diff --git a/exif-read-tool/main.go b/exif-read-tool/main.go
index ce4a79f..aeb790f 100644
--- a/exif-read-tool/main.go
+++ b/exif-read-tool/main.go
@@ -1,3 +1,16 @@
+// This tool dumps EXIF information from images.
+//
+// Example command-line:
+//
+//   exif-read-tool -filepath <file-path>
+//
+// Example Output:
+//
+//   IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x010f) NAME=[Make] COUNT=(6) TYPE=[ASCII] VALUE=[Canon]
+//   IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0110) NAME=[Model] COUNT=(22) TYPE=[ASCII] VALUE=[Canon EOS 5D Mark III]
+//   IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0112) NAME=[Orientation] COUNT=(1) TYPE=[SHORT] VALUE=[1]
+//   IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x011a) NAME=[XResolution] COUNT=(1) TYPE=[RATIONAL] VALUE=[72/1]
+//   ...
 package main
 
 import (
@@ -56,7 +69,7 @@ func main() {
     // Run the parse.
 
     ti := exif.NewTagIndex()
-    visitor := func(indexedIfdName string, tagId uint16, tagType exif.TagType, valueContext exif.ValueContext) (err error) {
+    visitor := func(ii exif.IfdIdentity, ifdIndex int, tagId uint16, tagType exif.TagType, valueContext exif.ValueContext) (err error) {
         defer func() {
             if state := recover(); state != nil {
                 err = log.Wrap(state.(error))
@@ -64,10 +77,10 @@ func main() {
             }
         }()
 
-        it, err := ti.Get(indexedIfdName, tagId)
+        it, err := ti.Get(ii, tagId)
         if err != nil {
             if log.Is(err, exif.ErrTagNotFound) {
-                fmt.Printf("WARNING: Unknown tag: [%s] (%04x)\n", indexedIfdName, tagId)
+                fmt.Printf("WARNING: Unknown tag: [%s] (%04x)\n", ii, tagId)
                 return nil
             } else {
                 log.Panic(err)
@@ -76,7 +89,7 @@ func main() {
 
         valueString := ""
         if tagType.Type() == exif.TypeUndefined {
-            value, err := exif.UndefinedValue(indexedIfdName, tagId, valueContext, tagType.ByteOrder())
+            value, err := exif.UndefinedValue(ii, tagId, valueContext, tagType.ByteOrder())
             if log.Is(err, exif.ErrUnhandledUnknownTypedTag) {
                 valueString = "!UNDEFINED!"
             } else if err != nil {
@@ -89,10 +102,10 @@ func main() {
             log.PanicIf(err)
         }
 
-        fmt.Printf("IFD=[%s] ID=(0x%04x) NAME=[%s] COUNT=(%d) TYPE=[%s] VALUE=[%s]\n", indexedIfdName, tagId, it.Name, valueContext.UnitCount, tagType.Name(), valueString)
+        fmt.Printf("IFD=[%s] ID=(0x%04x) NAME=[%s] COUNT=(%d) TYPE=[%s] VALUE=[%s]\n", ii, tagId, it.Name, valueContext.UnitCount, tagType.Name(), valueString)
         return nil
     }
 
