Add test for rm_whitespace option

integration-tests/templates/rm_whitespace.out

@@ -0,0 +1,13 @@
+<div>
+<span>1</span>
+<span>2</span>
+<span>3</span>
+</div>
+<div>
+trailing spaces
+This line should be appeared under the previous line
+</div>
+<div>foo</div>
+
+<div>bar</div>
+

integration-tests/templates/rm_whitespace.stpl

@@ -0,0 +1,13 @@
+<div>
+  <span>1</span>
+  <span>2</span>
+
+  <span>3</span>
+</div>
+<div>
+  trailing spaces   
+  This line should be appeared under the previous line
+</div>
+<% for msg in messages { %>
+  <div><%= msg %></div>
+<% } %>

integration-tests/tests/basic.rs

@@ -142,6 +142,18 @@ fn test_teams() {
     assert_render("teams", teams);
 }
 
+#[derive(TemplateOnce)]
+#[template(path = "rm_whitespace.stpl")]
+#[template(rm_whitespace = true)]
+struct RmWhitespace<'a, 'b> {
+    messages: &'a [&'b str],
+}
+
+#[test]
+fn test_rm_whitespace() {
+    assert_render("rm_whitespace", RmWhitespace { messages: &["foo", "bar"] });
+}
+
 #[cfg(unix)]
 mod unix {
     use super::*;