Fixed Long discussion post not rendering Latex expressions

TNL-1902

common/templates/mathjax_include.html

@@ -12,7 +12,6 @@
     tex2jax: {inlineMath: [ ['$','$'], ["\\(","\\)"]],
               displayMath: [ ['$$','$$'], ["\\[","\\]"]]}
   });
-  HUB = MathJax.Hub
 </script>
 %else:
 <script type="text/x-mathjax-config">
@@ -28,7 +27,6 @@
       ]
     }
   });
-  HUB = MathJax.Hub
 </script>
 %endif
 

common/test/acceptance/pages/lms/discussion.py

@@ -112,6 +112,16 @@ class DiscussionThreadPage(PageObject, DiscussionPageMixin):
         """Returns true if the response editor is present, false otherwise"""
         return self._is_element_visible(".response_{} .edit-post-body".format(response_id))
 
+    @wait_for_js
+    def is_discussion_body_visible(self):
+        return self._is_element_visible(".post-body")
+
+    def is_mathjax_preview_available(self):
+        return self.q(css=".MathJax_Preview").text[0] == ""
+
+    def is_mathjax_rendered(self):
+        return self._is_element_visible(".MathJax")
+
     def is_response_visible(self, comment_id):
         """Returns true if the response is viewable onscreen"""
         return self._is_element_visible(".response_{} .response-body".format(comment_id))

common/test/acceptance/tests/discussion/test_discussion.py

@@ -33,6 +33,68 @@ from ...fixtures.discussion import (
 from .helpers import BaseDiscussionMixin
 
 
+THREAD_CONTENT_WITH_LATEX = """Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur.
+                               \n\n----------\n\nLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur. (b).\n\n
+                               **(a)** $H_1(e^{j\\omega}) = \\sum_{n=-\\infty}^{\\infty}h_1[n]e^{-j\\omega n} =
+                               \\sum_{n=-\\infty} ^{\\infty}h[n]e^{-j\\omega n}+\\delta_2e^{-j\\omega n_0}$
+                               $= H(e^{j\\omega})+\\delta_2e^{-j\\omega n_0}=A_e (e^{j\\omega}) e^{-j\\omega n_0}
+                               +\\delta_2e^{-j\\omega n_0}=e^{-j\\omega n_0} (A_e(e^{j\\omega})+\\delta_2)
+                               $H_3(e^{j\\omega})=A_e(e^{j\\omega})+\\delta_2$. Dummy $A_e(e^{j\\omega})$ dummy post $.
+                               $A_e(e^{j\\omega}) \\ge -\\delta_2$, it follows that $H_3(e^{j\\omega})$ is real and
+                               $H_3(e^{j\\omega})\\ge 0$.\n\n**(b)** Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur.\n\n
+                               **Case 1:** If $re^{j\\theta}$ is a Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur.
+                               \n\n**Case 3:** Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur.
+                               Lorem $H_3(e^{j\\omega}) = P(cos\\omega)(cos\\omega - cos\\theta)^k$,
+                               Lorem Lorem Lorem Lorem Lorem Lorem $P(cos\\omega)$ has no
+                               $(cos\\omega - cos\\theta)$ factor.
+                               Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur.
+                               $P(cos\\theta) \\neq 0$. Since $P(cos\\omega)$ this is a dummy data post $\\omega$,
+                               dummy $\\delta > 0$ such that for all $\\omega$ dummy $|\\omega - \\theta|
+                               < \\delta$, $P(cos\\omega)$ Lorem ipsum dolor sit amet, consectetur adipiscing elit,
+                               sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim
+                               veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
+                               consequat. Duis aute irure dolor in reprehenderit in voluptate velit sse cillum dolore
+                               Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur.
+                               Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur.
+                               Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur.
+                               Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur.
+                               Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt
+                               ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+                               ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+                               reprehenderit in voluptate velit sse cillum dolore eu fugiat nulla pariatur.
+                               """
+
+
 class DiscussionResponsePaginationTestMixin(BaseDiscussionMixin):
     """
     A mixin containing tests for response pagination for use by both inline
@@ -153,6 +215,23 @@ class DiscussionTabSingleThreadTest(BaseDiscussionTestCase, DiscussionResponsePa
         self.thread_page = self.create_single_thread_page(thread_id)  # pylint: disable=attribute-defined-outside-init
         self.thread_page.visit()
 
+    def test_mathjax_rendering(self):
+        thread_id = "test_thread_{}".format(uuid4().hex)
+
+        thread_fixture = SingleThreadViewFixture(
+            Thread(
+                id=thread_id,
+                body=THREAD_CONTENT_WITH_LATEX,
+                commentable_id=self.discussion_id,
+                thread_type="discussion"
+            )
+        )
+        thread_fixture.push()
+        self.setup_thread_page(thread_id)
+        self.assertTrue(self.thread_page.is_discussion_body_visible())
+        self.assertTrue(self.thread_page.is_mathjax_preview_available())
+        self.assertTrue(self.thread_page.is_mathjax_rendered())
+
     def test_marked_answer_comments(self):
         thread_id = "test_thread_{}".format(uuid4().hex)
         response_id = "test_response_{}".format(uuid4().hex)

lms/static/coffee/src/customwmd.coffee

@@ -31,7 +31,7 @@ $ ->
       block = @blocks.slice(start, last + 1).join("").replace(/&/g, "&")
                                                     .replace(/</g, "&lt;")
                                                     .replace(/>/g, "&gt;")
-      if HUB.Browser.isMSIE
+      if MathJax.Hub.Browser.isMSIE
         block = block.replace /(%[^\n]*)\n/g, "$1<br/>\n"
       @blocks[i] = "" for i in [start+1..last]
       @blocks[start] = "@@#{@math.length}@@"