Update test assertions after lifecycle output change (#408)

edmorley · web-flow · commit 79427508a286 · 2025-08-14T17:42:38.000+01:00
`lifecycle` now emits all buildpack output to stdout in order to fix this stdout/stderr output interleaving bug: buildpacks/pack#2330 buildpacks/lifecycle#1525 As such, the `libcnb-test` integration test assertions need updating to use stdout in a number of places. This also allows the test assertions to correctly assert the placement of warning in-between other non-warning content. (And in the process has revealed a couple of places where whitespace could be tweaked, which will be handled separately as part of the future build output style change work). GUS-W-19337364.
diff --git a/tests/checks_test.rs b/tests/checks_test.rs
@@ -11,14 +11,16 @@ fn checks_reject_pythonhome_env_var() {
 
     TestRunner::default().build(config, |context| {
         assert_contains!(
-            context.pack_stderr,
+            context.pack_stdout,
             indoc! {"
                 [Error: Unsafe environment variable found]
                 The environment variable 'PYTHONHOME' is set, however, it can
                 cause problems with the build so we do not allow using it.
 
                 You must unset that environment variable. If you didn't set it
                 yourself, check that it wasn't set by an earlier buildpack.
+
+                ERROR: failed to build: exit status 1
             "}
         );
     });
diff --git a/tests/django_test.rs b/tests/django_test.rs
@@ -34,7 +34,7 @@ fn django_staticfiles_legacy_django() {
     TestRunner::default().build(
         default_build_config("tests/fixtures/django_staticfiles_legacy_django"),
         |context| {
-            // We can't `assert_empty!(context.pack_stderr)` here, due to the Python 3.9 deprecation warning.
+            assert_empty!(context.pack_stderr);
             assert_contains!(
                 context.pack_stdout,
                 indoc! {"
@@ -99,11 +99,7 @@ fn django_invalid_settings_module() {
                 context.pack_stdout,
                 indoc! {"
                     [Generating Django static files]
-                "}
-            );
-            assert_contains!(
-                context.pack_stderr,
-                indoc! {"
+
                     [Error: Unable to inspect Django configuration]
                     The 'python manage.py help collectstatic' Django management command
                     (used to check whether Django's static files feature is enabled)
@@ -116,14 +112,16 @@ fn django_invalid_settings_module() {
             );
             // Full traceback omitted since it will change across Django/Python versions causing test churn.
             assert_contains!(
-                context.pack_stderr,
+                context.pack_stdout,
                 indoc! {"
                     ModuleNotFoundError: No module named 'nonexistent-module'
                     
                     
                     This indicates there is a problem with your application code or Django
                     configuration. Try running the 'manage.py' script locally to see if the
                     same error occurs.
+
+                    ERROR: failed to build: exit status 1
                 "}
             );
         },
@@ -142,11 +140,15 @@ fn django_staticfiles_misconfigured() {
                 indoc! {"
                     [Generating Django static files]
                     Running 'manage.py collectstatic'
+                    Traceback (most recent call last):
                 "}
             );
+            // Full traceback omitted since it will change across Django/Python versions causing test churn.
             assert_contains!(
-                context.pack_stderr,
+                context.pack_stdout,
                 indoc! {"
+                    django.core.exceptions.ImproperlyConfigured: You're using the staticfiles app without having set the required STATIC_URL setting.
+
                     [Error: Unable to generate Django static files]
                     The 'python manage.py collectstatic --noinput' Django management
                     command to generate static files failed (exit status: 1).
@@ -162,6 +164,8 @@ fn django_staticfiles_misconfigured() {
                     Or, if you do not need to use static files in your app, disable the
                     Django static files feature by removing 'django.contrib.staticfiles'
                     from 'INSTALLED_APPS' in your app's Django configuration.
+
+                    ERROR: failed to build: exit status 1
                 "}
             );
         },
diff --git a/tests/package_manager_test.rs b/tests/package_manager_test.rs
@@ -10,7 +10,7 @@ fn no_package_manager_detected() {
             .expected_pack_result(PackResult::Failure),
         |context| {
             assert_contains!(
-                context.pack_stderr,
+                context.pack_stdout,
                 indoc! {"
                     [Error: Couldn't find any supported Python package manager files]
                     Your app must have either a 'requirements.txt', 'poetry.lock'
@@ -36,6 +36,8 @@ fn no_package_manager_detected() {
                     For help with using Python on Heroku, see:
                     https://devcenter.heroku.com/articles/getting-started-with-python-fir
                     https://devcenter.heroku.com/articles/python-support
+
+                    ERROR: failed to build: exit status 1
                 "}
             );
         },
@@ -50,7 +52,7 @@ fn multiple_package_managers_detected() {
             .expected_pack_result(PackResult::Failure),
         |context| {
             assert_contains!(
-                context.pack_stderr,
+                context.pack_stdout,
                 indoc! {"
                     [Error: Multiple Python package manager files were found]
                     Exactly one package manager file must be present in your app's
@@ -67,6 +69,8 @@ fn multiple_package_managers_detected() {
                     trying uv, since it supports lockfiles, is extremely fast, and
                     is actively maintained by a full-time team:
                     https://docs.astral.sh/uv/
+
+                    ERROR: failed to build: exit status 1
                 "}
             );
         },
diff --git a/tests/pip_test.rs b/tests/pip_test.rs
@@ -216,7 +216,7 @@ fn pip_editable_git_compiled() {
     config.env("WHEEL_PACKAGE_URL", "https://github.com/pypa/wheel.git");
 
