diff --git a/ledger/file_test.go b/ledger/file_test.go
new file mode 100644
index 0000000..33d6410
--- /dev/null
+++ b/ledger/file_test.go
@@ -0,0 +1,58 @@
+package ledger
+
+import (
+	"testing"
+	"time"
+)
+
+func TestFileDeltas(t *testing.T) {
+	f, err := NewFile("./testdata/happy.dat")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	deltas, err := f.Deltas()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	d := func(s string) time.Time {
+		v, _ := time.Parse("2006-01-02", s)
+		return v
+	}
+	want := []Delta{
+		{
+			Date:     d("2022-12-12"),
+			Account:  "AssetAccount:Cash:Fidelity76",
+			Value:    -97.92,
+			Currency: USD,
+		},
+		{
+			Date:     d("2022-12-12"),
+			Account:  "Withdrawal:0:SharedHome:DominionEnergy",
+			Value:    97.92,
+			Currency: USD,
+		},
+		{
+			Date:     d("2022-12-12"),
+			Account:  "AssetAccount:Cash:Fidelity76",
+			Value:    -1.00,
+			Currency: USD,
+		},
+		{
+			Date:     d("2022-12-12"),
+			Account:  "Debts:Credit:ChaseFreedomUltdVisa",
+			Value:    1.00,
+			Currency: USD,
+		},
+	}
+
+	if len(deltas) != len(want) {
+		t.Error(len(deltas))
+	}
+	for i := range want {
+		if want[i] != deltas[i] {
+			t.Errorf("[%d] want=%+v, got=%+v", i, want[i], deltas[i])
+		}
+	}
+}
diff --git a/ledger/testdata/happy.dat b/ledger/testdata/happy.dat
new file mode 100644
index 0000000..027dcb7
--- /dev/null
+++ b/ledger/testdata/happy.dat
@@ -0,0 +1,7 @@
+2022-12-12   Electricity / Power Bill TG2PJ-2PLP5 OK
+         AssetAccount:Cash:Fidelity76                                                                         $-97.92
+         Withdrawal:0:SharedHome:DominionEnergy
+2022-12-12   Test pay chase TG32S-BT2FF OK
+         AssetAccount:Cash:Fidelity76                                                                         $-1.00
+         Debts:Credit:ChaseFreedomUltdVisa
+