Extract static string when parse_template_string is set

The Javascript extractor currently does not extract static strings
defined in template string quotes, if the `parse_template_string` option
is enabled.

This commit fixes that so static template strings are also extracted.

babel/messages/extract.py

@@ -785,7 +785,10 @@ def extract_javascript(
             and (not last_token or last_token.type != 'name' or last_token.value not in keywords)
             and token.type == 'template_string'
         ):
-            yield from parse_template_string(token.value, keywords, comment_tags, options, token.lineno)
+            keyword = ""
+            if function_stack and function_stack[-1].function_name in keywords:
+                keyword = function_stack[-1].function_name
+            yield from parse_template_string(token.value, keywords, comment_tags, options, token.lineno, keyword)
 
         elif token.type == 'operator' and token.value == '(':
             if last_token.type == 'name':
@@ -904,6 +907,7 @@ def parse_template_string(
     comment_tags: Collection[str],
     options: _JSOptions,
     lineno: int = 1,
+    keyword: str = "",
 ) -> Generator[_ExtractionResult, None, None]:
     """Parse JavaScript template string.
 
@@ -925,10 +929,12 @@ def parse_template_string(
             inside_str = character
         elif inside_str == character and prev_character != r'\\':
             inside_str = False
-        if level:
+        if level or keyword:
             expression_contents += character
         if not inside_str:
             if character == '{' and prev_character == '$':
+                if keyword:
+                    break
                 level += 1
             elif level and character == '}':
                 level -= 1
@@ -939,6 +945,8 @@ def parse_template_string(
                     lineno += len(line_re.findall(expression_contents))
                     expression_contents = ''
         prev_character = character
+    if keyword:
+        yield (lineno, keyword, expression_contents, [])
 
 
 _BUILTIN_EXTRACTORS = {

tests/messages/test_js_extract.py

@@ -144,6 +144,14 @@ def test_template_string_standard_usage():
 
     assert messages == [(1, 'Very template, wow', [], None)]
 
+def test_template_string_static_usage():
+    buf = BytesIO(b"msg1 = gettext(`Very template, wow`)")
+    messages = list(
+        extract.extract('javascript', buf, {"gettext": None}, [], {'parse_template_string': True}),
+    )
+
+    assert messages == [(1, 'Very template, wow', [], None)]
+
 
 def test_template_string_tag_usage():
     buf = BytesIO(b"function() { if(foo) msg1 = i18n`Tag template, wow`; }")