Eliminate bqiface and complete test coverage in query package (#22)

* Add complete unit tests
* Remove local bqiface package
* Move bigQueryImpl.Query to query package

Author: stephen-soltesz

query/bigquery_runner.go

@@ -4,15 +4,40 @@
 package query
 
 import (
+	"context"
 	"math"
 	"sort"
 	"strings"
 
 	"cloud.google.com/go/bigquery"
-	"github.com/m-lab/prometheus-bigquery-exporter/query/bqiface"
+	"github.com/GoogleCloudPlatform/google-cloud-go-testing/bigquery/bqiface"
 	"github.com/m-lab/prometheus-bigquery-exporter/sql"
+	"google.golang.org/api/iterator"
 )
 
+type bigQueryImpl struct {
+	bqiface.Client
+}
+
+func (b *bigQueryImpl) Query(query string, visit func(row map[string]bigquery.Value) error) error {
+	q := b.Client.Query(query)
+	it, err := q.Read(context.Background())
+	if err != nil {
+		return err
+	}
+	var row map[string]bigquery.Value
+	for err = it.Next(&row); err == nil; err = it.Next(&row) {
+		err2 := visit(row)
+		if err2 != nil {
+			return err2
+		}
+	}
+	if err != iterator.Done {
+		return err
+	}
+	return nil
+}
+
 // BQRunner is a concerete implementation of QueryRunner for BigQuery.
 type BQRunner struct {
 	runner runner
@@ -26,8 +51,8 @@ type runner interface {
 // NewBQRunner creates a new QueryRunner instance.
 func NewBQRunner(client *bigquery.Client) *BQRunner {
 	return &BQRunner{
-		runner: &bqiface.BigQueryImpl{
-			Client: client,
+		runner: &bigQueryImpl{
+			Client: bqiface.AdaptClient(client),
 		},
 	}
 }

query/bigquery_runner_test.go

@@ -8,6 +8,8 @@ import (
 
 	"cloud.google.com/go/bigquery"
 	"github.com/m-lab/prometheus-bigquery-exporter/sql"
+
+	"github.com/m-lab/go/cloud/bqfake"
 )
 
 func TestRowToMetric(t *testing.T) {
@@ -164,3 +166,64 @@ func TestBQRunner_Query(t *testing.T) {
 func TestNewBQRunner(t *testing.T) {
 	NewBQRunner(nil)
 }
+
+func TestBigQueryImpl_Query(t *testing.T) {
+	tests := []struct {
+		name    string
+		config  bqfake.QueryConfig
+		query   string
+		visit   func(row map[string]bigquery.Value) error
+		wantErr bool
+	}{
+		{
+			name: "success-iteration",
+			config: bqfake.QueryConfig{
+				RowIteratorConfig: bqfake.RowIteratorConfig{
+					Rows: []map[string]bigquery.Value{{"value": 1.234}},
+				},
+			},
+			visit: func(row map[string]bigquery.Value) error {
+				return nil
+			},
+		},
+		{
+			name: "visit-error",
+			config: bqfake.QueryConfig{
+				RowIteratorConfig: bqfake.RowIteratorConfig{
+					Rows: []map[string]bigquery.Value{{"value": 1.234}},
+				},
+			},
+			visit: func(row map[string]bigquery.Value) error {
+				return fmt.Errorf("Fake visit error")
+			},
+			wantErr: true,
+		},
+		{
+			name: "read-error",
+			config: bqfake.QueryConfig{
+				ReadErr: fmt.Errorf("This is a fake read error"),
+			},
+			wantErr: true,
+		},
+		{
+			name: "iterator-error",
+			config: bqfake.QueryConfig{
+				RowIteratorConfig: bqfake.RowIteratorConfig{
+					IterErr: fmt.Errorf("This is a fake iterator error"),
+				},
+			},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			client := bqfake.NewQueryReadClient(tt.config)
+			b := &bigQueryImpl{
+				Client: client,
+			}
+			if err := b.Query(tt.query, tt.visit); (err != nil) != tt.wantErr {
+				t.Errorf("bigQueryImpl.Query() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}