast.get_docstring(node)
+        if doc:
+            # ast.Module has no lineno; use 1 since module docstrings are at
+            # the top of the file.
+            lineno = getattr(node, "lineno", 1)
+            results.append((doc, lineno))
+    return results
+
+
+def _env_vars_from_docstring(doc: str) -> set[str]:
+    """Extract env var names documented as active in this docstring.
+
+    Uses a ±1-line window for Pattern B so that a context keyword on the line
+    immediately after the env-var reference is still detected (e.g.
+    ``ADCP_ENV`` on one line, ``flips …`` on the next).
+    """
+    lines = doc.splitlines()
+    found: set[str] = set()
+
+    for i, line in enumerate(lines):
+        # Pattern A: ``VARNAME=...`` assignment syntax — line-local check.
+        if not _IGNORE_CONTEXT_RE.search(line):
+            for m in _ASSIGNMENT_PATTERN.finditer(line):
+                found.add(m.group(1))
+
+        # Pattern B: backtick-wrapped SCREAMING_CASE in env-var context.
+        if _IGNORE_CONTEXT_RE.search(line):
+            continue  # this line explicitly marks var(s) as inactive
+
+        # Collect SCREAMING_CASE tokens from inside each ``...`` span.
+        screaming_vars = [
+            vm.group(1)
+            for sm in _BACKTICK_SPAN.finditer(line)
+            for vm in _SCREAMING_WITH_UNDERSCORE.finditer(sm.group(1))
+        ]
+        if not screaming_vars:
+            continue
+
+        # Context keyword may be on this line or an immediate neighbor (±1).
+        window = [line]
+        if i > 0:
+            window.append(lines[i - 1])
+        if i < len(lines) - 1:
+            window.append(lines[i + 1])
+        if any(_ENV_CONTEXT_RE.search(w) for w in window):
+            found.update(screaming_vars)
+
+    return found
+
+
+def test_docstring_env_var_consistency() -> None:
+    """Every env-var name documented as active in a public docstring must
+    have a matching ``os.environ`` read somewhere in ``src/adcp/``.
+
+    A violation means either:
+    - the implementation was removed but the docs were not updated, or
+    - the docs claim an override that was never implemented.
+
+    Fix: add the missing ``os.environ.get(...)`` call, or add the phrase
+    'deliberately ignored' to the docstring line.
+    """
+    in_use = _env_vars_in_use()
+    violations: list[str] = []
+
+    for filepath in sorted(SRC_ROOT.rglob("*.py")):
+        try:
+            source = filepath.read_text(encoding="utf-8")
+            tree = ast.parse(source, filename=str(filepath))
+        except SyntaxError:
+            # Syntax errors are caught by dedicated CI checks; skip here.
+            continue  # pragma: no cover
+
+        rel = str(filepath.relative_to(SRC_ROOT.parent.parent))
+        for doc, lineno in _collect_docstrings(tree):
+            for var in _env_vars_from_docstring(doc):
+                if var not in in_use:
+                    violations.append(
+                        f"{rel}:{lineno}: docstring references {var!r} "
+                        f"but no os.environ read of {var!r} found in src/adcp/"
+                    )
+
+    assert not violations, (
+        "Docstring/code env-var drift detected.\n"
+        "Either add the missing os.environ read, or mark the var as "
+        "'deliberately ignored' in the docstring.\n\n" + "\n".join(violations)
+    )