print snippet information in backtrace (fix #551)

pythonx/UltiSnips/snippet/definition/_base.py

@@ -6,6 +6,7 @@
 import re
 
 import vim
+import textwrap
 
 from UltiSnips import _vim
 from UltiSnips.compatibility import as_unicode
@@ -116,7 +117,29 @@ class SnippetDefinition(object):
 
         snip = SnippetUtilForAction(locals)
 
-        exec(code, {'snip': snip})
+        try:
+            exec(code, {'snip': snip})
+        except Exception as e:
+            e.snippet_info = textwrap.dedent("""
+                Trigger: {}
+                Description: {}
+                Context: {}
+                Pre-expand: {}
+                Post-expand: {}
+            """).format(
+                self._trigger,
+                self._description,
+                self._context_code if self._context_code else '<none>',
+                self._actions['pre_expand'] if 'pre_expand' in self._actions
+                    else '<none>',
+                self._actions['post_expand'] if 'post_expand' in self._actions
+                    else '<none>',
+                code,
+            )
+
+            e.snippet_code = code
+
+            raise
 
         return snip
 

pythonx/UltiSnips/snippet_manager.py

@@ -10,6 +10,7 @@ import platform
 import traceback
 import sys
 import vim
+import re
 from contextlib import contextmanager
 
 from UltiSnips import _vim
@@ -68,6 +69,11 @@ Following is the full stack trace:
 """
 
             msg += traceback.format_exc()
+            if hasattr(e, 'snippet_info'):
+                msg += "\nSnippet, caused error:\n"
+                msg += re.sub(
+                    '^(?=\S)', '  ', e.snippet_info, flags=re.MULTILINE
+                )
             # snippet_code comes from _python_code.py, it's set manually for
             # providing error message with stacktrace of failed python code
             # inside of the snippet.

test/test_ParseSnippets.py

@@ -263,3 +263,44 @@ class ParseSnippets_PrintPythonStacktraceMultiline(_VimTest):
     wanted = keys
     expected_error = " > \s+qwe"
 
+
+class ParseSnippets_PrintErroneousSnippet(_VimTest):
+    files = { 'us/all.snippets': r"""
+        snippet test "asd()" e
+        endsnippet
+        """}
+    keys = 'test' + EX
+    wanted = keys
+    expected_error = "Trigger: test"
+
+
+class ParseSnippets_PrintErroneousSnippetContext(_VimTest):
+    files = { 'us/all.snippets': r"""
+        snippet test "asd()" e
+        endsnippet
+        """}
+    keys = 'test' + EX
+    wanted = keys
+    expected_error = "Context: asd"
+
+
+class ParseSnippets_PrintErroneousSnippetPreAction(_VimTest):
+    files = { 'us/all.snippets': r"""
+        pre_expand "asd()"
+        snippet test
+        endsnippet
+        """}
+    keys = 'test' + EX
+    wanted = keys
+    expected_error = "Pre-expand: asd"
+
+
+class ParseSnippets_PrintErroneousSnippetPostAction(_VimTest):
+    files = { 'us/all.snippets': r"""
+        post_expand "asd()"
+        snippet test
+        endsnippet
+        """}
+    keys = 'test' + EX
+    wanted = keys
+    expected_error = "Post-expand: asd"