Add app_config.py: config.json loader, validation, env-precedence resolvers

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VPNF37MP9Kuv62B1VBrZ1b

test_all.py

@@ -18,6 +18,20 @@ import pandas as pd
 
 sys.path.insert(0, os.path.dirname(__file__))
 
+# ── Hermetic app-config: the suite must not depend on the developer's
+#    local config.json or TELEGRAM_*/TWELVE_DATA_API_KEY env vars. The
+#    dummy TD key mirrors the pre-config.json behavior where a key was
+#    always present (TDClient built, no network at construction).
+import json
+import app_config
+for _k in ("TELEGRAM_TOKEN", "TELEGRAM_CHAT_ID", "TELEGRAM_CHANNEL_ID",
+           "TWELVE_DATA_API_KEY"):
+    os.environ.pop(_k, None)
+_TEST_APP = app_config.AppConfig(
+    provider_settings={"twelve_data": {"api_key": "test-key"}}
+)
+app_config.set_app_config(_TEST_APP)
+
 PASS = 0
 FAIL = 0
 ERRORS = []
@@ -2525,6 +2539,128 @@ def _():
     assert args2.cp is False
 
 
+# ══════════════════════════════════════════════════════════════════════
+#  MODULE 13: app_config.py (config.json overlay)
+# ══════════════════════════════════════════════════════════════════════
+print("\n═══ Module 13: app_config.py ═══")
+
+import tempfile
+from app_config import (
+    AppConfig, AppConfigError, load_app_config, set_app_config,
+    telegram_token, telegram_chat_id, telegram_channel_id,
+    provider_api_key, apply_pair_overrides,
+)
+
+
+def _write_json(payload) -> str:
+    fh = tempfile.NamedTemporaryFile(
+        "w", suffix=".json", delete=False, encoding="utf-8")
+    if isinstance(payload, str):
+        fh.write(payload)
+    else:
+        json.dump(payload, fh)
+    fh.close()
+    return fh.name
+
+
+_FULL_CFG = {
+    "telegram": {"token": "t0k", "chat_id": "111", "channel_id": "-100222",
+                 "alert_min_quality": "B"},
+    "data_providers": {"active": "twelve_data",
+                       "twelve_data": {"api_key": "json-key"}},
+    "scanning": {"pairs": ["XAU/USD"], "timeframes": ["M15", "H1"]},
+    "pairs": {"XAU/USD": {"blocked_hours_utc": [3, 4]}},
+    "log_level": "WARNING",
+}
+
+
+@test("app_config: valid config.json maps every field")
+def _():
+    app = load_app_config(_write_json(_FULL_CFG))
+    assert app.telegram_token == "t0k"
+    assert app.telegram_chat_id == "111"
+    assert app.telegram_channel_id == "-100222"
+    assert app.alert_min_quality == "B"
+    assert app.active_provider == "twelve_data"
+    assert app.provider_settings["twelve_data"]["api_key"] == "json-key"
+    assert app.scan_pairs == [XAUUSD]
+    assert app.scan_timeframes == [Timeframe.M15, Timeframe.H1]
+    assert app.pair_overrides[XAUUSD]["blocked_hours_utc"] == [3, 4]
+    assert app.log_level == "WARNING"
+
+
+@test("app_config: missing file returns pure defaults")
+def _():
+    app = load_app_config("/nonexistent/config.json")
+    assert app == AppConfig(), "absent config.json must yield pure defaults"
+
+
+@test("app_config: malformed JSON raises AppConfigError")
+def _():
+    path = _write_json("{not json")
+    try:
+        load_app_config(path)
+        assert False, "should have raised"
+    except AppConfigError as e:
+        assert "not valid JSON" in str(e)
+
+
+@test("app_config: unknown keys raise AppConfigError")
+def _():
+    for payload in (
+        {"telgram": {}},                                   # top-level typo
+        {"telegram": {"tokn": "x"}},                       # section typo
+        {"pairs": {"XAU/USD": {"blocked_hours": [1]}}},    # pair-block typo
+        {"scanning": {"pair": ["XAU/USD"]}},               # scanning typo
+    ):
+        try:
+            load_app_config(_write_json(payload))
+            assert False, f"should have raised for {payload}"
+        except AppConfigError as e:
+            assert "unknown key" in str(e).lower()
+
+
+@test("app_config: invalid values raise AppConfigError")
+def _():
+    bad_payloads = [
+        {"pairs": {"XAU/USD": {"blocked_hours_utc": [24]}}},      # hour range
+        {"pairs": {"XAU/USD": {"blocked_hours_utc": "3"}}},       # not a list
+        {"pairs": {"EUR/USD": {"blocked_hours_utc": [3]}}},       # unknown pair
+        {"scanning": {"pairs": ["EUR/USD"]}},                     # unknown pair
+        {"scanning": {"timeframes": ["M7"]}},                     # bad TF name
+        {"scanning": {"timeframes": ["W1"]}},                     # unscannable TF
+        {"data_providers": {"active": "polygon",
+                            "twelve_data": {"api_key": "k"}}},    # no block
+        {"telegram": {"alert_min_quality": "Z"}},                 # bad quality
+        {"log_level": "CHATTY"},                                  # bad level
+    ]
+    for payload in bad_payloads:
+        try:
+            load_app_config(_write_json(payload))
+            assert False, f"should have raised for {payload}"
+        except AppConfigError:
+            pass
+
+
+@test("app_config: env precedence env → config.json → default")
+def _():
+    app = load_app_config(_write_json(_FULL_CFG))
+    with patch.dict(os.environ, {}, clear=True):
+        assert telegram_token(app) == "t0k"
+        assert telegram_chat_id(app) == "111"
+        assert telegram_channel_id(app) == "-100222"
+        assert provider_api_key(app) == "json-key"
+    with patch.dict(os.environ, {"TELEGRAM_TOKEN": "env-tok",
+                                 "TELEGRAM_CHAT_ID": "999",
+                                 "TWELVE_DATA_API_KEY": "env-key"}):
+        assert telegram_token(app) == "env-tok"
+        assert telegram_chat_id(app) == "999"
+        assert provider_api_key(app) == "env-key"
+    # channel: env set-but-empty means "disable feed" and must beat JSON
+    with patch.dict(os.environ, {"TELEGRAM_CHANNEL_ID": ""}):
+        assert telegram_channel_id(app) == ""
+
+
 # ══════════════════════════════════════════════════════════════════════
 #  SUMMARY
 # ══════════════════════════════════════════════════════════════════════