-    err = e.Visit(data[foundAt:], visitor)
+    _, err = e.Visit(data[foundAt:], visitor)
     log.PanicIf(err)
 }
diff --git a/exif-read-tool/main_test.go b/exif-read-tool/main_test.go
new file mode 100644
index 0000000..f7e1dac
--- /dev/null
+++ b/exif-read-tool/main_test.go
@@ -0,0 +1,113 @@
+package main
+
+import (
+    "testing"
+    "os"
+    "path"
+    "bytes"
+    "fmt"
+
+    "os/exec"
+
+    "github.com/dsoprea/go-logging"
+)
+
+var (
+    assetsPath = ""
+    appFilepath = ""
+)
+
+func TestMain(t *testing.T) {
+    imageFilepath := path.Join(assetsPath, "NDM_8901.jpg")
+
+    cmd := exec.Command(
+            "go", "run", appFilepath,
+            "-filepath", imageFilepath)
+
+    b := new(bytes.Buffer)
+    cmd.Stdout = b
+    cmd.Stderr = b
+
+    err := cmd.Run()
+    actual := b.String()
+
+    if err != nil {
+        fmt.Printf(actual)
+        log.Panic(err)
+    }
+
+    expected := `IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x010f) NAME=[Make] COUNT=(6) TYPE=[ASCII] VALUE=[Canon]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0110) NAME=[Model] COUNT=(22) TYPE=[ASCII] VALUE=[Canon EOS 5D Mark III]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0112) NAME=[Orientation] COUNT=(1) TYPE=[SHORT] VALUE=[1]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x011a) NAME=[XResolution] COUNT=(1) TYPE=[RATIONAL] VALUE=[72/1]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x011b) NAME=[YResolution] COUNT=(1) TYPE=[RATIONAL] VALUE=[72/1]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0128) NAME=[ResolutionUnit] COUNT=(1) TYPE=[SHORT] VALUE=[2]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0132) NAME=[DateTime] COUNT=(20) TYPE=[ASCII] VALUE=[2017:12:02 08:18:50]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x013b) NAME=[Artist] COUNT=(1) TYPE=[ASCII] VALUE=[]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0213) NAME=[YCbCrPositioning] COUNT=(1) TYPE=[SHORT] VALUE=[2]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x8298) NAME=[Copyright] COUNT=(1) TYPE=[ASCII] VALUE=[]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x8769) NAME=[ExifTag] COUNT=(1) TYPE=[LONG] VALUE=[360]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x829a) NAME=[ExposureTime] COUNT=(1) TYPE=[RATIONAL] VALUE=[1/640]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x829d) NAME=[FNumber] COUNT=(1) TYPE=[RATIONAL] VALUE=[4/1]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x8822) NAME=[ExposureProgram] COUNT=(1) TYPE=[SHORT] VALUE=[4]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x8827) NAME=[ISOSpeedRatings] COUNT=(1) TYPE=[SHORT] VALUE=[1600]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x8830) NAME=[SensitivityType] COUNT=(1) TYPE=[SHORT] VALUE=[2]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x8832) NAME=[RecommendedExposureIndex] COUNT=(1) TYPE=[LONG] VALUE=[1600]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9000) NAME=[ExifVersion] COUNT=(4) TYPE=[UNDEFINED] VALUE=[0230]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9003) NAME=[DateTimeOriginal] COUNT=(20) TYPE=[ASCII] VALUE=[2017:12:02 08:18:50]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9004) NAME=[DateTimeDigitized] COUNT=(20) TYPE=[ASCII] VALUE=[2017:12:02 08:18:50]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9101) NAME=[ComponentsConfiguration] COUNT=(4) TYPE=[UNDEFINED] VALUE=[ComponentsConfiguration<ID=[YCBCR] BYTES=[1 2 3 0]>]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9201) NAME=[ShutterSpeedValue] COUNT=(1) TYPE=[SRATIONAL] VALUE=[614400/65536]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9202) NAME=[ApertureValue] COUNT=(1) TYPE=[RATIONAL] VALUE=[262144/65536]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9204) NAME=[ExposureBiasValue] COUNT=(1) TYPE=[SRATIONAL] VALUE=[0/1]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9207) NAME=[MeteringMode] COUNT=(1) TYPE=[SHORT] VALUE=[5]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9209) NAME=[Flash] COUNT=(1) TYPE=[SHORT] VALUE=[16]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x920a) NAME=[FocalLength] COUNT=(1) TYPE=[RATIONAL] VALUE=[16/1]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x927c) NAME=[MakerNote] COUNT=(8152) TYPE=[UNDEFINED] VALUE=[MakerNote<TYPE-ID=[28 