1 files changed, 99 insertions, 0 deletions
diff --git a/third_party/rust/tracing/tests/support/event.rs b/third_party/rust/tracing/tests/support/event.rs
new file mode 100644
index 0000000000..7033d8a134
--- /dev/null
+++ b/third_party/rust/tracing/tests/support/event.rs
@@ -0,0 +1,99 @@
+#![allow(missing_docs)]
+use super::{field, metadata, Parent};
+
+use std::fmt;
+
+/// A mock event.
+///
+/// This is intended for use with the mock subscriber API in the
+/// `subscriber` module.
+#[derive(Debug, Default, Eq, PartialEq)]
+pub struct MockEvent {
+    pub fields: Option<field::Expect>,
+    pub(in crate::support) parent: Option<Parent>,
+    metadata: metadata::Expect,
+}
+
+pub fn mock() -> MockEvent {
+    MockEvent {
+        ..Default::default()
+    }
+}
+
+impl MockEvent {
+    pub fn named<I>(self, name: I) -> Self
+    where
+        I: Into<String>,
+    {
+        Self {
+            metadata: metadata::Expect {
+                name: Some(name.into()),
+                ..self.metadata
+            },
+            ..self
+        }
+    }
+
+    pub fn with_fields<I>(self, fields: I) -> Self
+    where
+        I: Into<field::Expect>,
+    {
+        Self {
+            fields: Some(fields.into()),
+            ..self
+        }
+    }
+
+    pub fn at_level(self, level: tracing::Level) -> Self {
+        Self {
+            metadata: metadata::Expect {
+                level: Some(level),
+                ..self.metadata
+            },
+            ..self
+        }
+    }
+
+    pub fn with_target<I>(self, target: I) -> Self
+    where
+        I: Into<String>,
+    {
+        Self {
+            metadata: metadata::Expect {
+                target: Some(target.into()),
+                ..self.metadata
+            },
+            ..self
+        }
+    }
+
+    pub fn with_explicit_parent(self, parent: Option<&str>) -> MockEvent {
+        let parent = match parent {
+            Some(name) => Parent::Explicit(name.into()),
+            None => Parent::ExplicitRoot,
+        };
+        Self {
+            parent: Some(parent),
+            ..self
+        }
+    }
+
+    pub(in crate::support) fn check(&mut self, event: &tracing::Event<'_>) {
+        let meta = event.metadata();
+        let name = meta.name();
+        self.metadata
+            .check(meta, format_args!("event \"{}\"", name));
+        assert!(meta.is_event(), "expected {}, but got {:?}", self, event);
+        if let Some(ref mut expected_fields) = self.fields {
+            let mut checker = expected_fields.checker(name.to_string());
+            event.record(&mut checker);
+            checker.finish();
+        }
+    }
+}
+
+impl fmt::Display for MockEvent {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "an event{}", self.metadata)
+    }
+}