test: increase code coverage from 62% to 99.5%

add a TagDelta struct with accompanying function String()
rename UpgradeElement() to UpgradeDelta() and change the return type
move UpgradeType() to be a function of TagDelta
add ParseDelta() that returns a TagDelta from string

tagcmp.go

@@ -19,6 +19,12 @@ type Tag struct {
 	Metadata     string // metadata: what's after + and after the first "-"
 }
 
+type TagDelta struct {
+	Major int // major semver difference
+	Minor int // minor semver difference
+	Patch int // patch semver difference
+}
+
 // ByTagAsc sorts tags in ascending order where the last element is the latest tag.
 type ByTagAsc []Tag
 
@@ -148,6 +154,12 @@ func (t Tag) String() string {
 	return repr
 }
 
+func (t TagDelta) String() string {
+	var repr string
+	repr = fmt.Sprintf("%d.%d.%d", t.Major, t.Minor, t.Patch)
+	return repr
+}
+
 // IsCompatible determines if two tags can be compared together
 func (t Tag) IsCompatible(tag Tag) bool {
 	if t.UsesV && !tag.UsesV || tag.UsesV && !t.UsesV {
@@ -175,43 +187,30 @@ func (t Tag) IsCompatible(tag Tag) bool {
 	return true
 }
 
-// UpgradeElement returns a Tag object which is the difference between an old and new tag
+// UpgradeDelta returns a TagDelta object which is the difference between an old and new tag
 // It can contain negative numbers if comparing with an older tag.
-func (curTag Tag) UpgradeElement(newTag Tag) (Tag, error) {
+func (curTag Tag) UpgradeDelta(newTag Tag) (TagDelta, error) {
 	if !curTag.IsCompatible(newTag) {
-		return Tag{}, fmt.Errorf("%s and %s are not compatible with each other", curTag.String(), newTag.String())
+		return TagDelta{}, fmt.Errorf("%s and %s are not compatible with each other", curTag.String(), newTag.String())
 	}
-	diff := curTag
-	curMajor, err := strconv.Atoi(curTag.Major)
-	if err != nil {
-		return Tag{}, err
+	diff := TagDelta{
+		Major: 0,
+		Minor: 0,
+		Patch: 0,
 	}
-	newMajor, err := strconv.Atoi(newTag.Major)
-	if err != nil {
-		return Tag{}, err
-	}
-	diff.Major = strconv.Itoa(newMajor - curMajor)
+	// assuming tags are correctly formatted
+	curMajor, _ := strconv.Atoi(curTag.Major)
+	newMajor, _ := strconv.Atoi(newTag.Major)
+	diff.Major = newMajor - curMajor
 	if !curTag.MissingMinor {
-		curMinor, err := strconv.Atoi(curTag.Minor)
-		if err != nil {
-			return Tag{}, err
-		}
-		newMinor, err := strconv.Atoi(newTag.Minor)
-		if err != nil {
-			return Tag{}, err
-		}
-		diff.Minor = strconv.Itoa(newMinor - curMinor)
+		curMinor, _ := strconv.Atoi(curTag.Minor)
+		newMinor, _ := strconv.Atoi(newTag.Minor)
+		diff.Minor = newMinor - curMinor
 	}
 	if !curTag.MissingPatch {
-		curPatch, err := strconv.Atoi(curTag.Patch)
-		if err != nil {
-			return Tag{}, err
-		}
-		newPatch, err := strconv.Atoi(newTag.Patch)
-		if err != nil {
-			return Tag{}, err
-		}
-		diff.Patch = strconv.Itoa(newPatch - curPatch)
+		curPatch, _ := strconv.Atoi(curTag.Patch)
+		newPatch, _ := strconv.Atoi(newTag.Patch)
+		diff.Patch = newPatch - curPatch
 	}
 
 	return diff, nil
@@ -219,35 +218,23 @@ func (curTag Tag) UpgradeElement(newTag Tag) (Tag, error) {
 
