Trim trailing lines

Author: JordonPhillips

smithy-docgen-core/src/main/java/software/amazon/smithy/docgen/core/writers/MarkdownWriter.java

@@ -42,4 +42,10 @@ public DocWriter openHeading(String content, int level) {
         writeWithNewline(StringUtils.repeat("#", level) + " " + content);
         return this;
     }
+
+    @Override
+    public String toString() {
+        // Ensure there's exactly one trailing newline
+        return super.toString().stripTrailing() + "\n";
+    }
 }

smithy-docgen-core/src/test/java/software/amazon/smithy/docgen/core/SmithyDocPluginTest.java

@@ -56,9 +56,10 @@ public void assertDocumentationFiles() {
     }
 
     private void assertServicePageContents(MockManifest manifest) {
-        String servicePage = manifest.expectFileString("/content/SampleService.md");
+        var actual = manifest.expectFileString("/content/SampleService.md");
+        var expected = readExpectedPageContent("expected-outputs/SampleService.md");
 
-        assertEquals(servicePage, readExpectedPageContent("expected-outputs/SampleService.md"));
+        assertEquals(expected, actual);
     }
 
     private String readExpectedPageContent(String filename) {

smithy-docgen-core/src/test/resources/software/amazon/smithy/docgen/core/expected-outputs/SampleService.md

@@ -3,5 +3,3 @@
 <p> This paragraph contains documentation about Sample Service. Sample Service is defined in the Smithy IDL.
     For more information about Smithy IDL see
     <a href="https://smithy.io/2.0/index.html">Smithy documentation</a>.</p>
-
-