Fix listing drive docs at root - fixes #336

* Remove full drive list code
    * it is slower and uses more data
    * having two directory listing routines is causing problems (including this one)
    * less code is more
  * Make sure we don't recurse into directories we don't own
  * Fix export extension handling and add tests

drive/drive_internal_test.go

@@ -0,0 +1,59 @@
+package drive
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/api/drive/v2"
+)
+
+func TestInternalParseExtensions(t *testing.T) {
+	for _, test := range []struct {
+		in      string
+		want    []string
+		wantErr error
+	}{
+		{"doc", []string{"doc"}, nil},
+		{" docx ,XLSX, 	pptx,svg", []string{"docx", "xlsx", "pptx", "svg"}, nil},
+		{"docx,svg,Docx", []string{"docx", "svg"}, nil},
+		{"docx,potato,docx", []string{"docx"}, fmt.Errorf(`Couldn't find mime type for extension "potato"`)},
+	} {
+		f := new(Fs)
+		gotErr := f.parseExtensions(test.in)
+		assert.Equal(t, test.wantErr, gotErr)
+		assert.Equal(t, test.want, f.extensions)
+	}
+
+	// Test it is appending
+	f := new(Fs)
+	assert.Nil(t, f.parseExtensions("docx,svg"))
+	assert.Nil(t, f.parseExtensions("docx,svg,xlsx"))
+	assert.Equal(t, []string{"docx", "svg", "xlsx"}, f.extensions)
+
+}
+
+func TestInternalFindExportFormat(t *testing.T) {
+	item := new(drive.File)
+	item.ExportLinks = map[string]string{
+		"application/pdf": "http://pdf",
+		"application/rtf": "http://rtf",
+	}
+	for _, test := range []struct {
+		extensions    []string
+		wantExtension string
+		wantLink      string
+	}{
+		{[]string{}, "", ""},
+		{[]string{"pdf"}, "pdf", "http://pdf"},
+		{[]string{"pdf", "rtf", "xls"}, "pdf", "http://pdf"},
+		{[]string{"xls", "rtf", "pdf"}, "rtf", "http://rtf"},
+		{[]string{"xls", "csv", "svg"}, "", ""},
+	} {
+		f := new(Fs)
+		f.extensions = test.extensions
+		gotExtension, gotLink := f.findExportFormat("file", item)
+		assert.Equal(t, test.wantExtension, gotExtension)
+		assert.Equal(t, test.wantLink, gotLink)
+	}
+}