fix missing-initialization bug

addresses #20

Signed-off-by: Tim Bray <tbray@textuality.com>

internal/keyfinder.go

@@ -89,6 +89,7 @@ func (kf *keyFinder) getKey(record []byte) ([]byte, error) {
 			field++
 		}
 	} else {
+		kf.key = kf.key[:0]
 		allFields := kf.separator.Split(string(record), -1)
 		for i, field := range kf.fields {
 			if int(field) >= len(allFields) {

internal/keyfinder_test.go

@@ -2,6 +2,7 @@ package topfew
 
 import (
 	"bytes"
+	"os"
 	"testing"
 )
 
@@ -35,6 +36,36 @@ func TestFieldSeparator(t *testing.T) {
 	}
 }
 
+func TestCSVSeparator(t *testing.T) {
+	args := []string{"-p", ",", "-f", "11"}
+	c, err := Configure(args)
+	if err != nil {
+		t.Error("Config!")
+	}
+	input, err := os.Open("../test/data/csoc.csv")
+	if err != nil {
+		t.Error("Open: " + err.Error())
+	}
+	counts, err := Run(c, input)
+	if err != nil {
+		t.Error("Run: " + err.Error())
+	}
+	if len(counts) != 5 {
+		t.Errorf("Got %d results, wanted 5", len(counts))
+	}
+	wantCounts := []uint64{4, 2, 1, 1, 1}
+	wantKeys := []string{"50", "-1.97", "amount", "-1.75", "-1.9"}
+	for i, count := range counts {
+		if *count.Count != wantCounts[i] {
+			t.Errorf("Counts[%d] is %d wanted %d", i, *count.Count, wantCounts[i])
+		}
+		// because for equal values, the sort isn't stable - Counts[2,3,4] are all 1
+		if i < 2 && count.Key != wantKeys[i] {
+			t.Errorf("Keys[%d] is %s wanted %s", i, count.Key, wantKeys[i])
+		}
+	}
+}
+
 func TestKeyFinder(t *testing.T) {
 	var records = []string{
 		"a x c",