coder · cmoog · Mar 10, 2021 · Mar 10, 2021
diff --git a/pkg/tablewriter/table_output.golden b/pkg/tablewriter/table_output.golden
@@ -0,0 +1,3 @@
+Name     birthday month    first_nested     second_nested      Age      
+Tom      12                234-0934         2340-234234        28.12    
+Jerry    3                 aflfafe-afjlk    falj-fjlkjlkadf    36.22    
diff --git a/pkg/tablewriter/tablewriter.go b/pkg/tablewriter/tablewriter.go
@@ -2,6 +2,7 @@ package tablewriter
 
 import (
 	"fmt"
+	"io"
 	"os"
 	"reflect"
 	"strings"
@@ -22,7 +23,7 @@ func StructValues(data interface{}) string {
 			continue
 		}
 		if shouldFlatten(v.Type().Field(i)) {
-			fmt.Fprintf(s, "%v\t", StructValues(v.Field(i).Interface()))
+			fmt.Fprintf(s, "%v", StructValues(v.Field(i).Interface()))
 			continue
 		}
 		fmt.Fprintf(s, "%v\t", v.Field(i).Interface())
@@ -46,14 +47,17 @@ func StructFieldNames(data interface{}) string {
 			continue
 		}
 		if shouldFlatten(field) {
-			fmt.Fprintf(s, "%s\t", StructFieldNames(reflect.New(field.Type).Interface()))
+			fmt.Fprintf(s, "%s", StructFieldNames(reflect.New(field.Type).Interface()))
 			continue
 		}
 		fmt.Fprintf(s, "%s\t", fieldName(field))
 	}
 	return s.String()
 }
 
+// The output io.Writer for WriteTable. This is globally defined to allow overriding in tests.
+var tableOutput io.Writer = os.Stdout
+
 // WriteTable writes the given list elements to stdout in a human readable
 // tabular format. Headers abide by the `table` struct tag.
 //
@@ -63,7 +67,7 @@ func WriteTable(length int, each func(i int) interface{}) error {
 	if length < 1 {
 		return nil
 	}
-	w := tabwriter.NewWriter(os.Stdout, 0, 0, 4, ' ', 0)
+	w := tabwriter.NewWriter(tableOutput, 0, 0, 4, ' ', 0)
 	defer func() { _ = w.Flush() }() // Best effort.
 	for ix := 0; ix < length; ix++ {
 		item := each(ix)

diff --git a/pkg/tablewriter/tablewriter_test.go b/pkg/tablewriter/tablewriter_test.go
@@ -0,0 +1,68 @@
+package tablewriter
+
+import (
+	"bytes"
+	"flag"
+	"io/ioutil"
+	"testing"
+
+	"cdr.dev/slog/sloggers/slogtest/assert"
+)
+
+var write = flag.Bool("write", false, "write to the golden files")
+
+func TestTableWriter(t *testing.T) {
+	type NestedRow struct {
+		NestedOne string `table:"first_nested"`
+		NestedTwo string `table:"second_nested"`
+	}
+
+	type Row struct {
+		ID            string `table:"-"`
+		Name          string
+		BirthdayMonth int       `table:"birthday month"`
+		Nested        NestedRow `table:"_"`
+		Age           float32
+	}
+
+	items := []Row{
+		{
+			ID:            "13123lkjqlkj-2f323l--f23f",
+			Name:          "Tom",
+			BirthdayMonth: 12,
+			Age:           28.12,
+			Nested: NestedRow{
+				NestedOne: "234-0934",
+				NestedTwo: "2340-234234",
+			},
+		},
+		{
+			ID:            "afwaflkj23kl-2f323l--f23f",
+			Name:          "Jerry",
+			BirthdayMonth: 3,
+			Age:           36.22,
+			Nested: NestedRow{
+				NestedOne: "aflfafe-afjlk",
+				NestedTwo: "falj-fjlkjlkadf",
+			},
+		},
+	}
+
+	buf := bytes.NewBuffer(nil)
+	tableOutput = buf
+	err := WriteTable(len(items), func(i int) interface{} { return items[i] })
+	assert.Success(t, "write table", err)
+
+	assertGolden(t, "table_output.golden", buf.Bytes())
+}
+
+func assertGolden(t *testing.T, path string, output []byte) {
+	if *write {
+		err := ioutil.WriteFile(path, output, 0777)
+		assert.Success(t, "write file", err)
+		return
+	}
+	goldenContent, err := ioutil.ReadFile(path)
+	assert.Success(t, "read golden file", err)
+	assert.Equal(t, "golden content matches", string(goldenContent), string(output))
+}