diff --git a/spec/rename_spec.cr b/spec/rename_spec.cr
new file mode 100644
index 0000000..87bf302
--- /dev/null
+++ b/spec/rename_spec.cr
@@ -0,0 +1,70 @@
+require "./spec_helper"
+require "../src/rename"
+
+include Rename
+
+describe Rule do
+  it "raises on nested brackets" do
+    expect_raises Exception do
+      Rule.new "[[]]"
+    end
+    expect_raises Exception do
+      Rule.new "{{}}"
+    end
+  end
+
+  it "raises on unclosed brackets" do
+    expect_raises Exception do
+      Rule.new "["
+    end
+    expect_raises Exception do
+      Rule.new "{"
+    end
+    expect_raises Exception do
+      Rule.new "[{]}"
+    end
+  end
+
+  it "raises when closing unopened brackets" do
+    expect_raises Exception do
+      Rule.new "]"
+    end
+    expect_raises Exception do
+      Rule.new "[}"
+    end
+  end
+
+  it "handles `|` in patterns" do
+    rule = Rule.new "{a|b|c}"
+    rule.render({"b" => "b"}).should eq "b"
+    rule.render({"a" => "a", "b" => "b"}).should eq "a"
+  end
+
+  it "allows `|` outside of patterns" do
+    rule = Rule.new "hello|world"
+    rule.render({} of String => String).should eq "hello|world"
+  end
+
+  it "raises on escaped characters" do
+    expect_raises Exception do
+      Rule.new "hello/world"
+    end
+  end
+
+  it "handles spaces in patterns" do
+    rule = Rule.new "{  a }"
+    rule.render({"a" => "a"}).should eq "a"
+  end
+
+  it "strips leading and tailing spaces" do
+    rule = Rule.new "  hello "
+    rule.render({"a" => "a"}).should eq "hello"
+  end
+
+  it "renders a few examples correctly" do
+    rule = Rule.new "[Ch. {chapter }] {title | id} testing"
+    rule.render({"id" => "ID"}).should eq "ID testing"
+    rule.render({"chapter" => "CH", "id" => "ID"}).should eq "Ch. CH ID testing"
+    rule.render({} of String => String).should eq "testing"
+  end
+end