Dashboards: Avoid panic with invalid continue token (#111870)

pkg/registry/apis/dashboard/legacy/token.go

@@ -44,7 +44,9 @@ func readContinueToken(next string) (continueToken, error) {
 	if sub[0] != "folder" {
 		return token, fmt.Errorf("expected folder UID in third slug")
 	}
+	if len(sub) > 1 {
 		token.folder = sub[1]
+	}
 
 	// // Check if the folder filter is the same from the previous query
 	// if q.Requirements.Folder == nil {
@@ -59,6 +61,5 @@ func readContinueToken(next string) (continueToken, error) {
 }
 
 func (r *continueToken) String() string {
-	return fmt.Sprintf("org:%d/start:%d/folder:%s",
+	return fmt.Sprintf("org:%d/start:%d/folder:%s", r.orgId, r.id, r.folder)
-		r.orgId, r.id, r.folder)
 }

pkg/registry/apis/dashboard/legacy/token_test.go

@@ -0,0 +1,118 @@
+package legacy
+
+import (
+	"testing"
+)
+
+func TestReadContinueToken(t *testing.T) {
+	tests := []struct {
+		name      string
+		input     string
+		wantToken continueToken
+		wantErr   bool
+	}{
+		{
+			name:  "empty token",
+			input: "",
+			wantToken: continueToken{
+				orgId:  0,
+				id:     0,
+				folder: "",
+			},
+			wantErr: false,
+		},
+		{
+			name:    "too few parts",
+			input:   "org:1/start:2",
+			wantErr: true,
+		},
+		{
+			name:    "invalid org slug",
+			input:   "foo:1/start:2/folder:abc",
+			wantErr: true,
+		},
+		{
+			name:    "invalid org id",
+			input:   "org:abc/start:2/folder:abc",
+			wantErr: true,
+		},
+		{
+			name:    "invalid start slug",
+			input:   "org:1/foo:2/folder:abc",
+			wantErr: true,
+		},
+		{
+			name:    "invalid start id",
+			input:   "org:1/start:abc/folder:abc",
+			wantErr: true,
+		},
+		{
+			name:    "invalid folder slug",
+			input:   "org:1/start:2/foo:abc",
+			wantErr: true,
+		},
+		{
+			name:  "valid token",
+			input: "org:42/start:100/folder:my-folder",
+			wantToken: continueToken{
+				orgId:  42,
+				id:     100,
+				folder: "my-folder",
+			},
+			wantErr: false,
+		},
+		{
+			name:  "valid token with empty folder",
+			input: "org:42/start:100/folder:",
+			wantToken: continueToken{
+				orgId:  42,
+				id:     100,
+				folder: "",
+			},
+			wantErr: false,
+		},
+		{
+			name:  "folder without value",
+			input: "org:42/start:100/folder", // missing trailing ":"
+			wantToken: continueToken{
+				orgId:  42,
+				id:     100,
+				folder: "",
+			},
+			wantErr: false,
+		},
+		{
+			name:  "missing folder",
+			input: "org:42/start:100",
+			wantToken: continueToken{
+				orgId:  42,
+				id:     100,
+				folder: "",
+			},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			token, err := readContinueToken(tt.input)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("readContinueToken() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !tt.wantErr {
+				if token.orgId != tt.wantToken.orgId || token.id != tt.wantToken.id || token.folder != tt.wantToken.folder {
+					t.Errorf("readContinueToken() got = %+v, want %+v", token, tt.wantToken)
+				}
+			}
+		})
+	}
+}
+
+func TestContinueToken_String(t *testing.T) {
+	token := continueToken{orgId: 5, id: 10, folder: "abc"}
+	want := "org:5/start:10/folder:abc"
+	if got := token.String(); got != want {
+		t.Errorf("continueToken.String() = %q, want %q", got, want)
+	}
+}