From c1a39e4067362d6e699573c4be4a92cef044766f Mon Sep 17 00:00:00 2001
From: Mykola Rybak <mykola.rybak@thredup.com>
Date: Tue, 30 Jan 2024 21:44:37 +0200
Subject: [PATCH] enhancement(unit tests): Enable population of event metadata
 by a VRL unit test source (#19729)

* Enable population of event metadata by a VRL source

At the moment, there seems to be no way to produce an event with
non-trivial metadata for a unit test, which makes it hard to test
configurations that have log_namespace = true.

Reference: https://github.com/vectordotdev/vector/issues/19639.

* Add changelog snippet

* Fix changelog snippet name

* Fix unit test transform name clash
---
 ...9639_unit_test_vrl_metadata.enhancement.md |  3 ++
 src/config/unit_test/mod.rs                   |  9 ++++--
 tests/behavior/transforms/vrl_test_input.toml | 29 +++++++++++++++++++
 3 files changed, 39 insertions(+), 2 deletions(-)
 create mode 100644 changelog.d/19639_unit_test_vrl_metadata.enhancement.md

diff --git a/changelog.d/19639_unit_test_vrl_metadata.enhancement.md b/changelog.d/19639_unit_test_vrl_metadata.enhancement.md
new file mode 100644
index 0000000000000..dc03333a5f3be
--- /dev/null
+++ b/changelog.d/19639_unit_test_vrl_metadata.enhancement.md
@@ -0,0 +1,3 @@
+Unit tests can now populate event metadata with the `% = ...` syntax.
+
+authors: GreyTeardrop
diff --git a/src/config/unit_test/mod.rs b/src/config/unit_test/mod.rs
index 78148b356825e..f5402af37f9cb 100644
--- a/src/config/unit_test/mod.rs
+++ b/src/config/unit_test/mod.rs
@@ -32,7 +32,7 @@ use crate::{
         self, loading, ComponentKey, Config, ConfigBuilder, ConfigPath, SinkOuter, SourceOuter,
         TestDefinition, TestInput, TestInputValue, TestOutput,
     },
-    event::{Event, LogEvent, Value},
+    event::{Event, EventMetadata, LogEvent, Value},
     signal,
     topology::{builder::TopologyPieces, RunningTopology},
 };
@@ -581,7 +581,12 @@ fn build_input_event(input: &TestInput) -> Result<Event, String> {
                 result
                     .program
                     .resolve(&mut ctx)
-                    .map(|v| Event::Log(LogEvent::from(v.clone())))
+                    .map(|_| {
+                        Event::Log(LogEvent::from_parts(
+                            target.value.clone(),
+                            EventMetadata::default_with_value(target.metadata.clone()),
+                        ))
+                    })
                     .map_err(|e| e.to_string())
             } else {
                 Err("input type 'vrl' requires the field 'source'".to_string())
diff --git a/tests/behavior/transforms/vrl_test_input.toml b/tests/behavior/transforms/vrl_test_input.toml
index fab976d8029ed..ef148a29dfeb9 100644
--- a/tests/behavior/transforms/vrl_test_input.toml
+++ b/tests/behavior/transforms/vrl_test_input.toml
@@ -17,3 +17,32 @@
     [[tests.outputs.conditions]]
       type = "vrl"
       source = """.a.b == "c" && is_timestamp(.d)"""
+
+##------------------------------------------------------------------------------
+
+[transforms.remap_test_metadata]
+  inputs = []
+  type = "remap"
+  source = '''
+    .event = .
+    .metadata = %
+  '''
+
+[[tests]]
+  name = "remap_test_metadata"
+  [[tests.inputs]]
+    insert_at = "remap_test_metadata"
+    type = "vrl"
+    source = '''
+      . = "Event"
+      % = "Metadata"
+    '''
+
+  [[tests.outputs]]
+    extract_from = "remap_test_metadata"
+    [[tests.outputs.conditions]]
+      type = "vrl"
+      source = '''
+        assert_eq!(.event, "Event")
+        assert_eq!(.metadata, "Metadata")
+      '''