@@ -21,8 +21,8 @@ var builtinAllowedBuildArgs = map[string]bool{

 	"no_proxy":    true,

 }

-// buildArgs manages arguments used by the builder

-type buildArgs struct {

+// BuildArgs manages arguments used by the builder

+type BuildArgs struct {

 	// args that are allowed for expansion/substitution and passing to commands in 'run'.

 	allowedBuildArgs map[string]*string

 	// args defined before the first `FROM` in a Dockerfile

@@ -33,8 +33,9 @@ type buildArgs struct {

 	argsFromOptions map[string]*string

 }

-func newBuildArgs(argsFromOptions map[string]*string) *buildArgs {

-	return &buildArgs{

+// NewBuildArgs creates a new BuildArgs type

+func NewBuildArgs(argsFromOptions map[string]*string) *BuildArgs {

+	return &BuildArgs{

 		allowedBuildArgs: make(map[string]*string),

 		allowedMetaArgs:  make(map[string]*string),

 		referencedArgs:   make(map[string]struct{}),

@@ -42,8 +43,9 @@ func newBuildArgs(argsFromOptions map[string]*string) *buildArgs {

 	}

 }

-func (b *buildArgs) Clone() *buildArgs {

-	result := newBuildArgs(b.argsFromOptions)

+// Clone returns a copy of the BuildArgs type

+func (b *BuildArgs) Clone() *BuildArgs {

+	result := NewBuildArgs(b.argsFromOptions)

 	for k, v := range b.allowedBuildArgs {

 		result.allowedBuildArgs[k] = v

 	}

@@ -56,7 +58,9 @@ func (b *buildArgs) Clone() *buildArgs {

 	return result

 }

-func (b *buildArgs) MergeReferencedArgs(other *buildArgs) {

+// MergeReferencedArgs merges referenced args from another BuildArgs

+// object into the current one

+func (b *BuildArgs) MergeReferencedArgs(other *BuildArgs) {

 	for k := range other.referencedArgs {

 		b.referencedArgs[k] = struct{}{}

 	}

@@ -64,7 +68,7 @@ func (b *buildArgs) MergeReferencedArgs(other *buildArgs) {

 // WarnOnUnusedBuildArgs checks if there are any leftover build-args that were

 // passed but not consumed during build. Print a warning, if there are any.

-func (b *buildArgs) WarnOnUnusedBuildArgs(out io.Writer) {

+func (b *BuildArgs) WarnOnUnusedBuildArgs(out io.Writer) {

 	leftoverArgs := []string{}

 	for arg := range b.argsFromOptions {

 		_, isReferenced := b.referencedArgs[arg]

@@ -80,17 +84,17 @@ func (b *buildArgs) WarnOnUnusedBuildArgs(out io.Writer) {

 // ResetAllowed clears the list of args that are allowed to be used by a

 // directive

-func (b *buildArgs) ResetAllowed() {

+func (b *BuildArgs) ResetAllowed() {

 	b.allowedBuildArgs = make(map[string]*string)

 }

 // AddMetaArg adds a new meta arg that can be used by FROM directives

-func (b *buildArgs) AddMetaArg(key string, value *string) {

+func (b *BuildArgs) AddMetaArg(key string, value *string) {

 	b.allowedMetaArgs[key] = value

 }

 // AddArg adds a new arg that can be used by directives

-func (b *buildArgs) AddArg(key string, value *string) {

+func (b *BuildArgs) AddArg(key string, value *string) {

 	b.allowedBuildArgs[key] = value

 	b.referencedArgs[key] = struct{}{}

 }

@@ -98,23 +102,23 @@ func (b *buildArgs) AddArg(key string, value *string) {

 // IsReferencedOrNotBuiltin checks if the key is a built-in arg, or if it has been

 // referenced by the Dockerfile. Returns true if the arg is not a builtin or

 // if the builtin has been referenced in the Dockerfile.

-func (b *buildArgs) IsReferencedOrNotBuiltin(key string) bool {

+func (b *BuildArgs) IsReferencedOrNotBuiltin(key string) bool {

 	_, isBuiltin := builtinAllowedBuildArgs[key]

 	_, isAllowed := b.allowedBuildArgs[key]

 	return isAllowed || !isBuiltin

 }

 // GetAllAllowed returns a mapping with all the allowed args

-func (b *buildArgs) GetAllAllowed() map[string]string {

+func (b *BuildArgs) GetAllAllowed() map[string]string {

 	return b.getAllFromMapping(b.allowedBuildArgs)

 }

 // GetAllMeta returns a mapping with all the meta meta args

-func (b *buildArgs) GetAllMeta() map[string]string {

+func (b *BuildArgs) GetAllMeta() map[string]string {

 	return b.getAllFromMapping(b.allowedMetaArgs)