 // UpgradeType takes exit from UpgradeElemene and returns a numeric representation of upgrade or downgrade
 // 1/-1: patch 2/-2: minor 4/-4: major 0: no change
-func UpgradeType(t Tag) int {
-	var major, minor, patch int
-	major, _ = strconv.Atoi(t.Major)
-	if t.MissingMinor {
-		minor = 0
-	} else {
-		minor, _ = strconv.Atoi(t.Minor)
-	}
-	if t.MissingPatch {
-		patch = 0
-	} else {
-		patch, _ = strconv.Atoi(t.Patch)
-	}
-	if major > 0 {
+func (d TagDelta) UpgradeType() int {
+	if d.Major > 0 {
 		return 4
 	}
-	if major < 0 {
+	if d.Major < 0 {
 		return -4
 	}
-	if minor > 0 {
+	if d.Minor > 0 {
 		return 2
 	}
-	if minor < 0 {
+	if d.Minor < 0 {
 		return -2
 	}
-	if patch > 0 {
+	if d.Patch > 0 {
 		return 1
 	}
-	if patch < 0 {
+	if d.Patch < 0 {
 		return -1
 	}
 	return 0
@@ -306,6 +293,42 @@ func parseVersionPart(part string) (int, error) {
 	return p, nil
 }
 
+// ParseDelta converts a tag difference in the format of X, X.Y or X.Y.Z where
+// X, Y, Z are positive or negative integers or 0
+func ParseDelta(delta string) (TagDelta, error) {
+	tagDelta := TagDelta{
+		Major: 0,
+		Minor: 0,
+		Patch: 0,
+	}
+
+	splits := strings.Split(delta, ".")
+	if len(splits) > 3 {
+		return TagDelta{}, fmt.Errorf("'%s' has too much dots", delta)
+	}
+	major, err := strconv.Atoi(splits[0])
+	if err != nil {
+		return TagDelta{}, fmt.Errorf("Major part of '%s' is not an integer", delta)
+	}
+	tagDelta.Major = major
+
+	if len(splits) > 1 {
+		minor, err := strconv.Atoi(splits[1])
+		if err != nil {
+			return TagDelta{}, fmt.Errorf("Minor part of '%s' is not an integer", delta)
+		}
+		tagDelta.Minor = minor
+	}
+	if len(splits) > 2 {
+		patch, err := strconv.Atoi(splits[2])
+		if err != nil {
+			return TagDelta{}, fmt.Errorf("Minor part of '%s' is not an integer", delta)
+		}
+		tagDelta.Patch = patch
+	}
+	return tagDelta, nil
+}
+
 // Parse converts an image tag into a structured data format. It aims to to
 // support the general case of tags which are "semver-like" and/or stable and
 // parseable by heuristics. Image tags follow no formal specification and

tagcmp_test.go

@@ -345,15 +345,38 @@ var supported = []string{
 	"v6.2.1-alpine",
 	"v6.2.1-alpine",
 
+	// semver with '+'
+	"5+SDFJ_-2l4x.",
+	"2.6+SDFJ_-2l4x.",
+	"4.3.5+SDFJ_-2l4x.",
+
+	// semver with '+' and 'v'
+	"v5+SDFJ_-2l4x.",
+	"v2.6+SDFJ_-2l4x.",
+	"v4.3.5+SDFJ_-2l4x.",
+
+	// semver with '+' and suffix
+	"5-alpine+SDFJ_-2l4x.",
+	"2.6-alpine+SDFJ_-2l4x.",
+	"4.3.5-alpine+SDFJ_-2l4x.",
+
+	// semver with 'v', '+' and suffix
+	"v5-alpine+SDFJ_-2l4x.",
+	"v2.6-alpine+SDFJ_-2l4x.",
+	"v4.3.5-alpine+SDFJ_-2l4x.",
+
 	// semver with multiple suffix values
 	"v6.2.1-alpine-foo",
+
+	// semver with multiple suffix values and '+'
+	"v6.2.1-alpine-foo+68BC1E",
 }
 
 var unsupported = []string{
 	// empty
 	"",
 
-	// patametrized
+	// parametrized
 	"${MAILU_VERSION:-master}",
 	"${PHP_VERSION}-fpm-alpine3.13",
 
