1 files changed, 199 insertions, 0 deletions
diff --git a/exchange_test.go b/exchange_test.go
new file mode 100644
index 0000000..dcb68b1
--- /dev/null
+++ b/exchange_test.go
@@ -0,0 +1,199 @@
+package exchange
+
+import (
+	"bytes"
+	"encoding/json"
+	"log"
+	"net/url"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/google/go-querystring/query"
+	"github.com/shopspring/decimal"
+	"github.com/stretchr/testify/require"
+)
+
+const (
+	keyFile = ".key"
+
+	// $1 CAD ≅ 70¢ USD (±20%)
+	// This is the rate at the time of writing. It may need to be
+	// changed later if something drastic occurs in either country.
+	usdPerCad   = 0.70
+	rateEpsilon = 0.20
+
+	floatEpsilon = 1e-7
+)
+
+var apiKey string
+
+func TestMain(m *testing.M) {
+	debug = true
+
+	// Load API key
+	buf, err := os.ReadFile(keyFile)
+	if err != nil {
+		log.Fatalf("error loading API key: %v\n", err)
+	}
+	apiKey = string(bytes.TrimSpace(buf))
+
+	m.Run()
+}
+
+func TestUnmarshalApiError(t *testing.T) {
+	data := `
+{
+  "status": {
+    "timestamp": "2018-06-02T22:51:28.209Z",
+    "error_code": 1002,
+    "error_message": "API key missing.",
+    "elapsed": 10,
+    "credit_count": 0
+  }
+}
+`
+	want := apiError{
+		status{"API key missing."},
+	}
+	var info apiError
+	err := json.Unmarshal([]byte(data), &info)
+	require.NoError(t, err)
+	require.Equal(t, want, info)
+}
+
+func TestPriceConversionQuery(t *testing.T) {
+	q := priceConversionQuery{123, "USD", "CAD"}
+	want := url.Values{
+		"amount":  {"123"},
+		"symbol":  {"USD"},
+		"convert": {"CAD"},
+	}
+	vals, err := query.Values(q)
+	require.NoError(t, err)
+	require.Equal(t, want, vals)
+}
+
+func TestUnmarshalPriceConversionResponse(t *testing.T) {
+	data := `
+{
+  "data": [
+    {
+      "id": 32134,
+      "symbol": "CAD",
+      "name": "Caduceus Protocol (new)",
+      "amount": 1,
+      "quote": {
+        "USD": {
+          "price": 0.00026617250802605987,
+          "last_updated": "2026-07-09T17:31:05.000Z"
+        }
+      },
+      "last_updated": "2026-07-09T17:30:00.000Z"
+    },
+    {
+      "id": 2784,
+      "symbol": "CAD",
+      "name": "Canadian Dollar",
+      "amount": 1,
+      "quote": {
+        "USD": {
+          "price": 0.7060965078585,
+          "last_updated": "2026-07-09T17:31:05.000Z"
+        }
+      },
+      "last_updated": "2026-07-09T17:31:05.000Z"
+    }
+  ],
+  "status": {
+    "timestamp": "2026-07-09T17:32:29.378Z",
+    "error_code": 0,
+    "error_message": null,
+    "elapsed": 25,
+    "credit_count": 1,
+    "notice": null
+  }
+}
+
+`
+	want := response[[]priceConversion]{
+		Data: []priceConversion{
+			{
+				32134,
+				map[string]price{
+					"USD": {decimal.RequireFromString("0.00026617250802605987")},
+				},
+			}, {
+				2784,
+				map[string]price{
+					"USD": {decimal.RequireFromString("0.7060965078585")},
+				},
+			},
+		},
+	}
+	var conv response[[]priceConversion]
+	err := json.Unmarshal([]byte(data), &conv)
+	require.NoError(t, err)
+	require.Equal(t, want, conv)
+}
+
+func TestRateCache(t *testing.T) {
+	clnt := NewClient(apiKey)
+	defer clnt.Close()
+	from, to := "CAD", "USD"
+
+	// Repeat to exercise cache
+	for i := 0; i < 5; i++ {
+		rate, err := clnt.Rate(from, to)
+		require.NoError(t, err)
+		t.Log(rate)
+		require.InEpsilon(t, usdPerCad, rate.InexactFloat64(), rateEpsilon)
+	}
+}
+
+func TestRateCacheExpire(t *testing.T) {
+	ttl := time.Millisecond
+	clnt := NewClient(apiKey, WithTTL(ttl))
+	defer clnt.Close()
+	from, to := "CAD", "USD"
+	check := func() {
+		rate, err := clnt.Rate(from, to)
+		require.NoError(t, err)
+		t.Log(rate)
+		require.InEpsilon(t, usdPerCad, rate.InexactFloat64(), rateEpsilon)
+	}
+	check()             // retrieve
+	time.Sleep(2 * ttl) // expire
+	check()             // refresh
+}
+
+func TestRateFiatFiat(t *testing.T) {
+	testRate(t, "AUD", "CAD")
+}
+
+func TestRateFiatCrypto(t *testing.T) {
+	testRate(t, "CAD", "XMR")
+}
+
+func TestRateCryptoCrypto(t *testing.T) {
+	testRate(t, "XMR", "BTC")
+}
+
+func testRate(t *testing.T, from, to string) {
+	c := NewClient(apiKey)
+	defer c.Close()
+
+	aPerB := rate(t, c, from, to)
+	bPerA := rate(t, c, to, from)
+	require.NotZero(t, aPerB)
+	require.NotZero(t, bPerA)
+	require.InEpsilon(t, bPerA.InexactFloat64(), decimal.NewFromInt(1).Div(aPerB).InexactFloat64(), floatEpsilon)
+}
+
+func rate(t *testing.T, c *Client, from, to string) decimal.Decimal {
+	t.Helper()
+	rate, err := c.Rate(from, to)
+	require.NoError(t, err)
+	t.Logf("1 %s = %v %s\n", from, rate, to)
+	return rate
+}