diff --git a/syncstorage-spanner/src/error.rs b/syncstorage-spanner/src/error.rs
index 64c45adf..4f3ef73c 100644
--- a/syncstorage-spanner/src/error.rs
+++ b/syncstorage-spanner/src/error.rs
@@ -11,7 +11,7 @@ use thiserror::Error;
 /// from the database backend.
 #[derive(Debug)]
 pub struct DbError {
-    kind: DbErrorKind,
+    pub(crate) kind: DbErrorKind,
     pub status: StatusCode,
     pub backtrace: Box<Backtrace>,
 }
@@ -55,7 +55,7 @@ impl DbError {
 }
 
 #[derive(Debug, Error)]
-enum DbErrorKind {
+pub(crate) enum DbErrorKind {
     #[error("{}", _0)]
     Common(SyncstorageDbError),
 
diff --git a/syncstorage-spanner/src/lib.rs b/syncstorage-spanner/src/lib.rs
index 02aaa25c..e00a6d80 100644
--- a/syncstorage-spanner/src/lib.rs
+++ b/syncstorage-spanner/src/lib.rs
@@ -12,6 +12,7 @@ mod manager;
 mod metadata;
 mod models;
 mod pool;
+mod stream;
 mod support;
 
 pub use error::DbError;
diff --git a/syncstorage-spanner/src/stream.rs b/syncstorage-spanner/src/stream.rs
new file mode 100644
index 00000000..694541c7
--- /dev/null
+++ b/syncstorage-spanner/src/stream.rs
@@ -0,0 +1,261 @@
+use std::{collections::VecDeque, mem};
+
+use futures::{stream::StreamFuture, Stream, StreamExt};
+use google_cloud_rust_raw::spanner::v1::{
+    result_set::{PartialResultSet, ResultSetMetadata, ResultSetStats},
+    type_pb::{StructType_Field, Type, TypeCode},
+};
+use grpcio::ClientSStreamReceiver;
+use protobuf::well_known_types::Value;
+
+use crate::{error::DbError, support::IntoSpannerValue, DbResult};
+
+pub struct StreamedResultSetAsync<T = ClientSStreamReceiver<PartialResultSet>> {
+    /// Stream from execute_streaming_sql
+    stream: Option<StreamFuture<T>>,
+
+    metadata: Option<ResultSetMetadata>,
+    stats: Option<ResultSetStats>,
+
+    /// Fully-processed rows
+    rows: VecDeque<Vec<Value>>,
+    /// Accumulated values for incomplete row
+    current_row: Vec<Value>,
+    /// Incomplete value
+    pending_chunk: Option<Value>,
+}
+
+impl<T> StreamedResultSetAsync<T>
+where
+    T: Stream<Item = grpcio::Result<PartialResultSet>> + Unpin,
+{
+    pub fn new(stream: T) -> Self {
+        Self {
+            stream: Some(stream.into_future()),
+            metadata: None,
+            stats: None,
+            rows: Default::default(),
+            current_row: vec![],
+            pending_chunk: None,
+        }
+    }
+
+    #[allow(dead_code)]
+    pub fn metadata(&self) -> Option<&ResultSetMetadata> {
+        self.metadata.as_ref()
+    }
+
+    #[allow(dead_code)]
+    pub fn stats(&self) -> Option<&ResultSetStats> {
+        self.stats.as_ref()
+    }
+
+    pub fn fields(&self) -> &[StructType_Field] {
+        match self.metadata {
+            Some(ref metadata) => metadata.get_row_type().get_fields(),
+            None => &[],
+        }
+    }
+
+    pub async fn one(&mut self) -> DbResult<Vec<Value>> {
+        if let Some(result) = self.one_or_none().await? {
+            Ok(result)
+        } else {
+            Err(DbError::internal(
+                "No rows matched the given query.".to_owned(),
+            ))
+        }
+    }
+
+    pub async fn one_or_none(&mut self) -> DbResult<Option<Vec<Value>>> {
+        let result = self.next_async().await;
+        if result.is_none() {
+            Ok(None)
+        } else if self.next_async().await.is_some() {
+            Err(DbError::internal(
+                "Expected one result; got more.".to_owned(),
+            ))
+        } else {
+            result.transpose()
+        }
+    }
+
+    /// Pull and process the next values from the Stream
+    ///
+    /// Returns false when the stream is finished
+    async fn consume_next(&mut self) -> DbResult<bool> {
+        let (result, stream) = self
+            .stream
+            .take()
+            .expect("Could not get next stream element")
+            .await;
+
+        self.stream = Some(stream.into_future());
+        let mut partial_rs = if let Some(result) = result {
+            result?
+        } else {
+            // Stream finished
+            return Ok(false);
+        };
+
+        if self.metadata.is_none() && partial_rs.has_metadata() {
+            // first response
+            self.metadata = Some(partial_rs.take_metadata());
+        }
+        if partial_rs.has_stats() {
+            // last response
+            self.stats = Some(partial_rs.take_stats());
+        }
+
+        let mut values = partial_rs.take_values().into_vec();
+        if values.is_empty() {
+            // sanity check
+            return Ok(true);
+        }
+
+        if let Some(pending_chunk) = self.pending_chunk.take() {
+            let fields = self.fields();
+            let current_row_i = self.current_row.len();
+            if fields.len() <= current_row_i {
+                return Err(DbError::integrity(
+                    "Invalid PartialResultSet fields".to_owned(),
+                ));
+            }
+            let field = &fields[current_row_i];