00 01 00 03 00 31 00 00 00 74 05 00 00 02 00 03 00 04 00]>]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9286) NAME=[UserComment] COUNT=(264) TYPE=[UNDEFINED] VALUE=[UserComment<ENCODING=[UNDEFINED] V=[]>]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9290) NAME=[SubSecTime] COUNT=(3) TYPE=[ASCII] VALUE=[00]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9291) NAME=[SubSecTimeOriginal] COUNT=(3) TYPE=[ASCII] VALUE=[00]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0x9292) NAME=[SubSecTimeDigitized] COUNT=(3) TYPE=[ASCII] VALUE=[00]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa000) NAME=[FlashpixVersion] COUNT=(4) TYPE=[UNDEFINED] VALUE=[0100]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa001) NAME=[ColorSpace] COUNT=(1) TYPE=[SHORT] VALUE=[1]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa002) NAME=[PixelXDimension] COUNT=(1) TYPE=[SHORT] VALUE=[3840]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa003) NAME=[PixelYDimension] COUNT=(1) TYPE=[SHORT] VALUE=[2560]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa005) NAME=[InteroperabilityTag] COUNT=(1) TYPE=[LONG] VALUE=[9326]
+IFD=[IfdIdentity<PARENT-NAME=[Exif] NAME=[Iop]>] ID=(0x0001) NAME=[InteroperabilityIndex] COUNT=(4) TYPE=[ASCII] VALUE=[R98]
+IFD=[IfdIdentity<PARENT-NAME=[Exif] NAME=[Iop]>] ID=(0x0002) NAME=[InteroperabilityVersion] COUNT=(4) TYPE=[UNDEFINED] VALUE=[0100]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa20e) NAME=[FocalPlaneXResolution] COUNT=(1) TYPE=[RATIONAL] VALUE=[3840000/1461]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa20f) NAME=[FocalPlaneYResolution] COUNT=(1) TYPE=[RATIONAL] VALUE=[2560000/972]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa210) NAME=[FocalPlaneResolutionUnit] COUNT=(1) TYPE=[SHORT] VALUE=[2]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa401) NAME=[CustomRendered] COUNT=(1) TYPE=[SHORT] VALUE=[0]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa402) NAME=[ExposureMode] COUNT=(1) TYPE=[SHORT] VALUE=[0]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa403) NAME=[WhiteBalance] COUNT=(1) TYPE=[SHORT] VALUE=[0]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa406) NAME=[SceneCaptureType] COUNT=(1) TYPE=[SHORT] VALUE=[0]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa430) NAME=[CameraOwnerName] COUNT=(1) TYPE=[ASCII] VALUE=[]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa431) NAME=[BodySerialNumber] COUNT=(13) TYPE=[ASCII] VALUE=[063024020097]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa432) NAME=[LensSpecification] COUNT=(4) TYPE=[RATIONAL] VALUE=[16/1]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa434) NAME=[LensModel] COUNT=(22) TYPE=[ASCII] VALUE=[EF16-35mm f/4L IS USM]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[Exif]>] ID=(0xa435) NAME=[LensSerialNumber] COUNT=(11) TYPE=[ASCII] VALUE=[2400001068]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x8825) NAME=[GPSTag] COUNT=(1) TYPE=[LONG] VALUE=[9554]
+IFD=[IfdIdentity<PARENT-NAME=[IFD] NAME=[GPSInfo]>] ID=(0x0000) NAME=[GPSVersionID] COUNT=(4) TYPE=[BYTE] VALUE=[2]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0103) NAME=[Compression] COUNT=(1) TYPE=[SHORT] VALUE=[6]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x011a) NAME=[XResolution] COUNT=(1) TYPE=[RATIONAL] VALUE=[72/1]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x011b) NAME=[YResolution] COUNT=(1) TYPE=[RATIONAL] VALUE=[72/1]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0128) NAME=[ResolutionUnit] COUNT=(1) TYPE=[SHORT] VALUE=[2]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0201) NAME=[JPEGInterchangeFormat] COUNT=(1) TYPE=[LONG] VALUE=[11444]
+IFD=[IfdIdentity<PARENT-NAME=[] NAME=[IFD]>] ID=(0x0202) NAME=[JPEGInterchangeFormatLength] COUNT=(1) TYPE=[LONG] VALUE=[21491]
+`
+
+    if actual != expected {
+        t.Fatalf("Output not as expected:\n%s", actual)
+    }
+}
+
+func init() {
+    goPath := os.Getenv("GOPATH")
+    if goPath == "" {
+        log.Panicf("GOPATH is empty")
+    }
+
+    assetsPath = path.Join(goPath, "src", "github.com", "dsoprea", "go-exif", "assets")
+    appFilepath = path.Join(goPath, "src", "github.com", "dsoprea", "go-exif", "exif-read-tool", "main.go")
+}