     TestRunner::default().build(config, |context| {
-        // We can't `assert_empty!(context.pack_stderr)` here, since the git clone steps print to stderr.
+        assert_empty!(context.pack_stderr);
         assert_contains!(
             context.pack_stdout,
             "Cloning https://github.com/pypa/wheel.git (to revision 0.44.0) to /layers/heroku_python/venv/src/extension-dist"
@@ -232,9 +232,12 @@ fn pip_oldest_python() {
     let config = default_build_config("tests/fixtures/pip_oldest_python");
 
     TestRunner::default().build(config, |context| {
-        assert_eq!(
-            context.pack_stderr,
+        assert_empty!(context.pack_stderr);
+        assert_contains!(
+            context.pack_stdout,
             indoc! {"
+                [Determining Python version]
+                Using Python version 3.9.0 specified in .python-version
                 
                 [Warning: Support for Python 3.9 is deprecated]
                 Python 3.9 will reach its upstream end-of-life in October 2025,
@@ -250,14 +253,7 @@ fn pip_oldest_python() {
                 For more information, see:
                 https://devcenter.heroku.com/articles/python-support#supported-python-versions
                 
-            "}
-        );
-        assert_contains!(
-            context.pack_stdout,
-            indoc! {"
-                [Determining Python version]
-                Using Python version 3.9.0 specified in .python-version
-                
+
                 [Installing Python]
                 Installing Python 3.9.0
             "}
@@ -272,19 +268,12 @@ fn pip_install_error() {
     config.expected_pack_result(PackResult::Failure);
 
     TestRunner::default().build(config, |context| {
-        // Ideally we could test a combined stdout/stderr, however libcnb-test doesn't support this:
-        // https://github.com/heroku/libcnb.rs/issues/536
         assert_contains!(
             context.pack_stdout,
             indoc! {"
                 [Installing dependencies using pip]
                 Creating virtual environment
                 Running 'pip install -r requirements.txt'
-            "}
-        );
-        assert_contains!(
-            context.pack_stderr,
-            indoc! {"
                 ERROR: Invalid requirement: 'an-invalid-requirement!': Expected end or semicolon (after name and no valid version specifier)
                     an-invalid-requirement!
                                           ^ (from line 1 of requirements.txt)
@@ -294,6 +283,8 @@ fn pip_install_error() {
                 dependencies failed (exit status: 1).
                 
                 See the log output above for more information.
+
+                ERROR: failed to build: exit status 1
             "}
         );
     });
diff --git a/tests/poetry_test.rs b/tests/poetry_test.rs
@@ -234,12 +234,27 @@ fn poetry_oldest_python() {
     let config = default_build_config("tests/fixtures/poetry_oldest_python");
 
     TestRunner::default().build(config, |context| {
-        // We can't `assert_empty!(context.pack_stderr)` here, due to the Python 3.9 deprecation warning.
+        assert_empty!(context.pack_stderr);
         assert_contains!(
             context.pack_stdout,
             &formatdoc! {"
                 [Determining Python version]
                 Using Python version 3.9.0 specified in .python-version
+
+                [Warning: Support for Python 3.9 is deprecated]
+                Python 3.9 will reach its upstream end-of-life in October 2025,
+                at which point it will no longer receive security updates:
+                https://devguide.python.org/versions/#supported-versions
+                
+                As such, support for Python 3.9 will be removed from this
+                buildpack on 7th January 2026.
+                
+                Upgrade to a newer Python version as soon as possible, by
+                changing the version in your .python-version file.
+                
+                For more information, see:
+                https://devcenter.heroku.com/articles/python-support#supported-python-versions
+                
                 
                 [Installing Python]
                 Installing Python 3.9.0
@@ -269,19 +284,13 @@ fn poetry_mismatched_python_version() {
     config.expected_pack_result(PackResult::Failure);
 
     TestRunner::default().build(config, |context| {
-        // Ideally we could test a combined stdout/stderr, however libcnb-test doesn't support this:
-        // https://github.com/heroku/libcnb.rs/issues/536
         assert_contains!(
             context.pack_stdout,
-            indoc! {"
+            &formatdoc! {r#"
                 [Installing dependencies using Poetry]
                 Creating virtual environment
                 Running 'poetry sync --only main'
-            "}
-        );
-        assert_contains!(
-            context.pack_stderr,
-            &formatdoc! {r#"
+
                 Current Python version ({DEFAULT_PYTHON_FULL_VERSION}) is not allowed by the project (3.12.*).
                 Please change python executable via the "env use" command.
                 
@@ -290,6 +299,8 @@ fn poetry_mismatched_python_version() {
                 dependencies failed (exit status: 1).
                 
                 See the log output above for more information.
+
+                ERROR: failed to build: exit status 1
             "#}
         );
     });
@@ -302,27 +313,23 @@ fn poetry_lockfile_out_of_sync() {
     config.expected_pack_result(PackResult::Failure);
 
     TestRunner::default().build(config, |context| {
-        // Ideally we could test a combined stdout/stderr, however libcnb-test doesn't support this:
-        // https://github.com/heroku/libcnb.rs/issues/536
         assert_contains!(
             context.pack_stdout,
             indoc! {"
                 [Installing dependencies using Poetry]
                 Creating virtual environment
                 Running 'poetry sync --only main'
                 Installing dependencies from lock file
-            "}
-        );
-        assert_contains!(
-            context.pack_stderr,
-            indoc! {"
+
                 pyproject.toml changed significantly since poetry.lock was last generated. Run `poetry lock` to fix the lock file.
                 
                 [Error: Unable to install dependencies using Poetry]
                 The 'poetry sync --only main' command to install the app's
                 dependencies failed (exit status: 1).
                 
                 See the log output above for more information.
+
+                ERROR: failed to build: exit status 1
             "}
         );
     });
diff --git a/tests/python_version_test.rs b/tests/python_version_test.rs
diff --git a/tests/uv_test.rs b/tests/uv_test.rs