 }

-func (b *buildArgs) getAllFromMapping(source map[string]*string) map[string]string {

+func (b *BuildArgs) getAllFromMapping(source map[string]*string) map[string]string {

 	m := make(map[string]string)

 	keys := keysFromMaps(source, builtinAllowedBuildArgs)

@@ -128,7 +132,7 @@ func (b *buildArgs) getAllFromMapping(source map[string]*string) map[string]stri

 }

 // FilterAllowed returns all allowed args without the filtered args

-func (b *buildArgs) FilterAllowed(filter []string) []string {

+func (b *BuildArgs) FilterAllowed(filter []string) []string {

 	envs := []string{}

 	configEnv := opts.ConvertKVStringsToMap(filter)

@@ -140,7 +144,7 @@ func (b *buildArgs) FilterAllowed(filter []string) []string {

 	return envs

 }

-func (b *buildArgs) getBuildArg(key string, mapping map[string]*string) (string, bool) {

+func (b *BuildArgs) getBuildArg(key string, mapping map[string]*string) (string, bool) {

 	defaultValue, exists := mapping[key]

 	// Return override from options if one is defined

 	if v, ok := b.argsFromOptions[key]; ok && v != nil {

@@ -14,7 +14,7 @@ func strPtr(source string) *string {

 }

 func TestGetAllAllowed(t *testing.T) {

-	buildArgs := newBuildArgs(map[string]*string{

+	buildArgs := NewBuildArgs(map[string]*string{

 		"ArgNotUsedInDockerfile":              strPtr("fromopt1"),

 		"ArgOverriddenByOptions":              strPtr("fromopt2"),

 		"ArgNoDefaultInDockerfileFromOptions": strPtr("fromopt3"),

@@ -45,7 +45,7 @@ func TestGetAllAllowed(t *testing.T) {

 }

 func TestGetAllMeta(t *testing.T) {

-	buildArgs := newBuildArgs(map[string]*string{

+	buildArgs := NewBuildArgs(map[string]*string{

 		"ArgNotUsedInDockerfile":        strPtr("fromopt1"),

 		"ArgOverriddenByOptions":        strPtr("fromopt2"),

 		"ArgNoDefaultInMetaFromOptions": strPtr("fromopt3"),

@@ -67,7 +67,7 @@ func TestGetAllMeta(t *testing.T) {

 }

 func TestWarnOnUnusedBuildArgs(t *testing.T) {

-	buildArgs := newBuildArgs(map[string]*string{

+	buildArgs := NewBuildArgs(map[string]*string{

 		"ThisArgIsUsed":    strPtr("fromopt1"),

 		"ThisArgIsNotUsed": strPtr("fromopt2"),

 		"HTTPS_PROXY":      strPtr("referenced builtin"),

@@ -86,7 +86,7 @@ func TestWarnOnUnusedBuildArgs(t *testing.T) {

 }

 func TestIsUnreferencedBuiltin(t *testing.T) {

-	buildArgs := newBuildArgs(map[string]*string{

+	buildArgs := NewBuildArgs(map[string]*string{

 		"ThisArgIsUsed":    strPtr("fromopt1"),

 		"ThisArgIsNotUsed": strPtr("fromopt2"),

 		"HTTPS_PROXY":      strPtr("referenced builtin"),

@@ -250,7 +250,7 @@ func emitImageID(aux *streamformatter.AuxFormatter, state *dispatchState) error

 	return aux.Emit(types.BuildResult{ID: state.imageID})

 }

-func processMetaArg(meta instructions.ArgCommand, shlex *shell.Lex, args *buildArgs) error {

+func processMetaArg(meta instructions.ArgCommand, shlex *shell.Lex, args *BuildArgs) error {

 	// shell.Lex currently only support the concatenated string format

 	envs := convertMapToEnvList(args.GetAllAllowed())

 	if err := meta.Expand(func(word string) (string, error) {

@@ -271,7 +271,7 @@ func printCommand(out io.Writer, currentCommandIndex int, totalCommands int, cmd

 func (b *Builder) dispatchDockerfileWithCancellation(parseResult []instructions.Stage, metaArgs []instructions.ArgCommand, escapeToken rune, source builder.Source) (*dispatchState, error) {

 	dispatchRequest := dispatchRequest{}

-	buildArgs := newBuildArgs(b.options.BuildArgs)

+	buildArgs := NewBuildArgs(b.options.BuildArgs)

 	totalCommands := len(metaArgs) + len(parseResult)

 	currentCommandIndex := 1

 	for _, stage := range parseResult {

@@ -388,7 +388,7 @@ func BuildFromConfig(config *container.Config, changes []string, os string) (*co

 		commands = append(commands, cmd)

 	}

-	dispatchRequest := newDispatchRequest(b, dockerfile.EscapeToken, nil, newBuildArgs(b.options.BuildArgs), newStagesBuildResults())

+	dispatchRequest := newDispatchRequest(b, dockerfile.EscapeToken, nil, NewBuildArgs(b.options.BuildArgs), newStagesBuildResults())

 	// We make mutations to the configuration, ensure we have a copy

 	dispatchRequest.state.runConfig = copyRunConfig(config)

 	dispatchRequest.state.imageID = config.Image

@@ -399,7 +399,7 @@ func dispatchRun(d dispatchRequest, c *instructions.RunCommand) error {

 // remove any unreferenced built-in args from the environment variables.

