2 files changed, 103 insertions, 0 deletions
diff --git a/pkg/stack/stack-stack.go b/pkg/stack/stack-stack.go
index db5a405..adc41c6 100644
--- a/pkg/stack/stack-stack.go
+++ b/pkg/stack/stack-stack.go
@@ -17,6 +17,7 @@ func NewStackStack() *StackStack {
 }
 
 func (ss *StackStack) Begin(p *pointer.Pointer) {
+	ss.height++
 	soss := ss.head
 	n := soss.Pop()
 	np := n
diff --git a/pkg/stack/stack-stack_test.go b/pkg/stack/stack-stack_test.go
new file mode 100644
index 0000000..6c0c47f
--- /dev/null
+++ b/pkg/stack/stack-stack_test.go
@@ -0,0 +1,102 @@
+package stack
+
+import (
+	"os"
+	"testing"
+
+	"git.adyxax.org/adyxax/gofunge/pkg/field"
+	"git.adyxax.org/adyxax/gofunge/pkg/pointer"
+	"github.com/stretchr/testify/require"
+)
+
+func TestBegin(t *testing.T) {
+	t.Run("empty", func(t *testing.T) {
+		expected := NewStackStack()
+		expected.head = &Stack{data: make([]int, 0), next: expected.head}
+		expected.head.next.Push(0)
+		expected.head.next.Push(0)
+		expected.height++
+		ss := NewStackStack()
+		p := pointer.NewPointer()
+		ss.Begin(p)
+		require.Equal(t, expected, ss)
+		x, y := p.GetStorageOffset()
+		require.Equal(t, 1, x)
+		require.Equal(t, 0, y)
+		// Let's push another one
+		expected.head = &Stack{data: make([]int, 0), next: expected.head}
+		expected.head.next.Push(1)
+		expected.head.next.Push(0)
+		expected.height++
+		ss.Begin(p)
+		require.Equal(t, expected, ss)
+		x, y = p.GetStorageOffset()
+		require.Equal(t, 1, x)
+		require.Equal(t, 0, y)
+	})
+	t.Run("negative", func(t *testing.T) {
+		expected := NewStackStack()
+		expected.head = &Stack{size: 5, height: 5, data: make([]int, 5), next: expected.head}
+		expected.head.next.Push(0)
+		expected.head.next.Push(0)
+		expected.height++
+		p := pointer.NewPointer()
+		file, err := os.Open("../field/test_data/hello.b98")
+		require.NoError(t, err, "Failed to open file")
+		f, err := field.Load(file)
+		p.Step(*f)
+		ss := NewStackStack()
+		ss.head.Push(-5)
+		ss.Begin(p)
+		require.Equal(t, expected, ss)
+		x, y := p.GetStorageOffset()
+		require.Equal(t, 2, x)
+		require.Equal(t, 0, y)
+	})
+	t.Run("ask to copy more than we have", func(t *testing.T) {
+		expected := NewStackStack()
+		expected.head = &Stack{size: 34, height: 34, data: make([]int, 34), next: expected.head}
+		expected.head.data[33] = 18
+		expected.head.next.Push(18)
+		expected.head.next.Push(2)
+		expected.head.next.Push(3)
+		expected.height++
+		p := pointer.NewPointer()
+		p.SetStorageOffset(2, 3)
+		file, err := os.Open("../field/test_data/hello.b98")
+		require.NoError(t, err, "Failed to open file")
+		f, err := field.Load(file)
+		p.Step(*f)
+		ss := NewStackStack()
+		ss.head.Push(18)
+		ss.head.Push(34)
+		ss.Begin(p)
+		require.Equal(t, expected, ss)
+		x, y := p.GetStorageOffset()
+		require.Equal(t, 2, x)
+		require.Equal(t, 0, y)
+	})
+	t.Run("normal", func(t *testing.T) {
+		expected := NewStackStack()
+		expected.head = &Stack{size: 4, height: 4, data: []int{12, 14, -2, 5}, next: expected.head}
+		expected.head.next.Push(7)
+		expected.head.next.Push(12)
+		expected.head.next.Push(14)
+		expected.head.next.Push(-2)
+		expected.head.next.Push(5)
+		expected.head.next.Push(36)
+		expected.head.next.Push(42)
+		expected.height++
+		p := pointer.NewPointer()
+		p.SetStorageOffset(36, 42)
+		ss := NewStackStack()
+		ss.head.Push(7)
+		ss.head.Push(12)
+		ss.head.Push(14)
+		ss.head.Push(-2)
+		ss.head.Push(5)
+		ss.head.Push(4)
+		ss.Begin(p)
+		require.Equal(t, expected, ss)
+	})
+}