diff --git a/py/power_puter.py b/py/power_puter.py
index 669d40a..ca04135 100644
--- a/py/power_puter.py
+++ b/py/power_puter.py
@@ -510,11 +510,9 @@ class _Puter:
       else:
         # Slice could be a name or a constant; evaluate it
         attr = self._eval_statement(stmt.slice, ctx=ctx)
-      if not isinstance(attr, str):
-        raise ValueError(f'Disallowed access to "{attr}"')
       # Check if we're blocking access to this attribute/method on this item type.
       for typ, names in _BLOCKED_METHODS_OR_ATTRS.items():
-        if isinstance(item, typ) and attr in names:
+        if isinstance(item, typ) and isinstance(attr, str) and attr in names:
           raise ValueError(f'Disallowed access to "{attr}" for type {typ}.')
       try:
         val = item[attr]
diff --git a/pyproject.toml b/pyproject.toml
index 0680d84..7a6ad66 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,7 +1,7 @@
 [project]
 name = "rgthree-comfy"
 description = "Making ComfyUI more comfortable."
-version = "1.0.2512060053"
+version = "1.0.2512071717"
 license = { file = "LICENSE" }
 dependencies = []
 
diff --git a/src_web/comfyui/testing/runner.ts b/src_web/comfyui/testing/runner.ts
index 0be2023..0e9a4db 100644
--- a/src_web/comfyui/testing/runner.ts
+++ b/src_web/comfyui/testing/runner.ts
@@ -86,6 +86,7 @@ function log(msg: string, styles: string) {
 class Expectation {
   private propertyLabel: string | null = "";
   private expectedLabel: string | null = "";
+  private verbLabel: string | null = "be";
   private expectedFn!: (v: any) => boolean;
   private value: any;
 
@@ -124,9 +125,17 @@ class Expectation {
     this.expectedLabel = "a number";
     return this.toBeEval();
   }
+  toContain(labelOrExpected: any, maybeExpected?: any) {
+    const expected = maybeExpected !== undefined ? maybeExpected : labelOrExpected;
+    this.propertyLabel = maybeExpected !== undefined ? labelOrExpected : null;
+    this.verbLabel = 'contain';
+    this.expectedLabel = JSON.stringify(expected);
+    this.expectedFn = (v) => v.includes(expected);
+    return this.toBeEval();
+  }
   toBeEval(strict = false) {
     let evaluation = this.expectedFn(this.value);
-    let msg = `Expected ${this.propertyLabel ? this.propertyLabel + " to be " : ""}${
+    let msg = `Expected ${this.propertyLabel ? this.propertyLabel + ` to ${this.verbLabel} ` : ""}${
       this.expectedLabel
     }`;
     msg += evaluation ? "." : `, but was ${JSON.stringify(this.value)}`;
diff --git a/src_web/comfyui/testing/utils_test.ts b/src_web/comfyui/testing/utils_test.ts
new file mode 100644
index 0000000..9c805f2
--- /dev/null
+++ b/src_web/comfyui/testing/utils_test.ts
@@ -0,0 +1,41 @@
+import type {LGraphNode} from "@comfyorg/frontend";
+import type {ComfyUITestEnvironment} from "./comfyui_env";
+
+export const PNG_1x1 =
+  "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVQIW2P4v5ThPwAG7wKklwQ/bwAAAABJRU5ErkJggg==";
+export const PNG_1x2 =
+  "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAACCAYAAACZgbYnAAAAEElEQVQIW2NgYGD4D8QM/wEHAwH/OMSHKAAAAABJRU5ErkJggg==";
+export const PNG_2x1 =
+  "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAABCAYAAAD0In+KAAAAD0lEQVQIW2NkYGD4D8QMAAUNAQFqjhCLAAAAAElFTkSuQmCC";
+
+export async function pasteImageToLoadImageNode(
+  env: ComfyUITestEnvironment,
+  dataUrl?: string,
+  node?: LGraphNode,
+) : Promise<LGraphNode> {
+  const dataArr = (dataUrl ?? PNG_1x1).split(",");
+  const mime = dataArr[0]!.match(/:(.*?);/)![1];
+  const bstr = atob(dataArr[1]!);
+  let n = bstr.length;
+  const u8arr = new Uint8Array(n);
+  while (n--) {
+    u8arr[n] = bstr.charCodeAt(n);
+  }
+  const filename = `test_image_${+new Date()}.png`;
+  const file = new File([u8arr], filename, {type: mime});
+  if (!node) {
+    node = await env.addNode("LoadImage");
+  }
+  await (node as any).pasteFiles([file]);
+  let i = 0;
+  let good = false;
+  while (i++ < 10 || good) {
+    good = node.widgets![0]!.value === filename;
+    if (good) break;
+    await env.wait(100);
+  }
+  if (!good) {
+    throw new Error("Expected file not loaded.");
+  }
+  return node;
+}
diff --git a/src_web/comfyui/tests/image_or_latent_size_tests.ts b/src_web/comfyui/tests/image_or_latent_size_tests.ts
index 3c35972..0cb932b 100644
--- a/src_web/comfyui/tests/image_or_latent_size_tests.ts
+++ b/src_web/comfyui/tests/image_or_latent_size_tests.ts
@@ -3,41 +3,10 @@ import type {LGraphNode} from "@comfyorg/frontend";
 import {NodeTypesString} from "../constants";
 import {ComfyUITestEnvironment} from "../testing/comfyui_env";
 import {describe, should, beforeEach, expect, describeRun} from "../testing/runner.js";
+import {pasteImageToLoadImageNode, PNG_1x1, PNG_1x2, PNG_2x1} from "../testing/utils_test.js";
 
 const env = new ComfyUITestEnvironment();
 
