Allow the use of libraries in macro definitions (#3803)

* Allow the use of libraries in macro definitions

* Move library usage in macro test to separate test case

src/sqlfluff/core/templaters/jinja.py

@@ -286,6 +286,10 @@ def get_context(self, fname=None, config=None, **kw) -> Dict:
         live_context = super().get_context(fname=fname, config=config)
         # Apply dbt builtin functions if we're allowed.
         if config:
+            # first make libraries available in the context
+            # so they can be used by the macros too
+            live_context.update(self._extract_libraries_from_config(config=config))
+
             apply_dbt_builtins = config.get_section(
                 (self.templater_selector, self.name, "apply_dbt_builtins")
             )
@@ -316,7 +320,6 @@ def get_context(self, fname=None, config=None, **kw) -> Dict:
                 )
             )
 
-            live_context.update(self._extract_libraries_from_config(config=config))
         return live_context
 
     def template_builder(

test/fixtures/templater/jinja_r_library_in_macro/jinja.sql

@@ -0,0 +1 @@
+{{ query_proxy('xyz') }}

test/fixtures/templater/jinja_r_library_in_macro/jinja.yml

@@ -0,0 +1,24 @@
+file:
+  statement:
+    select_statement:
+      select_clause:
+        keyword: SELECT
+        select_clause_element:
+          numeric_literal: '56'
+      from_clause:
+        keyword: FROM
+        from_expression:
+          from_expression_element:
+            table_expression:
+              table_reference:
+              - naked_identifier: sch1
+              - dot: .
+              - naked_identifier: foo_xyz
+      where_clause:
+        keyword: WHERE
+        expression:
+          column_reference:
+            naked_identifier: x
+          comparison_operator:
+            raw_comparison_operator: '='
+          numeric_literal: '23'

test/fixtures/templater/jinja_r_library_in_macro/libs/bar.py

@@ -0,0 +1,6 @@
+"""Module used to test bar within the jinja template."""
+
+
+def equals(col, val):
+    """Return a string that has col = val."""
+    return f"{col} = {val}"

test/fixtures/templater/jinja_r_library_in_macro/libs/foo.py

@@ -0,0 +1,7 @@
+"""Module used to test foo within the jinja template."""
+schema = "sch1"
+
+
+def table(name):
+    """Return the parameter with foo_ in front of it."""
+    return f"foo_{name}"

test/fixtures/templater/jinja_r_library_in_macro/libs/not_python.txt

@@ -0,0 +1 @@
+I am just a text file

test/fixtures/templater/jinja_r_library_in_macro/macros/query_proxy.sql

@@ -0,0 +1,4 @@
+{% macro query_proxy(tbl) %}SELECT 56
+FROM {{ foo.schema }}.{{ foo.bar("xyz") }}
+WHERE {{ bar.equals("x", 23) }}
+{% endmacro %}