fix email check

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    umbrellio-utils (1.5.1)
+    umbrellio-utils (1.5.2)
       memery (~> 1)
 
 GEM

spec/umbrellio_utils/checks_spec.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+describe UmbrellioUtils::Checks do
+  describe "#valid_email?" do
+    subject(:result) { described_class.valid_email?(input ) }
+    let(:input) { "user@example.com" }
+
+    it { is_expected.to eq(true) }
+
+    context "invalid input" do
+      let(:input) { "invalid" }
+
+      it { is_expected.to eq(false) }
+    end
+
+    context "input with subdomains and digits" do
+      let(:input) { "user@one.two42.ro" }
+
+      it { is_expected.to eq(true) }
+    end
+
+    context "non-string input" do
+      let(:input) { 123 }
+
+      it { is_expected.to eq(false) }
+    end
+  end
+end