test reimplementation of brmbar.Currency.rates method

brmbar3/brmbar/Currency.py

@@ -57,6 +57,23 @@ class Currency:
 
         return (buy, sell)
 
+    def rates2(self, other):
+        # the original code for compare testing
+        res = self.db.execute_and_fetch("SELECT rate, rate_dir FROM exchange_rates WHERE target = %s AND source = %s AND valid_since <= NOW() ORDER BY valid_since DESC LIMIT 1", [self.id, other.id])
+        if res is None:
+            raise NameError("Currency.rate(): Unknown conversion " + other.name() + " to " + self.name())
+        buy_rate, buy_rate_dir = res
+        buy = buy_rate if buy_rate_dir == "target_to_source" else 1/buy_rate
+
+        res = self.db.execute_and_fetch("SELECT rate, rate_dir FROM exchange_rates WHERE target = %s AND source = %s AND valid_since <= NOW() ORDER BY valid_since DESC LIMIT 1", [other.id, self.id])
+        if res is None:
+            raise NameError("Currency.rate(): Unknown conversion " + self.name() + " to " + other.name())
+        sell_rate, sell_rate_dir = res
+        sell = sell_rate if sell_rate_dir == "source_to_target" else 1/sell_rate
+
+        return (buy, sell)
+
+
     def convert(self, amount, target):
         res = self.db.execute_and_fetch("SELECT rate, rate_dir FROM exchange_rates WHERE target = %s AND source = %s AND valid_since <= NOW() ORDER BY valid_since DESC LIMIT 1", [target.id, self.id])
         if res is None:

brmbar3/test--currency-rates.py

@@ -0,0 +1,73 @@
+#!/usr/bin/python3
+
+import sys
+import subprocess
+
+#from brmbar import Database
+#from brmbar import Currency
+
+from contextlib import closing
+import psycopg2
+from brmbar.Database import Database
+from brmbar.Currency import Currency
+import math
+
+#import brmbar
+
+
+
+def approx_equal(a, b, tol=1e-6):
+    """Check if two (buy, sell) rate tuples are approximately equal."""
+    return (
+        isinstance(a, tuple) and isinstance(b, tuple) and
+        math.isclose(a[0], b[0], abs_tol=tol) and
+        math.isclose(a[1], b[1], abs_tol=tol)
+    )
+
+def compare_exceptions(e1, e2):
+    """Compare exception types and messages."""
+    return type(e1) == type(e2) and str(e1) == str(e2)
+
+def main():
+    db = Database("dbname=brmbar")
+
+    # Get all currencies
+    with closing(db.db_conn.cursor()) as cur:
+        cur.execute("SELECT id, name FROM currencies")
+        currencies = cur.fetchall()
+
+    # Build Currency objects
+    currency_objs = [Currency(db, id, name) for id, name in currencies]
+
+    # Test all currency pairs
+    for c1 in currency_objs:
+        for c2 in currency_objs:
+            #if c1.id == c2.id:
+            #    continue
+
+            try:
+                rates1 = c1.rates(c2)
+                exc1 = None
+            except (RuntimeError, NameError) as e1:
+                rates1 = None
+                exc1 = e1
+
+            try:
+                rates2 = c1.rates2(c2)
+                exc2 = None
+            except (RuntimeError, NameError) as e2:
+                rates2 = None
+                exc2 = e2
+
+            if exc1 or exc2:
+                if not compare_exceptions(exc1, exc2):
+                    print(f"[EXCEPTION DIFFERENCE] {c1.name} -> {c2.name}")
+                    print(f"  rates() exception:  {type(exc1).__name__}: {exc1}")
+                    print(f"  rates2() exception: {type(exc2).__name__}: {exc2}")
+            elif not approx_equal(rates1, rates2):
+                print(f"[VALUE DIFFERENCE] {c1.name} -> {c2.name}")
+                print(f"  rates():  {rates1}")
+                print(f"  rates2(): {rates2}")
+
+if __name__ == "__main__":
+    main()