From d21bd8240631335e5d630b94c011de47f7614ea9 Mon Sep 17 00:00:00 2001
From: Darren Burns <darrenb900@gmail.com>
Date: Thu, 3 Feb 2022 10:27:01 +0000
Subject: [PATCH] Adding a test around the whitespace trimming logic

---
 src/textual/css/parse.py |  3 ++-
 tests/css/test_parse.py  | 17 +++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/textual/css/parse.py b/src/textual/css/parse.py
index 0ef63547c..89e74228e 100644
--- a/src/textual/css/parse.py
+++ b/src/textual/css/parse.py
@@ -242,7 +242,8 @@ def substitute_references(tokens: Iterator[Token]) -> Iterable[Token]:
             variable_name = token.value[1:-1]  # Trim the $ and the :, i.e. "$x:" -> "x"
             yield token
 
-            # Lookahead for the variable value tokens
+            # Store the tokens for any variable definitions, and substitute
+            # any variable references we encounter with them.
             leading_whitespace = True
             while True:
                 token = next(tokens, None)
diff --git a/tests/css/test_parse.py b/tests/css/test_parse.py
index a08882f5f..79c0ff7e5 100644
--- a/tests/css/test_parse.py
+++ b/tests/css/test_parse.py
@@ -30,6 +30,23 @@ class TestVariableReferenceSubstitution:
             Token(name='declaration_set_end', value='}', path='', code=css, location=(0, 31))
         ]
 
+    def test_simple_reference_no_whitespace(self):
+        css = "$x:1; #some-widget{border: $x;}"
+        variables = substitute_references(tokenize(css, ""))
+        assert list(variables) == [
+            Token(name='variable_name', value='$x:', path='', code=css, location=(0, 0)),
+            Token(name='number', value='1', path='', code=css, location=(0, 3)),
+            Token(name='variable_value_end', value=';', path='', code=css, location=(0, 4)),
+            Token(name='whitespace', value=' ', path='', code=css, location=(0, 5)),
+            Token(name='selector_start_id', value='#some-widget', path='', code=css, location=(0, 6)),
+            Token(name='declaration_set_start', value='{', path='', code=css, location=(0, 18)),
+            Token(name='declaration_name', value='border:', path='', code=css, location=(0, 19)),
+            Token(name='whitespace', value=' ', path='', code=css, location=(0, 26)),
+            Token(name='number', value='1', path='', code=css, location=(0, 3)),
+            Token(name='declaration_end', value=';', path='', code=css, location=(0, 29)),
+            Token(name='declaration_set_end', value='}', path='', code=css, location=(0, 30))
+        ]
+
     def test_undefined_variable(self):
         css = ".thing { border: $not-defined; }"
         with pytest.raises(UnresolvedVariableError):