+            values[0] = merge_by_type(pending_chunk, &values[0], field.get_field_type())?;
+        }
+        if partial_rs.get_chunked_value() {
+            self.pending_chunk = values.pop();
+        }
+
+        self.consume_values(values);
+        Ok(true)
+    }
+
+    fn consume_values(&mut self, values: Vec<Value>) {
+        let width = self.fields().len();
+        for value in values {
+            self.current_row.push(value);
+            if self.current_row.len() == width {
+                let current_row = mem::take(&mut self.current_row);
+                self.rows.push_back(current_row);
+            }
+        }
+    }
+
+    // We could implement Stream::poll_next instead of this, but
+    // this is easier for now and we can refactor into the trait later
+    pub async fn next_async(&mut self) -> Option<DbResult<Vec<Value>>> {
+        while self.rows.is_empty() {
+            match self.consume_next().await {
+                Ok(true) => (),
+                Ok(false) => return None,
+                // Note: Iteration may continue after an error. We may want to
+                // stop afterwards instead for safety sake (it's not really
+                // recoverable)
+                Err(e) => return Some(Err(e)),
+            }
+        }
+        Ok(self.rows.pop_front()).transpose()
+    }
+}
+
+fn merge_by_type(lhs: Value, rhs: &Value, field_type: &Type) -> DbResult<Value> {
+    // We only support merging basic string types as that's all we currently use.
+    // The python client also supports: float64, array, struct. The go client
+    // only additionally supports array (claiming structs are only returned as
+    // arrays anyway)
+    match field_type.get_code() {
+        TypeCode::BYTES
+        | TypeCode::DATE
+        | TypeCode::INT64
+        | TypeCode::STRING
+        | TypeCode::TIMESTAMP => merge_string(lhs, rhs),
+        _ => unsupported_merge(field_type),
+    }
+}
+
+fn unsupported_merge(field_type: &Type) -> DbResult<Value> {
+    Err(DbError::internal(format!(
+        "merge not supported, type: {:?}",
+        field_type
+    )))
+}
+
+fn merge_string(mut lhs: Value, rhs: &Value) -> DbResult<Value> {
+    if !lhs.has_string_value() || !rhs.has_string_value() {
+        return Err(DbError::internal(
+            "merge_string has no string value".to_owned(),
+        ));
+    }
+    let mut merged = lhs.take_string_value();
+    merged.push_str(rhs.get_string_value());
+    Ok(merged.into_spanner_value())
+}
+
+#[cfg(test)]
+mod tests {
+    use futures::stream;
+    use google_cloud_rust_raw::spanner::v1::{
+        result_set::{PartialResultSet, ResultSetMetadata},
+        type_pb::{StructType, StructType_Field, Type, TypeCode},
+    };
+    use grpcio::Error::GoogleAuthenticationFailed;
+    use protobuf::well_known_types::Value;
+
+    use super::StreamedResultSetAsync;
+    use crate::error::DbErrorKind;
+
+    fn simple_part() -> PartialResultSet {
+        let mut field_type = Type::default();
+        field_type.set_code(TypeCode::INT64);
+
+        let mut field = StructType_Field::default();
+        field.set_name("foo".to_owned());
+        field.set_field_type(field_type);
+
+        let mut row_type = StructType::default();
+        row_type.set_fields(vec![field].into());
+
+        let mut metadata = ResultSetMetadata::default();
+        metadata.set_row_type(row_type);
+
+        let mut part = PartialResultSet::default();
+        part.set_metadata(metadata);
+
+        let mut value = Value::default();
+        value.set_string_value("22".to_owned());
+        part.set_values(vec![value].into());
+
+        part
+    }
+
+    #[actix_web::test]
+    async fn consume_next_err() {
+        let mut s = StreamedResultSetAsync::new(stream::iter([
+            Ok(simple_part()),
+            Err(GoogleAuthenticationFailed),
+        ]));
+        assert!(s.consume_next().await.unwrap());
+        let err = s.consume_next().await.unwrap_err();
+        assert!(matches!(
+            err.kind,
+            DbErrorKind::Grpc(GoogleAuthenticationFailed)
+        ));
+    }
+
+    #[actix_web::test]
+    async fn one_or_none_err_propagate() {
+        let mut s = StreamedResultSetAsync::new(stream::iter([
+            Ok(simple_part()),
+            Err(GoogleAuthenticationFailed),
+        ]));
+        let _err = s.one_or_none().await.unwrap_err();
+        // XXX: https://github.com/mozilla-services/syncstorage-rs/issues/1384
+        //dbg!(&err);
+        //assert!(matches!(
+        //    err.kind,
+        //    DbErrorKind::Grpc(GoogleAuthenticationFailed)
+        //));
+    }
+}
diff --git a/syncstorage-spanner/src/support.rs b/syncstorage-spanner/src/support.rs
index 59ea7023..533067e2 100644
--- a/syncstorage-spanner/src/support.rs
+++ b/syncstorage-spanner/src/support.rs
@@ -1,15 +1,10 @@
-use std::{
-    collections::{HashMap, VecDeque},
-    mem,
-};
+use std::collections::HashMap;
 
