1 files changed, 21 insertions, 16 deletions
diff --git a/remote/webdriver-bidi/modules/root/session.sys.mjs b/remote/webdriver-bidi/modules/root/session.sys.mjs
index a34ca514e3..8ecf7d7724 100644
--- a/remote/webdriver-bidi/modules/root/session.sys.mjs
+++ b/remote/webdriver-bidi/modules/root/session.sys.mjs
@@ -76,16 +76,10 @@ class SessionModule extends Module {
     const { events, contexts: contextIds = null } = params;
 
     // Check input types until we run schema validation.
-    lazy.assert.array(events, "events: array value expected");
-    events.forEach(name => {
-      lazy.assert.string(name, `${name}: string value expected`);
-    });
+    this.#assertNonEmptyArrayWithStrings(events, "events");
 
     if (contextIds !== null) {
-      lazy.assert.array(contextIds, "contexts: array value expected");
-      contextIds.forEach(contextId => {
-        lazy.assert.string(contextId, `${contextId}: string value expected`);
-      });
+      this.#assertNonEmptyArrayWithStrings(contextIds, "contexts");
     }
 
     const listeners = this.#updateEventMap(events, contextIds, true);
@@ -113,15 +107,9 @@ class SessionModule extends Module {
     const { events, contexts: contextIds = null } = params;
 
     // Check input types until we run schema validation.
-    lazy.assert.array(events, "events: array value expected");
-    events.forEach(name => {
-      lazy.assert.string(name, `${name}: string value expected`);
-    });
+    this.#assertNonEmptyArrayWithStrings(events, "events");
     if (contextIds !== null) {
-      lazy.assert.array(contextIds, "contexts: array value expected");
-      contextIds.forEach(contextId => {
-        lazy.assert.string(contextId, `${contextId}: string value expected`);
-      });
+      this.#assertNonEmptyArrayWithStrings(contextIds, "contexts");
     }
 
     const listeners = this.#updateEventMap(events, contextIds, false);
@@ -139,6 +127,23 @@ class SessionModule extends Module {
     }
   }
 
+  #assertNonEmptyArrayWithStrings(array, variableName) {
+    lazy.assert.array(
+      array,
+      `Expected "${variableName}" to be an array, got ${array}`
+    );
+    lazy.assert.that(
+      array => !!array.length,
+      `Expected "${variableName}" array to have at least one item`
+    )(array);
+    array.forEach(item => {
+      lazy.assert.string(
+        item,
+        `Expected elements of "${variableName}" to be a string, got ${item}`
+      );
+    });
+  }
+
   #getBrowserIdForContextId(contextId) {
     const context = lazy.TabManager.getBrowsingContextById(contextId);
     if (!context) {