taler-typescript-core

commit abc9cad5358c3361b10112cd513f37df8fca249a
parent fc93706981d8cd64ff55503d357c8092bebc7be4
Author: Florian Dold <dold@taler.net>
Date:   Wed, 22 Jul 2026 10:56:51 +0200

wallet: test the maximum deposit amount against unspendable coins

Offering coins whose deposit fee exceeds their value must not lower the
reported maximum.

Diffstat:
M
packages/taler-wallet-core/src/coinSelection.test.ts
 | 
48
++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 48 insertions(+), 0 deletions(-)
diff --git a/packages/taler-wallet-core/src/coinSelection.test.ts b/packages/taler-wallet-core/src/coinSelection.test.ts
@@ -562,3 +562,51 @@ test("prefer exact denom", (t) => {
     },
   });
 });
+
+test("deposit max ignores coins that cost more to deposit than they are worth", (t) => {
+  // The 0.005 denomination has a deposit fee of 0.01, so spending it takes
+  // more from the deposit than it adds.  selectGreedy skips such coins, so
+  // offering them must not lower the reported maximum either.
+  const args = (coinAvailability: AvailableCoinsOfDenom[]) =>
+    [
+      {
+        currency: "KUDOS",
+      },
+      {
+        coinAvailability,
+        currentWireFeePerExchange: {
+          "2": kudos`0`,
+        },
+      },
+    ] as const;
+
+  const withoutDust = testing_getMaxDepositAmountForAvailableCoins(
+    ...args([defaultFeeConfig(kudos`5`, 1)]),
+  );
+  const withDust = testing_getMaxDepositAmountForAvailableCoins(
+    ...args([defaultFeeConfig(kudos`5`, 1), defaultFeeConfig(kudos`0.005`, 10)]),
+  );
+
+  assert.strictEqual(Amounts.stringifyValue(withoutDust.rawAmount), "4.99");
+  assert.strictEqual(
+    Amounts.stringifyValue(withDust.rawAmount),
+    Amounts.stringifyValue(withoutDust.rawAmount),
+  );
+});
+
+test("deposit max is zero when only unspendable coins are available", (t) => {
+  const result = testing_getMaxDepositAmountForAvailableCoins(
+    {
+      currency: "KUDOS",
+    },
+    {
+      coinAvailability: [defaultFeeConfig(kudos`0.005`, 10)],
+      currentWireFeePerExchange: {
+        "2": kudos`1`,
+      },
+    },
+  );
+
+  assert.strictEqual(Amounts.stringifyValue(result.rawAmount), "0");
+  assert.strictEqual(Amounts.stringifyValue(result.effectiveAmount), "0");
+});