 // These args are transparent so resulting image should be the same regardless

 // of the value.

-func prependEnvOnCmd(buildArgs *buildArgs, buildArgVars []string, cmd strslice.StrSlice) strslice.StrSlice {

+func prependEnvOnCmd(buildArgs *BuildArgs, buildArgVars []string, cmd strslice.StrSlice) strslice.StrSlice {

 	var tmpBuildEnv []string

 	for _, env := range buildArgVars {

 		key := strings.SplitN(env, "=", 2)[0]

@@ -41,7 +41,7 @@ func newBuilderWithMockBackend() *Builder {

 func TestEnv2Variables(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '\\', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '\\', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	envCommand := &instructions.EnvCommand{

 		Env: instructions.KeyValuePairs{

 			instructions.KeyValuePair{Key: "var1", Value: "val1"},

@@ -60,7 +60,7 @@ func TestEnv2Variables(t *testing.T) {

 func TestEnvValueWithExistingRunConfigEnv(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '\\', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '\\', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	sb.state.runConfig.Env = []string{"var1=old", "var2=fromenv"}

 	envCommand := &instructions.EnvCommand{

 		Env: instructions.KeyValuePairs{

@@ -79,7 +79,7 @@ func TestEnvValueWithExistingRunConfigEnv(t *testing.T) {

 func TestMaintainer(t *testing.T) {

 	maintainerEntry := "Some Maintainer <maintainer@example.com>"

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '\\', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '\\', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	cmd := &instructions.MaintainerCommand{Maintainer: maintainerEntry}

 	err := dispatch(sb, cmd)

 	assert.NilError(t, err)

@@ -91,7 +91,7 @@ func TestLabel(t *testing.T) {

 	labelValue := "value"

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '\\', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '\\', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	cmd := &instructions.LabelCommand{

 		Labels: instructions.KeyValuePairs{

 			instructions.KeyValuePair{Key: labelName, Value: labelValue},

@@ -106,7 +106,7 @@ func TestLabel(t *testing.T) {

 func TestFromScratch(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '\\', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '\\', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	cmd := &instructions.Stage{

 		BaseName: "scratch",

 	}

@@ -133,7 +133,7 @@ func TestFromWithArg(t *testing.T) {

 	}

 	b := newBuilderWithMockBackend()

 	b.docker.(*MockBackend).getImageFunc = getImage

-	args := newBuildArgs(make(map[string]*string))

+	args := NewBuildArgs(make(map[string]*string))

 	val := "sometag"

 	metaArg := instructions.ArgCommand{

@@ -165,7 +165,7 @@ func TestFromWithUndefinedArg(t *testing.T) {

 	}

 	b := newBuilderWithMockBackend()

 	b.docker.(*MockBackend).getImageFunc = getImage

-	sb := newDispatchRequest(b, '\\', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '\\', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	b.options.BuildArgs = map[string]*string{"THETAG": &tag}

@@ -182,8 +182,8 @@ func TestFromMultiStageWithNamedStage(t *testing.T) {

 	firstFrom := &instructions.Stage{BaseName: "someimg", Name: "base"}

 	secondFrom := &instructions.Stage{BaseName: "base"}

 	previousResults := newStagesBuildResults()

-	firstSB := newDispatchRequest(b, '\\', nil, newBuildArgs(make(map[string]*string)), previousResults)

-	secondSB := newDispatchRequest(b, '\\', nil, newBuildArgs(make(map[string]*string)), previousResults)

+	firstSB := newDispatchRequest(b, '\\', nil, NewBuildArgs(make(map[string]*string)), previousResults)

+	secondSB := newDispatchRequest(b, '\\', nil, NewBuildArgs(make(map[string]*string)), previousResults)

 	err := initializeStage(firstSB, firstFrom)

 	assert.NilError(t, err)

 	assert.Check(t, firstSB.state.hasFromImage())

@@ -196,7 +196,7 @@ func TestFromMultiStageWithNamedStage(t *testing.T) {

 func TestOnbuild(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '\\', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '\\', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	cmd := &instructions.OnbuildCommand{

