better rbtree diagnostics

2 files changed, 38 insertions, 36 deletions

diff --git a/pkg/rbtree/print_test.go b/pkg/rbtree/print_test.go
new file mode 100644
index 0000000..c4154c8
--- /dev/null
+++ b/pkg/rbtree/print_test.go
@@ -0,0 +1,30 @@
+package rbtree
+
+import (
+	"fmt"
+	"io"
+	"strings"
+)
+
+func (t *Tree[K, V]) ASCIIArt() string {
+	var out strings.Builder
+	t.root.asciiArt(&out, "", "", "")
+	return out.String()
+}
+
+func (node *Node[V]) asciiArt(w io.Writer, u, m, l string) {
+	if node == nil {
+		fmt.Fprintf(w, "%snil\n", m)
+		return
+	}
+
+	node.Right.asciiArt(w, u+"     ", u+"  ,--", u+"  |  ")
+
+	if node.Color == Red {
+		fmt.Fprintf(w, "%sR(%v)\n", m, node.Value)
+	} else {
+		fmt.Fprintf(w, "%sB(%v)\n", m, node.Value)
+	}
+
+	node.Left.asciiArt(w, l+"  |  ", l+"  `--", l+"     ")
+}
diff --git a/pkg/rbtree/rbtree_test.go b/pkg/rbtree/rbtree_test.go
index 6c49127..7b3987f 100644
--- a/pkg/rbtree/rbtree_test.go
+++ b/pkg/rbtree/rbtree_test.go
@@ -1,8 +1,6 @@
 package rbtree
 
 import (
-	"fmt"
-	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -10,37 +8,6 @@ import (
 	"golang.org/x/exp/constraints"
 )
 
-func printTree[K constraints.Ordered, V any](t *testing.T, tree *Tree[K, V]) {
-	fmtBareNode := func(node *Node[V]) string {
-		if node == nil {
-			return "nil"
-		}
-		if node.Color == Red {
-			return fmt.Sprintf("R(%v)", node.Value)
-		} else {
-			return fmt.Sprintf("B(%v)", node.Value)
-		}
-	}
-	addIndent := func(indent string, lines []string) []string {
-		ret := make([]string, 0, len(lines))
-		for _, line := range lines {
-			ret = append(ret, indent+line)
-		}
-		return ret
-	}
-	var fmtNode func(node *Node[V]) []string
-	fmtNode = func(node *Node[V]) []string {
-		if node == nil {
-			return []string{"nil"}
-		}
-		ret := addIndent("    ", fmtNode(node.Right))
-		ret = append(ret, fmtBareNode(node))
-		ret = append(ret, addIndent("    ", fmtNode(node.Left))...)
-		return ret
-	}
-	t.Log("\n" + strings.Join(fmtNode(tree.root), "\n"))
-}
-
 func checkTree[K constraints.Ordered, V any](t *testing.T, tree *Tree[K, V]) {
 	// 1. Every node is either red or black
 
@@ -79,9 +46,8 @@ func checkTree[K constraints.Ordered, V any](t *testing.T, tree *Tree[K, V]) {
 		})
 		for i := range cnts {
 			if cnts[0] != cnts[i] {
-				if !assert.Truef(t, false, "node %v: not all leafs have same black-count: %v", node.Value, cnts) {
-					printTree(t, tree)
-				}
+				assert.Truef(t, false, "node %v: not all leafs have same black-count: %v", node.Value, cnts)
+				break
 			}
 		}
 	})
@@ -125,7 +91,13 @@ func FuzzTree(f *testing.F) {
 				assert.Equal(t, val, node.Value)
 			} else {
 				t.Logf("Delete(%v)", val)
+				if val == 25 {
+					t.Logf("before:\n\n%s\n", tree.ASCIIArt())
+				}
 				tree.Delete(val)
+				if val == 25 {
+					t.Logf("after:\n\n%s\n", tree.ASCIIArt())
+				}
 				assert.Nil(t, tree.Lookup(val))
 			}
 			checkTree(t, tree)