digest: remove stuttering ParseDigest function

Signed-off-by: Stephen J Day <stephen.day@docker.com>

digest.go

@@ -63,12 +63,16 @@ var (
 
 // ParseDigest parses s and returns the validated digest object. An error will
 // be returned if the format is invalid.
-func ParseDigest(s string) (Digest, error) {
+func Parse(s string) (Digest, error) {
 	d := Digest(s)
-
 	return d, d.Validate()
 }
 
+// ParseDigest is deprecated. Use Parse.
+func ParseDigest(s string) (Digest, error) {
+	return Parse(s)
+}
+
 // FromReader returns the most valid digest for the underlying content using
 // the canonical digest algorithm.
 func FromReader(rd io.Reader) (Digest, error) {

digest_test.go

@@ -51,7 +51,7 @@ func TestParseDigest(t *testing.T) {
 			err:   ErrDigestUnsupported,
 		},
 	} {
-		digest, err := ParseDigest(testcase.input)
+		digest, err := Parse(testcase.input)
 		if err != testcase.err {
 			t.Fatalf("error differed from expected while parsing %q: %v != %v", testcase.input, err, testcase.err)
 		}
@@ -69,7 +69,7 @@ func TestParseDigest(t *testing.T) {
 		}
 
 		// Parse string return value and check equality
-		newParsed, err := ParseDigest(digest.String())
+		newParsed, err := Parse(digest.String())
 
 		if err != nil {
 			t.Fatalf("unexpected error parsing input %q: %v", testcase.input, err)