Unpack scenario root requirements in test cases (#757)

As mentioned in #746, instead of just installing the scenario root we
will unpack the root dependencies into the install command to allow
better coverage of direct user requests with scenarios.

I added display of the package tree provided by each scenario.

Use a mustache template for iterative replacements.

scripts/scenarios/generate.py

@@ -1,65 +1,35 @@
-"""
-Generates snapshot test cases from packse scenarios.
+#!/usr/bin/env python3
+#
+# Generates snapshot test cases from packse scenarios.
+#
+# Usage:
+#     $ scripts/scenarios/generate.py > crates/puffin-cli/tests/pip_install_scenarios.rs
 
-Usage:
-    $ python scripts/scenarios/generate.py > crates/puffin-cli/tests/pip_install_scenarios.rs
-"""
 try:
     import packse
 except ImportError:
     print("packse must be installed")
     exit(1)
 
+
+try:
+    import chevron_blue
+except ImportError:
+    print("chevron-blue must be installed")
+    exit(1)
+
+
 import sys
 import subprocess
 import json
+from pathlib import Path
 
+__dir__ = Path(__file__).parent
 
-TEMPLATE = """
-/// {{ name }}
-///
-/// {{ description }}
-#[test]
-fn {{ test_name }}() -> Result<()> {
-    let temp_dir = assert_fs::TempDir::new()?;
-    let cache_dir = assert_fs::TempDir::new()?;
-    let venv = create_venv_py312(&temp_dir, &cache_dir);
+TEMPLATE = __dir__ / "template.mustache"
+DATA = __dir__ / "data.json"
 
-    insta::with_settings!({
-        filters => INSTA_FILTERS.to_vec()
-    }, {
-        assert_cmd_snapshot!(Command::new(get_cargo_bin(BIN_NAME))
-            .arg("pip-install")
-            .arg("{{ prefix }}")
-            .arg("--extra-index-url")
-            .arg("https://test.pypi.org/simple")
-            .arg("--cache-dir")
-            .arg(cache_dir.path())
-            .env("VIRTUAL_ENV", venv.as_os_str())
-            .current_dir(&temp_dir), @r###"<snapshot>
-        "###);
-    });
-
-    Ok(())
-}
-"""
-
-PRELUDE = """
-#![cfg(all(feature = "python", feature = "pypi"))]
-/// Generated by `{{ generated_by }}`
-
-use std::process::Command;
-
-use anyhow::Result;
-use insta_cmd::_macro_support::insta;
-use insta_cmd::{assert_cmd_snapshot, get_cargo_bin};
-
-use common::{create_venv_py312, BIN_NAME, INSTA_FILTERS};
-
-mod common;
-"""
-
-scenarios = json.loads(
+data = json.loads(
     subprocess.check_output(
         [
             "packse",
@@ -67,20 +37,20 @@ scenarios = json.loads(
             str(packse.__development_base_path__ / "scenarios"),
         ],
     )
-)["scenarios"]
+)
 
-output = PRELUDE.lstrip().replace("{{ generated_by }}", " ".join(sys.argv))
+# Add a generated
+data["generated_by"] = f"Generated by `{' '.join(sys.argv)}`"
 
-for scenario in scenarios:
-    # Skip the example scenario file
+# Add normalized names for tests
+for scenario in data["scenarios"]:
+    scenario["normalized_name"] = scenario["name"].replace("-", "_")
+
+# Drop the example scenario
+for index, scenario in enumerate(data["scenarios"]):
     if scenario["name"] == "example":
-        continue
+        data["scenarios"].pop(index)
 
-    output += (
-        TEMPLATE.replace("{{ name }}", scenario["name"])
-        .replace("{{ test_name }}", scenario["name"].replace("-", "_"))
-        .replace("{{ description }}", scenario["description"])
-        .replace("{{ prefix }}", scenario["prefix"])
-    )
+output = chevron_blue.render(template=TEMPLATE.read_text(), data=data, no_escape=True)
 
 print(output)

scripts/scenarios/template.mustache

@@ -0,0 +1,50 @@
+
+#![cfg(all(feature = "python", feature = "pypi"))]
+
+/// {{generated_by}}
+
+use std::process::Command;
+
+use anyhow::Result;
+use insta_cmd::_macro_support::insta;
+use insta_cmd::{assert_cmd_snapshot, get_cargo_bin};
+
+use common::{create_venv_py312, BIN_NAME, INSTA_FILTERS};
+
+mod common;
+{{#scenarios}}
+
+/// {{name}}
+///
+/// {{description}}
+///
+/// {{prefix}}
+{{#tree}}
+/// {{.}}
+{{/tree}}
+#[test]
+fn {{normalized_name}}() -> Result<()> {
+    let temp_dir = assert_fs::TempDir::new()?;
+    let cache_dir = assert_fs::TempDir::new()?;
+    let venv = create_venv_py312(&temp_dir, &cache_dir);
+
+    insta::with_settings!({
+        filters => INSTA_FILTERS.to_vec()
+    }, {
+        assert_cmd_snapshot!(Command::new(get_cargo_bin(BIN_NAME))
+            .arg("pip-install")
+            {{#root.requires}}
+            .arg("{{prefix}}-{{.}}")
+            {{/root.requires}}
+            .arg("--extra-index-url")
+            .arg("https://test.pypi.org/simple")
+            .arg("--cache-dir")
+            .arg(cache_dir.path())
+            .env("VIRTUAL_ENV", venv.as_os_str())
+            .current_dir(&temp_dir), @r###"<snapshot>
+        "###);
+    });
+
+    Ok(())
+}
+{{/scenarios}}