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	In `pgStatWalReceiverQueryTemplate`, the order of the columns (when `hasFlushedLSN == true`) is:
- ...
- `receive_start_lsn`
- `flushed_lsn`
- `receive_start_tli`
- ...
However, columns were scanned in this order:
- ...
- `receive_start_lsn` -> `receiveStartLsn`
- `receive_start_tli` -> `flushedLsn` (!)
- `flushed_lsn` -> `receiveStartTli` (!)
- ...
This incorrect hydration of variables also manifests as swapped values for the
`pg_stat_wal_receiver_flushed_lsn` and `pg_stat_wal_receiver_receive_start_tli` metrics.
This seems to be a bug that has existed since the initial implementation:
- 2d7e152751
- https://github.com/prometheus-community/postgres_exporter/pull/844
In this patch, I'm:
- fixing the `.Scan()`, so that it hydrates variables in the correct order
- adjusting the order in which metrics are pushed out to the channel,
  to follow the order we consume them in
  (.., `receive_start_lsn`, `flushed_lsn`, `receive_start_tli`, ..)
- adjusting the walreceiver tests, to follow the new order (which matches .`Scan()`)
- fixing a small identation issue in `pgStatWalReceiverQueryTemplate`
Signed-off-by: Slavi Pantaleev <slavi@devture.com>
		
	
		
			
				
	
	
		
			187 lines
		
	
	
		
			6.4 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			187 lines
		
	
	
		
			6.4 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
// Copyright 2023 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package collector
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import (
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	"context"
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	"fmt"
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	"testing"
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	"github.com/DATA-DOG/go-sqlmock"
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	"github.com/prometheus/client_golang/prometheus"
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	dto "github.com/prometheus/client_model/go"
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	"github.com/smartystreets/goconvey/convey"
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)
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var queryWithFlushedLSN = fmt.Sprintf(pgStatWalReceiverQueryTemplate, "(flushed_lsn - '0/0') % (2^52)::bigint as flushed_lsn,\n")
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var queryWithNoFlushedLSN = fmt.Sprintf(pgStatWalReceiverQueryTemplate, "")
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func TestPGStatWalReceiverCollectorWithFlushedLSN(t *testing.T) {
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	db, mock, err := sqlmock.New()
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	if err != nil {
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		t.Fatalf("Error opening a stub db connection: %s", err)
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	}
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	defer db.Close()
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	inst := &instance{db: db}
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	infoSchemaColumns := []string{
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		"column_name",
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	}
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	infoSchemaRows := sqlmock.NewRows(infoSchemaColumns).
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		AddRow(
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			"flushed_lsn",
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		)
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	mock.ExpectQuery(sanitizeQuery(pgStatWalColumnQuery)).WillReturnRows(infoSchemaRows)
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	columns := []string{
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		"upstream_host",
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		"slot_name",
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		"status",
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		"receive_start_lsn",
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		"flushed_lsn",
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		"receive_start_tli",
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		"received_tli",
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		"last_msg_send_time",
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		"last_msg_receipt_time",
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		"latest_end_lsn",
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		"latest_end_time",
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		"upstream_node",
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	}
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	rows := sqlmock.NewRows(columns).
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		AddRow(
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			"foo",
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			"bar",
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			"stopping",
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			int64(1200668684563608),
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			int64(1200668684563609),
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			1687321285,
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			1687321280,
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			1687321275,
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			1687321276,
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			int64(1200668684563610),
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			1687321277,
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			5,
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		)
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	mock.ExpectQuery(sanitizeQuery(queryWithFlushedLSN)).WillReturnRows(rows)
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	ch := make(chan prometheus.Metric)
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	go func() {
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		defer close(ch)
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		c := PGStatWalReceiverCollector{}
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		if err := c.Update(context.Background(), inst, ch); err != nil {
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			t.Errorf("Error calling PgStatWalReceiverCollector.Update: %s", err)
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		}
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	}()
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	expected := []MetricResult{
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "stopping"}, value: 1200668684563608, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "stopping"}, value: 1200668684563609, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "stopping"}, value: 1687321285, metricType: dto.MetricType_GAUGE},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "stopping"}, value: 1687321280, metricType: dto.MetricType_GAUGE},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "stopping"}, value: 1687321275, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "stopping"}, value: 1687321276, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "stopping"}, value: 1200668684563610, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "stopping"}, value: 1687321277, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "stopping"}, value: 5, metricType: dto.MetricType_GAUGE},
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	}
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	convey.Convey("Metrics comparison", t, func() {
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		for _, expect := range expected {
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			m := readMetric(<-ch)
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			convey.So(expect, convey.ShouldResemble, m)
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		}
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	})
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	if err := mock.ExpectationsWereMet(); err != nil {
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		t.Errorf("there were unfulfilled exceptions: %s", err)
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	}
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}
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func TestPGStatWalReceiverCollectorWithNoFlushedLSN(t *testing.T) {
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	db, mock, err := sqlmock.New()
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	if err != nil {
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		t.Fatalf("Error opening a stub db connection: %s", err)
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	}
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	defer db.Close()
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	inst := &instance{db: db}
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	infoSchemaColumns := []string{
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		"column_name",
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	}
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	infoSchemaRows := sqlmock.NewRows(infoSchemaColumns)
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	mock.ExpectQuery(sanitizeQuery(pgStatWalColumnQuery)).WillReturnRows(infoSchemaRows)
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	columns := []string{
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		"upstream_host",
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		"slot_name",
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		"status",
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		"receive_start_lsn",
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		"receive_start_tli",
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		"received_tli",
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		"last_msg_send_time",
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		"last_msg_receipt_time",
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		"latest_end_lsn",
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		"latest_end_time",
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		"upstream_node",
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	}
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	rows := sqlmock.NewRows(columns).
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		AddRow(
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			"foo",
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			"bar",
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			"starting",
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			int64(1200668684563608),
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			1687321285,
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			1687321280,
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			1687321275,
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			1687321276,
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			int64(1200668684563610),
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			1687321277,
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			5,
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		)
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	mock.ExpectQuery(sanitizeQuery(queryWithNoFlushedLSN)).WillReturnRows(rows)
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	ch := make(chan prometheus.Metric)
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	go func() {
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		defer close(ch)
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		c := PGStatWalReceiverCollector{}
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		if err := c.Update(context.Background(), inst, ch); err != nil {
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			t.Errorf("Error calling PgStatWalReceiverCollector.Update: %s", err)
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		}
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	}()
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	expected := []MetricResult{
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "starting"}, value: 1200668684563608, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "starting"}, value: 1687321285, metricType: dto.MetricType_GAUGE},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "starting"}, value: 1687321280, metricType: dto.MetricType_GAUGE},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "starting"}, value: 1687321275, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "starting"}, value: 1687321276, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "starting"}, value: 1200668684563610, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "starting"}, value: 1687321277, metricType: dto.MetricType_COUNTER},
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		{labels: labelMap{"upstream_host": "foo", "slot_name": "bar", "status": "starting"}, value: 5, metricType: dto.MetricType_GAUGE},
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	}
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	convey.Convey("Metrics comparison", t, func() {
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		for _, expect := range expected {
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			m := readMetric(<-ch)
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			convey.So(expect, convey.ShouldResemble, m)
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		}
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	})
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	if err := mock.ExpectationsWereMet(); err != nil {
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		t.Errorf("there were unfulfilled exceptions: %s", err)
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	}
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}
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