get-zones output should work as input into preview (#688)

* Add tests for get-zones
* fix CAA, SSHFP, TLSA and other bugs
* New format for get-zones: "djs" which is js but uses "disco commas"
* Print diffs using github.com/andreyvit/diff

Co-authored-by: Tom Limoncelli <tlimoncelli@stackoverflow.com>

commands/gz_test.go

@@ -0,0 +1,80 @@
+package commands
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"testing"
+
+	"github.com/andreyvit/diff"
+
+	_ "github.com/StackExchange/dnscontrol/v2/providers/_all"
+)
+
+func TestFormatTypes(t *testing.T) {
+	/*
+	  Input:                   Converted to:   Should match contents of:
+	  test_data/$DOMAIN.zone   js              test_data/$DOMAIN.zone.js
+	  test_data/$DOMAIN.zone   tsv             test_data/$DOMAIN.zone.tsv
+	  test_data/$DOMAIN.zone   zone            test_data/$DOMAIN.zone.zone
+	*/
+
+	for _, domain := range []string{"simple.com", "example.org"} {
+		t.Run(domain+"/js", func(t *testing.T) { testFormat(t, domain, "js") })
+		t.Run(domain+"/tsv", func(t *testing.T) { testFormat(t, domain, "tsv") })
+		t.Run(domain+"/zone", func(t *testing.T) { testFormat(t, domain, "zone") })
+	}
+}
+
+func testFormat(t *testing.T, domain, format string) {
+	t.Helper()
+
+	expectedFilename := fmt.Sprintf("test_data/%s.zone.%s", domain, format)
+	outputFiletmpl := fmt.Sprintf("%s.zone.%s.*.txt", domain, format)
+
+	outfile, err := ioutil.TempFile("", outputFiletmpl)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.Remove(outfile.Name())
+
+	// Convert test data to the experiment output.
+	gzargs := GetZoneArgs{
+		ZoneNames:    []string{domain},
+		OutputFormat: format,
+		OutputFile:   outfile.Name(),
+		CredName:     "bind",
+		ProviderName: "BIND",
+	}
+	gzargs.CredsFile = "test_data/creds.json"
+
+	// Read the zonefile and convert
+	err = GetZone(gzargs)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Read the actual result:
+	got, err := ioutil.ReadFile(outfile.Name())
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Read the expected result
+	want, err := ioutil.ReadFile(expectedFilename)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	//	// Update got -> want
+	//	err = ioutil.WriteFile(expectedFilename, got, 0644)
+	//	if err != nil {
+	//		log.Fatal(err)
+	//	}
+
+	if w, g := string(want), string(got); w != g {
+		t.Errorf("testFormat mismatch (-got +want):\n%s", diff.LineDiff(g, w))
+	}
+
+}