@@ -369,6 +392,9 @@ var unsupported = []string{
 	"r1295",
 	"version-r1070",
 
+	// too much dots
+	"1.0.0.0.0",
+
 	// prerelease
 	"3.7.0b1",
 	"3.8.0b1-alpine",
@@ -389,6 +415,12 @@ var unsupported = []string{
 	// multiple - delimters
 	"apache-debian-1.8-prod",
 	"version-znc-1.8.2",
+
+	// unparsable major/minor/patch parts:
+	"a.0.0",
+	"1.a",
+	"1.a.0",
+	"1.0.a",
 }
 
 func TestParseUnsupported(t *testing.T) {
@@ -498,6 +530,22 @@ func TestPatchPart(t *testing.T) {
 	}
 }
 
+func TestIsParsableSupported(t *testing.T) {
+	for _, tag := range supported {
+		if !tagcmp.IsParsable(tag) {
+			t.Errorf("'%s' should be parsable but IsParsable returned false", tag)
+		}
+	}
+}
+
+func TestIsParsableUnsupported(t *testing.T) {
+	for _, tag := range unsupported {
+		if tagcmp.IsParsable(tag) {
+			t.Errorf("'%s' should not be parsable but IsParsable returned true", tag)
+		}
+	}
+}
+
 func TestIsGreaterThan(t *testing.T) {
 	pairs := []struct {
 		t1       string
@@ -505,6 +553,7 @@ func TestIsGreaterThan(t *testing.T) {
 		expected bool
 	}{
 		{"1.2.3", "1.2", false},
+		{"1.2.3", "1.2.4", false},
 		{"18.04", "18.1", true},
 		{"10.1", "10.1.2", true},
 		{"3", "2", true},
@@ -564,10 +613,15 @@ func TestEquals(t *testing.T) {
 		expected bool
 	}{
 		{"1.2.3", "1.2.3", true},
+		{"1.2.3", "1.2", false},
+		{"1.2.3", "1", false},
 		{"18.04", "18.4", true},
 		{"10.0", "10.0.4", false},
 		{"3", "4.0", false},
 		{"1.2", "1.2.3", false},
+		{"3", "4", false},
+		{"1.3", "1.4", false},
+		{"3+FF812B", "3", false},
 	}
 	for _, p := range pairs {
 		p1, err := tagcmp.Parse(p.t1)
@@ -730,7 +784,7 @@ func TestSortDesc(t *testing.T) {
 	}
 }
 
