New rule: trailing whitespace

spec/ameba/rules/trailing_whitespace_spec.cr

@@ -0,0 +1,27 @@
+require "../../spec_helper"
+
+module Ameba::Rules
+  subject = TrailingWhitespace.new
+
+  describe TrailingWhitespace do
+    it "passes if all lines do not have trailing whitespace" do
+      source = Source.new "", "no-whispace"
+      subject.catch(source).valid?.should be_true
+    end
+
+    it "fails if there is a line with trailing whitespace" do
+      source = Source.new "", "whitespace at the end "
+      subject.catch(source).valid?.should be_false
+    end
+
+    it "reports rule, pos and message" do
+      source = Source.new "", "a = 1\n b = 2 "
+      subject.catch(source).valid?.should be_false
+
+      error = source.errors.first
+      error.rule.should_not be_nil
+      error.pos.should eq 2
+      error.message.should eq "Trailing whitespace detected"
+    end
+  end
+end