test: 🚨 add spec for prime checking

Author: maxbarsukov

spec/largest_prime_factor/concerns/prime_spec.exs

@@ -0,0 +1,27 @@
+defmodule LargestPrimeFactor.Concerns.PrimeSpec do
+  @moduledoc "Testing Prime checker concern"
+
+  use LargestPrimeFactor.Concerns.Prime
+  use ESpec, async: true
+
+  describe "checking is number prime" do
+    it "detects prime numbers" do
+      expect prime?(2) |> to(be_true())
+      expect prime?(3) |> to(be_true())
+      expect prime?(5) |> to(be_true())
+      expect prime?(11) |> to(be_true())
+      expect prime?(11_159) |> to(be_true())
+      expect prime?(99_018_119) |> to(be_true())
+      expect prime?(99_016_915_337) |> to(be_true())
+      expect prime?(123_142_416_451) |> to(be_true())
+      expect prime?(999_999_995_017) |> to(be_true())
+    end
+
+    it "detects non-prime numbers" do
+      expect prime?(1) |> to(be_false())
+      expect prime?(4) |> to(be_false())
+      expect prime?(51) |> to(be_false())
+      expect prime?(999_999_995_018) |> to(be_false())
+    end
+  end
+end