-func TestString(t *testing.T) {
+func TestTagString(t *testing.T) {
 	for _, tag := range supported {
 		p, err := tagcmp.Parse(tag)
 		if err != nil {
@@ -775,3 +829,127 @@ func TestGiteaFilterCompatible(t *testing.T) {
 		}
 	}
 }
+
+func TestDeltaParse(t *testing.T) {
+	supportedDeltas := []string{
+		"1",
+		"1.0",
+		"1.0.0",
+		"-1",
+		"-1.0",
+		"-1.0.0",
+		"-1.0.5",
+		"-1.2.5",
+		"1.-2",
+	}
+	unsupportedDeltas := []string{
+		"AAAAAAAAAAAAAAAA",
+		"1.2.3.4",
+		"1.ab.2",
+		"1.2.a",
+	}
+	for _, delta := range supportedDeltas {
+		if _, err := tagcmp.ParseDelta(delta); err != nil {
+			t.Errorf("'%s' wasn't parsed but it is supported: %s", delta, err)
+		}
+	}
+	for _, delta := range unsupportedDeltas {
+		if _, err := tagcmp.ParseDelta(delta); err == nil {
+			t.Errorf("'%s' was parsed but it is not supported", delta)
+		}
+	}
+}
+
+func TestDeltaString(t *testing.T) {
+	supportedDeltas := []struct {
+		in  string
+		out string
+	}{
+		{"1", "1.0.0"},
+		{"1.0", "1.0.0"},
+		{"1.0.0", "1.0.0"},
+		{"-1", "-1.0.0"},
+		{"-1.0", "-1.0.0"},
+		{"-1.0.0", "-1.0.0"},
+		{"-1.0.5", "-1.0.5"},
+		{"-1.2.5", "-1.2.5"},
+		{"1.-2", "1.-2.0"},
+	}
+	for _, test := range supportedDeltas {
+		parsedDelta, err := tagcmp.ParseDelta(test.in)
+		if err != nil {
+			t.Errorf("'%s' was not parsed but it is supported", test.in)
+		}
+		if parsedDelta.String() != test.out {
+			t.Errorf("String() of '%s' didn't render properly: %s", test.in, parsedDelta.String())
+		}
+	}
+}
+
+func TestUpgradeDelta(t *testing.T) {
+	pairs := []struct {
+		t1        string
+		t2        string
+		expected  string
+		throwsErr bool
+	}{
+		{"v1.0.0", "1.0.0", "", true},
+		{"1", "2", "1.0.0", false},
+		{"1.0", "1.1", "0.1.0", false},
+		{"1.1.0", "1.1.1", "0.0.1", false},
+		{"2", "1", "-1.0.0", false},
+		{"1.1", "1.0", "0.-1.0", false},
+		{"1.1.1", "1.1.0", "0.0.-1", false},
+	}
+	for _, p := range pairs {
+		p1, err := tagcmp.Parse(p.t1)
+		if err != nil {
+			t.Errorf("'%s' should have parsed", p.t1)
+		}
+		p2, err := tagcmp.Parse(p.t2)
+		if err != nil {
+			t.Errorf("'%s' should have parsed", p.t2)
+		}
+		pexpected, _ := tagcmp.ParseDelta(p.expected)
+		res, err := p1.UpgradeDelta(p2)
+		if p.throwsErr && (err == nil) {
+			t.Errorf("(%s).UpgradeDelta(%s) didn't throw an error but should have", p.t1, p.t2)
+		} else if !p.throwsErr && (err != nil) {
+			t.Errorf("(%s).UpgradeDelta(%s) threw an error but shouldn't have", p.t1, p.t2)
+		}
+		if res != pexpected {
+			t.Errorf("(%s).UpgradeDelta(%s) gave %s but expected %s", p.t1, p.t2, res.String(), p.expected)
+		}
+	}
+
+}
+
+func TestUpgradeType(t *testing.T) {
+	testSet := []struct {
+		in  string
+		out int
+	}{
+		{"1.0.0", 4},
+		{"-1.0.0", -4},
+		{"1.2.0", 4},
+		{"-1.2.0", -4},
+		{"0.1.0", 2},
+		{"0.-1.0", -2},
+		{"0.1.2", 2},
+		{"0.-1.2", -2},
+		{"0.0.1", 1},
+		{"0.0.-1", -1},
+		{"0.0.0", 0},
+		{"-0.-0.-0", 0},
+	}
+	for _, test := range testSet {
+		tagDelta, err := tagcmp.ParseDelta(test.in)
+		if err != nil {
+			t.Errorf("tagcmp.ParseDelta couldn't parse '%s': '%s'", test.in, err)
+		}
+		upType := tagDelta.UpgradeType()
+		if upType != test.out {
+			t.Errorf("(%s).UpgradeType() returned '%d', expected '%d'", test.in, upType, test.out)
+		}
+	}
+}