-use futures::stream::{StreamExt, StreamFuture};
 use google_cloud_rust_raw::spanner::v1::{
-    result_set::{PartialResultSet, ResultSetMetadata, ResultSetStats},
     spanner::ExecuteSqlRequest,
     type_pb::{StructType_Field, Type, TypeCode},
 };
-use grpcio::ClientSStreamReceiver;
+
 use protobuf::{
     well_known_types::{ListValue, NullValue, Struct, Value},
     RepeatedField,
@@ -18,6 +13,7 @@ use syncstorage_db_common::{
     params, results, util::to_rfc3339, util::SyncTimestamp, UserIdentifier, DEFAULT_BSO_TTL,
 };
 
+pub use crate::stream::StreamedResultSetAsync;
 use crate::{error::DbError, pool::Conn, DbResult};
 
 pub trait IntoSpannerValue {
@@ -181,186 +177,6 @@ impl ExecuteSqlRequestBuilder {
     }
 }
 
-pub struct StreamedResultSetAsync {
-    /// Stream from execute_streaming_sql
-    stream: Option<StreamFuture<ClientSStreamReceiver<PartialResultSet>>>,
-
-    metadata: Option<ResultSetMetadata>,
-    stats: Option<ResultSetStats>,
-
-    /// Fully-processed rows
-    rows: VecDeque<Vec<Value>>,
-    /// Accumulated values for incomplete row
-    current_row: Vec<Value>,
-    /// Incomplete value
-    pending_chunk: Option<Value>,
-}
-
-impl StreamedResultSetAsync {
-    pub fn new(stream: ClientSStreamReceiver<PartialResultSet>) -> Self {
-        Self {
-            stream: Some(stream.into_future()),
-            metadata: None,
-            stats: None,
-            rows: Default::default(),
-            current_row: vec![],
-            pending_chunk: None,
-        }
-    }
-
-    #[allow(dead_code)]
-    pub fn metadata(&self) -> Option<&ResultSetMetadata> {
-        self.metadata.as_ref()
-    }
-
-    #[allow(dead_code)]
-    pub fn stats(&self) -> Option<&ResultSetStats> {
-        self.stats.as_ref()
-    }
-
-    pub fn fields(&self) -> &[StructType_Field] {
-        match self.metadata {
-            Some(ref metadata) => metadata.get_row_type().get_fields(),
-            None => &[],
-        }
-    }
-
-    pub async fn one(&mut self) -> DbResult<Vec<Value>> {
-        if let Some(result) = self.one_or_none().await? {
-            Ok(result)
-        } else {
-            Err(DbError::internal(
-                "No rows matched the given query.".to_owned(),
-            ))
-        }
-    }
-
-    pub async fn one_or_none(&mut self) -> DbResult<Option<Vec<Value>>> {
-        let result = self.next_async().await;
-        if result.is_none() {
-            Ok(None)
-        } else if self.next_async().await.is_some() {
-            Err(DbError::internal(
-                "Expected one result; got more.".to_owned(),
-            ))
-        } else {
-            result.transpose()
-        }
-    }
-
-    /// Pull and process the next values from the Stream
-    ///
-    /// Returns false when the stream is finished
-    async fn consume_next(&mut self) -> DbResult<bool> {
-        let (result, stream) = self
-            .stream
-            .take()
-            .expect("Could not get next stream element")
-            .await;
-
-        self.stream = Some(stream.into_future());
-        let mut partial_rs = if let Some(result) = result {
-            result?
-        } else {
-            // Stream finished
-            return Ok(false);
-        };
-
-        if self.metadata.is_none() && partial_rs.has_metadata() {
-            // first response
-            self.metadata = Some(partial_rs.take_metadata());
-        }
