Make report.readFileStat as stat.NewPGresultFile.

internal/stat/postgres.go

@@ -3,9 +3,11 @@ package stat
 import (
 	"bytes"
 	"database/sql"
+	"encoding/json"
 	"fmt"
 	"github.com/lesovsky/pgcenter/internal/postgres"
 	"github.com/lesovsky/pgcenter/internal/query"
+	"io"
 	"sort"
 	"strconv"
 	"strings"
@@ -224,6 +226,24 @@ func NewPGresultQuery(db *postgres.DB, query string) (PGresult, error) {
 	}, nil
 }
 
+// NewPGresultFile creates PGresult using reader interface.
+func NewPGresultFile(r io.Reader, bufsz int64) (PGresult, error) {
+	data := make([]byte, bufsz)
+
+	if _, err := io.ReadFull(r, data); err != nil {
+		return PGresult{}, err
+	}
+
+	// initialize an empty struct and unmarshal data from the buffer
+	res := PGresult{}
+	err := json.Unmarshal(data, &res)
+	if err != nil {
+		return PGresult{}, err
+	}
+
+	return res, nil
+}
+
 // Compare is public wrapper around calculateDelta.
 func Compare(curr, prev PGresult, itv int, interval [2]int, skey int, desc bool, ukey int) (PGresult, error) {
 	return calculateDelta(curr, prev, itv, interval, skey, desc, ukey)

internal/stat/postgres_test.go

@@ -1,12 +1,15 @@
 package stat
 
 import (
+	"archive/tar"
 	"bytes"
 	"database/sql"
 	"fmt"
 	"github.com/lesovsky/pgcenter/internal/postgres"
 	"github.com/lesovsky/pgcenter/internal/query"
 	"github.com/stretchr/testify/assert"
+	"io"
+	"os"
 	"testing"
 )
 
@@ -138,6 +141,44 @@ func TestNewPGresultQuery(t *testing.T) {
 	assert.Error(t, err)
 }
 
+func Test_NewPGresultFile(t *testing.T) {
+	testcases := []struct {
+		valid    bool
+		filename string
+	}{
+		{valid: true, filename: "testdata/pgcenter.stat.golden.tar"},
+		{valid: false, filename: "testdata/pgcenter.stat.invalid.tar"},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.filename, func(t *testing.T) {
+			f, err := os.Open(tc.filename)
+			assert.NoError(t, err)
+
+			r := tar.NewReader(f)
+
+			for {
+				hdr, err := r.Next()
+				if err == io.EOF {
+					break
+				} else if err != nil {
+					assert.Fail(t, "unexpected error", err)
+				}
+
+				got, err := NewPGresultFile(r, hdr.Size)
+				if tc.valid {
+					assert.NoError(t, err)
+					assert.NotNil(t, got.Values)
+					assert.NotNil(t, got.Cols)
+				} else {
+					assert.Error(t, err)
+					assert.Equal(t, PGresult{}, got)
+				}
+			}
+		})
+	}
+}
+
 func Test_calculateDelta(t *testing.T) {
 	prev := PGresult{
 		Valid: true, Ncols: 4, Nrows: 4, Cols: []string{"unique", "col2", "col3", "col4"},

report/report.go

@@ -2,7 +2,6 @@ package report
 
 import (
 	"archive/tar"
-	"encoding/json"
 	"fmt"
 	"github.com/lesovsky/pgcenter/internal/align"
 	"github.com/lesovsky/pgcenter/internal/stat"
@@ -121,7 +120,7 @@ func (app *app) doReport(r *tar.Reader) error {
 		}
 
 		// Read stats from file.
-		currStat, err := readFileStat(r, hdr.Size)
+		currStat, err := stat.NewPGresultFile(r, hdr.Size)
 		if err != nil {
 			return err
 		}
@@ -227,24 +226,6 @@ func isFilenameTimestampOK(name string, start, end time.Time) (time.Time, error)
 	return ts, nil
 }
 
-// readFileStat reads content of tar file, unmarshal data and return stat object.
-func readFileStat(r *tar.Reader, bufsz int64) (stat.PGresult, error) {
-	data := make([]byte, bufsz)
-
-	if _, err := io.ReadFull(r, data); err != nil {
-		return stat.PGresult{}, err
-	}
-
-	// initialize an empty struct and unmarshal data from the buffer
-	res := stat.PGresult{}
-	err := json.Unmarshal(data, &res)
-	if err != nil {
-		return stat.PGresult{}, err
-	}
-
-	return res, nil
-}
-
 // countDiff compares two stat samples and produce differential sample.
 func countDiff(curr, prev stat.PGresult, interval int, v view.View) (stat.PGresult, error) {
 	var diff stat.PGresult

report/report_test.go

@@ -211,44 +211,6 @@ func Test_isFilenameTimestampOK(t *testing.T) {
 	}
 }
 
-func Test_readFileStat(t *testing.T) {
-	testcases := []struct {
-		valid    bool
-		filename string
-	}{
-		{valid: true, filename: "testdata/pgcenter.stat.golden.tar"},
-		{valid: false, filename: "testdata/pgcenter.stat.invalid.tar"},
-	}
-
-	for _, tc := range testcases {
-		t.Run(tc.filename, func(t *testing.T) {
-			f, err := os.Open(tc.filename)
-			assert.NoError(t, err)
-
-			r := tar.NewReader(f)
-
-			for {
-				hdr, err := r.Next()
-				if err == io.EOF {
-					break
-				} else if err != nil {
-					assert.Fail(t, "unexpected error", err)
-				}
-
-				got, err := readFileStat(r, hdr.Size)
-				if tc.valid {
-					assert.NoError(t, err)
-					assert.NotNil(t, got.Values)
-					assert.NotNil(t, got.Cols)
-				} else {
-					assert.Error(t, err)
-					assert.Equal(t, stat.PGresult{}, got)
-				}
-			}
-		})
-	}
-}
-
 func Test_countDiff(t *testing.T) {
 	prev := stat.PGresult{
 		Valid: true, Ncols: 18, Nrows: 1,