diff --git a/test/integration/testing/commonjs.test.js b/test/integration/testing/commonjs.test.js
index 707c73b92..a0576fd24 100644
--- a/test/integration/testing/commonjs.test.js
+++ b/test/integration/testing/commonjs.test.js
@@ -45,11 +45,24 @@ testProp(
   "Stubscape#quote (esm === cjs)",
   [arbitrary.shescapeArg(), arbitrary.shescapeOptions()],
   (t, arg, options) => {
+    let resultEsm, resultCjs, erroredEsm, erroredCjs;
+
     const stubscape = new Stubscape(options);
     const stubscapeCjs = new StubscapeCjs(options);
 
-    const resultEsm = stubscape.quote(arg);
-    const resultCjs = stubscapeCjs.quote(arg);
+    try {
+      resultEsm = stubscape.quote(arg);
+    } catch (_) {
+      erroredEsm = true;
+    }
+
+    try {
+      resultCjs = stubscapeCjs.quote(arg);
+    } catch (_) {
+      erroredCjs = true;
+    }
+
+    t.is(erroredEsm, erroredCjs);
     t.is(resultEsm, resultCjs);
   },
 );
@@ -58,11 +71,24 @@ testProp(
   "Stubscape#quoteAll (esm === cjs)",
   [fc.array(arbitrary.shescapeArg()), arbitrary.shescapeOptions()],
   (t, args, options) => {
+    let resultEsm, resultCjs, erroredEsm, erroredCjs;
+
     const stubscape = new Stubscape(options);
     const stubscapeCjs = new StubscapeCjs(options);
 
-    const resultEsm = stubscape.quoteAll(args);
-    const resultCjs = stubscapeCjs.quoteAll(args);
+    try {
+      resultEsm = stubscape.quoteAll(args);
+    } catch (_) {
+      erroredEsm = true;
+    }
+
+    try {
+      resultCjs = stubscapeCjs.quoteAll(args);
+    } catch (_) {
+      erroredCjs = true;
+    }
+
+    t.is(erroredEsm, erroredCjs);
     t.deepEqual(resultEsm, resultCjs);
   },
 );
diff --git a/test/integration/testing/functional.test.js b/test/integration/testing/functional.test.js
index f307b3323..ec84f75db 100644
--- a/test/integration/testing/functional.test.js
+++ b/test/integration/testing/functional.test.js
@@ -78,10 +78,7 @@ testProp(
 
 testProp(
   "Stubscape#quote, with shell (stubscape =~ shescape)",
-  [
-    fc.anything(),
-    arbitrary.shescapeOptions().filter((options) => options?.shell !== false),
-  ],
+  [fc.anything(), arbitrary.shescapeOptions()],
   (t, arg, options) => {
     let result, stubResult, errored, stubErrored;
 
@@ -113,10 +110,7 @@ testProp(
 
 testProp(
   "Stubscape#quoteAll, with shell (stubscape =~ shescape)",
-  [
-    fc.anything(),
-    arbitrary.shescapeOptions().filter((options) => options?.shell !== false),
-  ],
+  [fc.anything(), arbitrary.shescapeOptions()],
   (t, args, options) => {
     let result, stubResult, errored, stubErrored;
 
diff --git a/test/unit/testing/stubscape.test.js b/test/unit/testing/stubscape.test.js
index 5c85ac164..d5f1bc8cf 100644
--- a/test/unit/testing/stubscape.test.js
+++ b/test/unit/testing/stubscape.test.js
@@ -68,7 +68,10 @@ test("escapeAll invalid arguments", (t) => {
 
 testProp(
   "quote valid arguments",
-  [arbitrary.shescapeArg(), arbitrary.shescapeOptions()],
+  [
+    arbitrary.shescapeArg(),
+    arbitrary.shescapeOptions().filter((options) => options?.shell !== false),
+  ],
   (t, arg, options) => {
     const stubscape = new Stubscape(options);
     const result = stubscape.quote(arg);
@@ -87,9 +90,26 @@ test("quote invalid arguments", (t) => {
   }
 });
 
+testProp(
+  "quote without a shell",
+  [
+    arbitrary.shescapeArg(),
+    arbitrary.shescapeOptions().filter((options) => options?.shell === false),
+  ],
+  (t, arg, options) => {
+    const stubscape = new Stubscape(options);
+    t.throws(() => stubscape.quote(arg), {
+      instanceOf: Error,
+    });
+  },
+);
+
 testProp(
   "quoteAll valid arguments",
-  [fc.array(arbitrary.shescapeArg()), arbitrary.shescapeOptions()],
+  [
+    fc.array(arbitrary.shescapeArg()),
+    arbitrary.shescapeOptions().filter((options) => options?.shell !== false),
+  ],
   (t, args, options) => {
     const stubscape = new Stubscape(options);
     const result = stubscape.quoteAll(args);
@@ -100,12 +120,14 @@ testProp(
 
 testProp(
   "quoteAll non-array arguments",
-  [arbitrary.shescapeArg(), arbitrary.shescapeOptions()],
+  [
+    arbitrary.shescapeArg(),
+    arbitrary.shescapeOptions().filter((options) => options?.shell !== false),
+  ],
   (t, arg, options) => {
     const stubscape = new Stubscape(options);
     t.throws(() => stubscape.quoteAll(arg), {
       instanceOf: TypeError,
-      message: "args.map is not a function",
     });
   },
 );
@@ -120,3 +142,17 @@ test("quoteAll invalid arguments", (t) => {
     });
   }
 });
+
+testProp(
+  "quoteAll without a shell",
+  [
+    fc.array(arbitrary.shescapeArg()),
+    arbitrary.shescapeOptions().filter((options) => options?.shell === false),
+  ],
+  (t, args, options) => {
+    const stubscape = new Stubscape(options);
+    t.throws(() => stubscape.quoteAll(args), {
+      instanceOf: Error,
+    });
+  },
+);
diff --git a/testing.js b/testing.js
index 97352d4bf..9e999149a 100644
--- a/testing.js
+++ b/testing.js
@@ -26,17 +26,19 @@ export const injectionStrings = [
 ];
 
 /**
- * A test stub of Shescape that has the same input-output profile as the real
- * Shescape implementation.
+ * An optimistic test stub of Shescape that has the same input-output profile as
+ * the real Shescape implementation.
  *
  * In particular:
+ * - The constructor never fails.
  * - Returns a string for all stringable inputs.
  * - Errors on non-stringable inputs.
- * - Converts non-array inputs to single-item arrays where necessary.
+ * - Errors on non-array inputs where arrays are expected.
+ * - Errors when trying to quote when `shell: false`.
  */
 export class Shescape {
-  constructor(_options) {
-    // Nothing to do.
+  constructor(options = {}) {
+    this.shell = options.shell;
   }
 
   escape(arg) {
@@ -48,10 +50,18 @@ export class Shescape {
   }
 
   quote(arg) {
+    if (this.shell === false) {
+      throw new Error();
+    }
+
     return this.escape(arg);
   }
 
   quoteAll(args) {
+    if (this.shell === false) {
+      throw new Error();
+    }
+
     return this.escapeAll(args);
   }
 }