-        if partial_rs.has_stats() {
-            // last response
-            self.stats = Some(partial_rs.take_stats());
-        }
-
-        let mut values = partial_rs.take_values().into_vec();
-        if values.is_empty() {
-            // sanity check
-            return Ok(true);
-        }
-
-        if let Some(pending_chunk) = self.pending_chunk.take() {
-            let fields = self.fields();
-            let current_row_i = self.current_row.len();
-            if fields.len() <= current_row_i {
-                return Err(DbError::integrity(
-                    "Invalid PartialResultSet fields".to_owned(),
-                ));
-            }
-            let field = &fields[current_row_i];
-            values[0] = merge_by_type(pending_chunk, &values[0], field.get_field_type())?;
-        }
-        if partial_rs.get_chunked_value() {
-            self.pending_chunk = values.pop();
-        }
-
-        self.consume_values(values);
-        Ok(true)
-    }
-
-    fn consume_values(&mut self, values: Vec<Value>) {
-        let width = self.fields().len();
-        for value in values {
-            self.current_row.push(value);
-            if self.current_row.len() == width {
-                let current_row = mem::take(&mut self.current_row);
-                self.rows.push_back(current_row);
-            }
-        }
-    }
-
-    // We could implement Stream::poll_next instead of this, but
-    // this is easier for now and we can refactor into the trait later
-    pub async fn next_async(&mut self) -> Option<DbResult<Vec<Value>>> {
-        while self.rows.is_empty() {
-            match self.consume_next().await {
-                Ok(true) => (),
-                Ok(false) => return None,
-                // Note: Iteration may continue after an error. We may want to
-                // stop afterwards instead for safety sake (it's not really
-                // recoverable)
-                Err(e) => return Some(Err(e)),
-            }
-        }
-        Ok(self.rows.pop_front()).transpose()
-    }
-}
-
-fn merge_by_type(lhs: Value, rhs: &Value, field_type: &Type) -> DbResult<Value> {
-    // We only support merging basic string types as that's all we currently use.
-    // The python client also supports: float64, array, struct. The go client
-    // only additionally supports array (claiming structs are only returned as
-    // arrays anyway)
-    match field_type.get_code() {
-        TypeCode::BYTES
-        | TypeCode::DATE
-        | TypeCode::INT64
-        | TypeCode::STRING
-        | TypeCode::TIMESTAMP => merge_string(lhs, rhs),
-        _ => unsupported_merge(field_type),
-    }
-}
-
-fn unsupported_merge(field_type: &Type) -> DbResult<Value> {
-    Err(DbError::internal(format!(
-        "merge not supported, type: {:?}",
-        field_type
-    )))
-}
-
-fn merge_string(mut lhs: Value, rhs: &Value) -> DbResult<Value> {
-    if !lhs.has_string_value() || !rhs.has_string_value() {
-        return Err(DbError::internal(
-            "merge_string has no string value".to_owned(),
-        ));
-    }
-    let mut merged = lhs.take_string_value();
-    merged.push_str(rhs.get_string_value());
-    Ok(merged.into_spanner_value())
-}
-
 pub fn bso_from_row(mut row: Vec<Value>) -> DbResult<results::GetBso> {
     let modified_string = &row[3].get_string_value();
     let modified = SyncTimestamp::from_rfc3339(modified_string)