 		Expression: "ADD . /app/src",

 	}

@@ -207,7 +207,7 @@ func TestOnbuild(t *testing.T) {

 func TestWorkdir(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	sb.state.baseImage = &mockImage{}

 	workingDir := "/app"

 	if runtime.GOOS == "windows" {

@@ -224,7 +224,7 @@ func TestWorkdir(t *testing.T) {

 func TestCmd(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	sb.state.baseImage = &mockImage{}

 	command := "./executable"

@@ -250,7 +250,7 @@ func TestCmd(t *testing.T) {

 func TestHealthcheckNone(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	cmd := &instructions.HealthCheckCommand{

 		Health: &container.HealthConfig{

 			Test: []string{"NONE"},

@@ -266,7 +266,7 @@ func TestHealthcheckNone(t *testing.T) {

 func TestHealthcheckCmd(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	expectedTest := []string{"CMD-SHELL", "curl -f http://localhost/ || exit 1"}

 	cmd := &instructions.HealthCheckCommand{

 		Health: &container.HealthConfig{

@@ -282,7 +282,7 @@ func TestHealthcheckCmd(t *testing.T) {

 func TestEntrypoint(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	sb.state.baseImage = &mockImage{}

 	entrypointCmd := "/usr/sbin/nginx"

@@ -307,7 +307,7 @@ func TestEntrypoint(t *testing.T) {

 func TestExpose(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	exposedPort := "80"

 	cmd := &instructions.ExposeCommand{

@@ -326,7 +326,7 @@ func TestExpose(t *testing.T) {

 func TestUser(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	cmd := &instructions.UserCommand{

 		User: "test",

@@ -338,7 +338,7 @@ func TestUser(t *testing.T) {

 func TestVolume(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	exposedVolume := "/foo"

@@ -358,7 +358,7 @@ func TestStopSignal(t *testing.T) {

 		return

 	}

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	sb.state.baseImage = &mockImage{}

 	signal := "SIGKILL"

@@ -372,7 +372,7 @@ func TestStopSignal(t *testing.T) {

 func TestArg(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	argName := "foo"

 	argVal := "bar"

@@ -386,7 +386,7 @@ func TestArg(t *testing.T) {

 func TestShell(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', nil, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', nil, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	shellCmd := "powershell"

 	cmd := &instructions.ShellCommand{Shell: strslice.StrSlice{shellCmd}}

@@ -399,7 +399,7 @@ func TestShell(t *testing.T) {

 }

 func TestPrependEnvOnCmd(t *testing.T) {

-	buildArgs := newBuildArgs(nil)

+	buildArgs := NewBuildArgs(nil)

 	buildArgs.AddArg("NO_PROXY", nil)

 	args := []string{"sorted=nope", "args=not", "http_proxy=foo", "NO_PROXY=YA"}

@@ -412,7 +412,7 @@ func TestPrependEnvOnCmd(t *testing.T) {

 func TestRunWithBuildArgs(t *testing.T) {

 	b := newBuilderWithMockBackend()

-	args := newBuildArgs(make(map[string]*string))

+	args := NewBuildArgs(make(map[string]*string))

 	args.argsFromOptions["HTTP_PROXY"] = strPtr("FOO")

 	b.disableCommit = false

 	sb := newDispatchRequest(b, '`', nil, args, newStagesBuildResults())

@@ -111,11 +111,11 @@ type dispatchState struct {

 	imageID         string

 	baseImage       builder.Image

 	stageName       string

-	buildArgs       *buildArgs

+	buildArgs       *BuildArgs

 	operatingSystem string

 }

-func newDispatchState(baseArgs *buildArgs) *dispatchState {

+func newDispatchState(baseArgs *BuildArgs) *dispatchState {

 	args := baseArgs.Clone()

 	args.ResetAllowed()

 	return &dispatchState{runConfig: &container.Config{}, buildArgs: args}

@@ -193,7 +193,7 @@ type dispatchRequest struct {

 	stages  *stagesBuildResults

 }

-func newDispatchRequest(builder *Builder, escapeToken rune, source builder.Source, buildArgs *buildArgs, stages *stagesBuildResults) dispatchRequest {

+func newDispatchRequest(builder *Builder, escapeToken rune, source builder.Source, buildArgs *BuildArgs, stages *stagesBuildResults) dispatchRequest {

 	return dispatchRequest{

 		state:   newDispatchState(buildArgs),

 		shlex:   shell.NewLex(escapeToken),

@@ -137,7 +137,7 @@ func executeTestCase(t *testing.T, testCase dispatchTestCase) {

 	}()

 	b := newBuilderWithMockBackend()

-	sb := newDispatchRequest(b, '`', context, newBuildArgs(make(map[string]*string)), newStagesBuildResults())

+	sb := newDispatchRequest(b, '`', context, NewBuildArgs(make(map[string]*string)), newStagesBuildResults())

 	err = dispatch(sb, testCase.cmd)

 	testutil.ErrorContains(t, err, testCase.expectedError)

 }