Feature/Layout trailing lines, final newline checkup (#152)

spec/ameba/rule/layout/trailing_blank_lines_spec.cr

@@ -4,35 +4,55 @@ module Ameba::Rule::Layout
   subject = TrailingBlankLines.new
 
   describe TrailingBlankLines do
-    it "passes if there is no blank lines at the end" do
-      source = Source.new "no-blankline"
+    it "passes if there is a blank line at the end of a source" do
+      source = Source.new "a = 1\n", normalize: false
       subject.catch(source).should be_valid
     end
 
-    it "fails if there is a blank line at the end of a source" do
-      source = Source.new "a = 1\n \n ", normalize: false
-      subject.catch(source).should_not be_valid
-    end
-
     it "passes if source is empty" do
       source = Source.new ""
       subject.catch(source).should be_valid
     end
 
-    it "passes if last line is not blank" do
-      source = Source.new "\n\n\n puts 22", normalize: false
-      subject.catch(source).should be_valid
+    it "fails if there is no blank lines at the end" do
+      source = Source.new "no-blankline"
+      subject.catch(source).should_not be_valid
     end
 
-    it "reports rule, pos and message" do
-      source = Source.new "a = 1\n\n ", "source.cr", normalize: false
+    it "fails if there more then one blank line at the end of a source" do
+      source = Source.new "a = 1\n \n", normalize: false
       subject.catch(source).should_not be_valid
+    end
 
-      issue = source.issues.first
-      issue.rule.should_not be_nil
-      issue.location.to_s.should eq "source.cr:2:1"
-      issue.end_location.should be_nil
-      issue.message.should eq "Blank lines detected at the end of the file"
+    it "fails if last line is not blank" do
+      source = Source.new "\n\n\n puts 22", normalize: false
+      subject.catch(source).should_not be_valid
+    end
+
+    context "when unnecessary blank line has been detected" do
+      it "reports rule, pos and message" do
+        source = Source.new "a = 1\n\n", "source.cr", normalize: false
+        subject.catch(source).should_not be_valid
+
+        issue = source.issues.first
+        issue.rule.should_not be_nil
+        issue.location.to_s.should eq "source.cr:2:1"
+        issue.end_location.should be_nil
+        issue.message.should eq "Excessive trailing newline detected"
+      end
+    end
+
+    context "when final line has been missed" do
+      it "reports rule, pos and message" do
+        source = Source.new "a = 1", "source.cr", normalize: false
+        subject.catch(source).should_not be_valid
+
+        issue = source.issues.first
+        issue.rule.should_not be_nil
+        issue.location.to_s.should eq "source.cr:0:1"
+        issue.end_location.should be_nil
+        issue.message.should eq "Trailing newline missing"
+      end
     end
   end
 end

spec/spec_helper.cr

@@ -20,9 +20,8 @@ module Ameba
     private def normalize_source(code, separator = "\n")
       lines = code.split(separator)
 
-      # remove unneeded first and last blank lines if any
+      # remove unneeded first blank lines if any
       lines.shift if lines[0].blank? && lines.size > 1
-      lines.pop if lines[-1].blank? && lines.size > 1
 
       # find the minimum indentation
       min_indent = lines.min_of do |line|

src/ameba/rule/layout/trailing_blank_lines.cr

@@ -13,11 +13,20 @@ module Ameba::Rule::Layout
       description "Disallows trailing blank lines"
     end
 
-    MSG = "Blank lines detected at the end of the file"
+    MSG               = "Excessive trailing newline detected"
+    MSG_FINAL_NEWLINE = "Trailing newline missing"
 
     def test(source)
-      if source.lines.size > 1 && source.lines[-2, 2].join.strip.empty?
-        issue_for({source.lines.size - 1, 1}, MSG)
+      source_lines = source.lines
+      return if source_lines.empty?
+
+      last_source_line = source_lines.last
+      source_lines_size = source_lines.size
+      return if source_lines_size == 1 && last_source_line.empty?
+
+      last_line_not_empty = !last_source_line.empty?
+      if source_lines_size >= 1 && (source_lines.last(2).join.strip.empty? || last_line_not_empty)
+        issue_for({source_lines_size - 1, 1}, last_line_not_empty ? MSG_FINAL_NEWLINE : MSG)
       end
     end
   end