Benchmark template rendering times

A concern is that rendering the template this way could be much slower,
assuming Jinja2 makes extensive use of caching. We thus write a
comparative benchmark between using Jinja2 templates or simply
concatenating strings.

pyproject.toml

@@ -20,7 +20,7 @@ packages = ["prompts"]
 write_to = "prompts/_version.py"
 
 [project.optional-dependencies]
-test = ["pre-commit", "pytest"]
+test = ["pre-commit", "pytest", "pytest-benchmark"]
 docs = [
     "mkdocs",
     "mkdocs-material",

tests/test_templates.py

@@ -1,3 +1,6 @@
+import random
+import string
+
 import pytest
 
 import prompts
@@ -192,3 +195,42 @@ def simple_prompt_name(query: str):
     assert simple_prompt("test") == "test"
     assert simple_prompt["gpt2"]("test") == "test"
     assert simple_prompt["provider/name"]("test") == "name: test"
+
+
+def test_benchmark_template_render(benchmark):
+
+    @prompts.template
+    def test_tpl(var0, var1):
+        prompt = var0
+        return prompt + """{{var1}} test"""
+
+    def setup():
+        """We generate random strings to make sure we don't hit any potential cache."""
+        length = 10
+        var0 = "".join(
+            random.choice(string.ascii_uppercase + string.digits) for _ in range(length)
+        )
+        var1 = "".join(
+            random.choice(string.ascii_uppercase + string.digits) for _ in range(length)
+        )
+        return (var0, var1), {}
+
+    benchmark.pedantic(test_tpl, setup=setup, rounds=500)
+
+
+def test_benchmark_template_function(benchmark):
+
+    def test_tpl(var0, var1):
+        return var0 + f"{var1} test"
+
+    def setup():
+        length = 10
+        var0 = "".join(
+            random.choice(string.ascii_uppercase + string.digits) for _ in range(length)
+        )
+        var1 = "".join(
+            random.choice(string.ascii_uppercase + string.digits) for _ in range(length)
+        )
+        return (var0, var1), {}
+
+    benchmark.pedantic(test_tpl, setup=setup, rounds=500)