feat: Return location info and Hijri date from the prayer times endpoint

pkg/hijricalendar/calendar_test.go

@@ -0,0 +1,45 @@
+package hijricalendar
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestToISODate(t *testing.T) {
+	tests := []struct {
+		name string
+		date time.Time
+		want string
+	}{
+		{
+			name: "ramadan 3 1447",
+			date: time.Date(2026, 2, 20, 0, 0, 0, 0, time.UTC),
+			want: "1447-09-03",
+		},
+		{
+			name: "ramadan 1 1447",
+			date: time.Date(2026, 2, 18, 0, 0, 0, 0, time.UTC),
+			want: "1447-09-01",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := ToISODate(tt.date)
+			require.NotEmpty(t, got)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func TestGregorianToIslamicRange(t *testing.T) {
+	y, m, d := GregorianToIslamic(2026, 2, 20)
+	assert.Positive(t, y)
+	assert.GreaterOrEqual(t, m, 1)
+	assert.LessOrEqual(t, m, 12)
+	assert.GreaterOrEqual(t, d, 1)
+	assert.LessOrEqual(t, d, 30)
+}