-const PNG_1x1 =
-  "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVQIW2P4v5ThPwAG7wKklwQ/bwAAAABJRU5ErkJggg==";
-const PNG_1x2 =
-  "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAACCAYAAACZgbYnAAAAEElEQVQIW2NgYGD4D8QM/wEHAwH/OMSHKAAAAABJRU5ErkJggg==";
-const PNG_2x1 =
-  "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAIAAAABCAYAAAD0In+KAAAAD0lEQVQIW2NkYGD4D8QMAAUNAQFqjhCLAAAAAElFTkSuQmCC";
-
-async function pastImageToLoadImgeNode(dataUrl: string, node: LGraphNode) {
-  const dataArr = dataUrl.split(",");
-  const mime = dataArr[0]!.match(/:(.*?);/)![1];
-  const bstr = atob(dataArr[1]!);
-  let n = bstr.length;
-  const u8arr = new Uint8Array(n);
-  while (n--) {
-    u8arr[n] = bstr.charCodeAt(n);
-  }
-  const filename = `test_image_${+new Date()}.png`;
-  const file = new File([u8arr], filename, {type: mime});
-  await (node as any).pasteFiles([file]);
-  let i = 0;
-  let good = false;
-  while (i++ < 10 || good) {
-    good = node.widgets![0]!.value === filename;
-    if (good) break;
-    await env.wait(100);
-  }
-  if (!good) {
-    throw new Error("Expected file not loaded.");
-  }
-  return node;
-}
-
 describe("TestImageOrLatentSize", async () => {
   await beforeEach(async () => {
     await env.clear();
@@ -61,21 +30,21 @@ describe("TestImageOrLatentSize", async () => {
     });
 
     await should("get correct size for a 1x1 image", async () => {
-      await pastImageToLoadImgeNode(PNG_1x1, imageNode);
+      await pasteImageToLoadImageNode(env, PNG_1x1, imageNode);
       await env.queuePrompt();
       expect(displayAnyW.widgets![0]!.value).toBe("width", 1);
       expect(displayAnyH.widgets![0]!.value).toBe("height", 1);
     });
 
     await should("get correct size for a 1x2 image", async () => {
-      await pastImageToLoadImgeNode(PNG_1x2, imageNode);
+      await pasteImageToLoadImageNode(env, PNG_1x2, imageNode);
       await env.queuePrompt();
       expect(displayAnyW.widgets![0]!.value).toBe("width", 1);
       expect(displayAnyH.widgets![0]!.value).toBe("height", 2);
     });
 
     await should("get correct size for a 2x1 image", async () => {
-      await pastImageToLoadImgeNode(PNG_2x1, imageNode);
+      await pasteImageToLoadImageNode(env, PNG_2x1, imageNode);
       await env.queuePrompt();
       expect(displayAnyW.widgets![0]!.value).toBe("width", 2);
       expect(displayAnyH.widgets![0]!.value).toBe("height", 1);
diff --git a/src_web/comfyui/tests/power_puter.ts b/src_web/comfyui/tests/power_puter.ts
index 2edf0ff..165f977 100644
--- a/src_web/comfyui/tests/power_puter.ts
+++ b/src_web/comfyui/tests/power_puter.ts
@@ -3,16 +3,17 @@ import type {LGraphNode} from "@comfyorg/frontend";
 import {NodeTypesString} from "../constants";
 import {ComfyUITestEnvironment} from "../testing/comfyui_env";
 import {describe, should, beforeEach, expect, describeRun} from "../testing/runner.js";
+import {pasteImageToLoadImageNode, PNG_1x1, PNG_1x2, PNG_2x1} from "../testing/utils_test.js";
 
 const env = new ComfyUITestEnvironment();
 
 function setPowerPuterValue(node: LGraphNode, outputType: string, value: string) {
   // Strip as much whitespace on first non-empty line from all lines.
-  if (value.includes('\n')) {
-    value = value.replace(/^\n/gm, '')
+  if (value.includes("\n")) {
+    value = value.replace(/^\n/gm, "");
     const strip = value.match(/^(.*?)\S/)?.[1]?.length;
     if (strip) {
-      value = value.replace(new RegExp(`^.{${strip}}`, 'mg'), '')
+      value = value.replace(new RegExp(`^.{${strip}}`, "mg"), "");
     }
   }
   node.widgets![1]!.value = value;
@@ -107,4 +108,23 @@ describe("TestPowerPuter", async () => {
     await env.queuePrompt();
     expect(displayAny.widgets![0]!.value).toBe("(4, 2, 0)");
   });
+
+  await should("disallow calls to some methods", async () => {
+    const imageNode = await pasteImageToLoadImageNode(env);
+    imageNode.connect(0, powerPuter, 0);
+    setPowerPuterValue(
+      powerPuter,
+      "STRING",
+      `a.numpy().tofile('/tmp/test')
+      `,
+    );
+    await env.queuePrompt();
+
+    // Check to see if there's an error.
+    expect(document.querySelector(".p-dialog-mask .p-card-body")!.textContent).toContain(
+      "error message",
+      "Disallowed access to \"tofile\" for type <class 'numpy.ndarray'>",
+    );
+    (document.querySelector(".p-dialog-mask .p-dialog-close-button")! as HTMLButtonElement).click();
+  });
 });