Integration Test Optimizations (#56)

* Cache static objects between tests to accelerate integration runs.

* Formatting

* Add changelog entry.

* Remove debug print.

* Move tests module implementation.

* Tests file.

* Add method to disable test caching.

.changes/unreleased/Features-20240131-152923.yaml

@@ -0,0 +1,6 @@
+kind: Features
+body: Cache static objects between tests to accelerate integration runs.
+time: 2024-01-31T15:29:23.951857-05:00
+custom:
+  Author: peterallenwebb
+  Issue: "55"

dbt_common/clients/jinja.py

@@ -16,6 +16,7 @@
 import jinja2.parser  # type: ignore
 import jinja2.sandbox  # type: ignore
 
+from dbt_common.tests import test_caching_enabled
 from dbt_common.utils.jinja import (
     get_dbt_macro_name,
     get_docs_macro_name,
@@ -504,9 +505,19 @@ def catch_jinja(node=None) -> Iterator[None]:
         raise
 
 
+_TESTING_PARSE_CACHE: Dict[str, jinja2.Template] = {}
+
+
 def parse(string):
+    str_string = str(string)
+    if test_caching_enabled() and str_string in _TESTING_PARSE_CACHE:
+        return _TESTING_PARSE_CACHE[str_string]
+
     with catch_jinja():
-        return get_environment().parse(str(string))
+        parsed = get_environment().parse(str(string))
+        if test_caching_enabled():
+            _TESTING_PARSE_CACHE[str_string] = parsed
+        return parsed
 
 
 def get_template(
@@ -528,6 +539,15 @@ def render_template(template, ctx: Dict[str, Any], node=None) -> str:
         return template.render(ctx)
 
 
+_TESTING_BLOCKS_CACHE: Dict[int, List[Union[BlockData, BlockTag]]] = {}
+
+
+def _get_blocks_hash(text: str, allowed_blocks: Optional[Set[str]], collect_raw_data: bool) -> int:
+    """Provides a hash function over the arguments to extract_toplevel_blocks, in order to support caching."""
+    allowed_tuple = tuple(sorted(allowed_blocks) or [])
+    return text.__hash__() + allowed_tuple.__hash__() + collect_raw_data.__hash__()
+
+
 def extract_toplevel_blocks(
     text: str,
     allowed_blocks: Optional[Set[str]] = None,
@@ -537,7 +557,7 @@ def extract_toplevel_blocks(
 
     Includes some special handling for block nesting.
 
-    :param data: The data to extract blocks from.
+    :param text: The data to extract blocks from.
     :param allowed_blocks: The names of the blocks to extract from the file.
         They may not be nested within if/for blocks. If None, use the default
         values.
@@ -548,7 +568,19 @@ def extract_toplevel_blocks(
     :return: A list of `BlockTag`s matching the allowed block types and (if
         `collect_raw_data` is `True`) `BlockData` objects.
     """
+
+    if test_caching_enabled():
+        hash = _get_blocks_hash(text, allowed_blocks, collect_raw_data)
+        if hash in _TESTING_BLOCKS_CACHE:
+            return _TESTING_BLOCKS_CACHE[hash]
+
     tag_iterator = TagIterator(text)
-    return BlockIterator(tag_iterator).lex_for_blocks(
+    blocks = BlockIterator(tag_iterator).lex_for_blocks(
         allowed_blocks=allowed_blocks, collect_raw_data=collect_raw_data
     )
+
+    if test_caching_enabled():
+        hash = _get_blocks_hash(text, allowed_blocks, collect_raw_data)
+        _TESTING_BLOCKS_CACHE[hash] = blocks
+
+    return blocks

dbt_common/tests.py

@@ -0,0 +1,15 @@
+_TEST_CACHING_ENABLED: bool = False
+
+
+def test_caching_enabled() -> bool:
+    return _TEST_CACHING_ENABLED
+
+
+def enable_test_caching() -> None:
+    global _TEST_CACHING_ENABLED
+    _TEST_CACHING_ENABLED = True
+
+
+def disable_test_caching() -> None:
+    global _TEST_CACHING_ENABLED
+    _TEST_CACHING_ENABLED = False