diff --git a/src/schemas/numberTokenSchema.test.ts b/src/schemas/numberTokenSchema.test.ts
index 9b8d83ba4..6c5074565 100644
--- a/src/schemas/numberTokenSchema.test.ts
+++ b/src/schemas/numberTokenSchema.test.ts
@@ -55,4 +55,27 @@ describe('Schema: numberToken', () => {
       }).success,
     ).toStrictEqual(false)
   })
+
+  it('fails on wrong value', () => {
+    // invalid string
+    expect(
+      numberToken.safeParse({
+        ...validToken,
+        $value: 'string',
+      }).success,
+    ).toStrictEqual(false)
+    // undefined
+    expect(
+      numberToken.safeParse({
+        ...validToken,
+        $value: undefined,
+      }).success,
+    ).toStrictEqual(false)
+    // no type
+    expect(
+      numberToken.safeParse({
+        $value: false,
+      }).success,
+    ).toStrictEqual(false)
+  })
 })
diff --git a/src/schemas/stringTokenSchema.test.ts b/src/schemas/stringTokenSchema.test.ts
new file mode 100644
index 000000000..184aa5c5a
--- /dev/null
+++ b/src/schemas/stringTokenSchema.test.ts
@@ -0,0 +1,80 @@
+import {stringToken} from './stringToken'
+
+describe('Schema: stringToken', () => {
+  const validToken = {
+    $value: 'a string',
+    $type: 'string',
+    $description: 'a string token',
+  }
+
+  it('parses valid string tokens', () => {
+    expect(stringToken.safeParse(validToken).success).toStrictEqual(true)
+  })
+
+  it('fails on invalid properties', () => {
+    // additional element
+    expect(
+      stringToken.safeParse({
+        ...validToken,
+        additional: 1000,
+      }).success,
+    ).toStrictEqual(false)
+    // missing value
+    expect(
+      stringToken.safeParse({
+        $type: 'string',
+      }).success,
+    ).toStrictEqual(false)
+    // missing type
+    expect(
+      stringToken.safeParse({
+        $value: 'a string',
+      }).success,
+    ).toStrictEqual(false)
+  })
+
+  it('fails on wrong type', () => {
+    expect(
+      stringToken.safeParse({
+        ...validToken,
+        $type: 'motion',
+      }).success,
+    ).toStrictEqual(false)
+    // undefined
+    expect(
+      stringToken.safeParse({
+        ...validToken,
+        $type: undefined,
+      }).success,
+    ).toStrictEqual(false)
+    // no type
+    expect(
+      stringToken.safeParse({
+        $value: 'a string',
+      }).success,
+    ).toStrictEqual(false)
+  })
+
+  it('fails on wrong value', () => {
+    // invalid string
+    expect(
+      stringToken.safeParse({
+        ...validToken,
+        $value: 100,
+      }).success,
+    ).toStrictEqual(false)
+    // undefined
+    expect(
+      stringToken.safeParse({
+        ...validToken,
+        $value: undefined,
+      }).success,
+    ).toStrictEqual(false)
+    // no type
+    expect(
+      stringToken.safeParse({
+        $value: false,
+      }).success,
+    ).toStrictEqual(false)
+  })
+})