New rule: hash duplicated key

spec/ameba/rule/hash_duplicated_key_spec.cr

@@ -0,0 +1,41 @@
+require "../../spec_helper"
+
+module Ameba::Rule
+  describe HashDuplicatedKey do
+    subject = HashDuplicatedKey.new
+
+    it "passes if there is no duplicated keys in a hash literals" do
+      s = Source.new %(
+        h = {"a" => 1, :a => 2, "b" => 3}
+        h = {"a" => 1, "b" => 2, "c" => {"a" => 3, "b" => 4}}
+        h = {} of String => String
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "fails if there is a duplicated key in a hash literal" do
+      s = Source.new %q(
+        h = {"a" => 1, "b" => 2, "a" => 3}
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "fails if there is a duplicated key in the inner hash literal" do
+      s = Source.new %q(
+        h = {"a" => 1, "b" => {"a" => 3, "b" => 4, "a" => 5}}
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "reports rule, location and message" do
+      s = Source.new %q(
+        h = {"a" => 1, "a" => 2}
+      ), "source.cr"
+      subject.catch(s).should_not be_valid
+      error = s.errors.first
+      error.rule.should_not be_nil
+      error.location.to_s.should eq "source.cr:2:13"
+      error.message.should eq "Duplicated keys in hash literal."
+    end
+  end
+end