Change upgradeable logic based on feedback

Signed-off-by: Richard Gee <richard@technologee.co.uk>

cmd/chart/upgrade.go

@@ -207,6 +207,6 @@ func tagIsUpgradeable(currentTag, latestTag string) bool {
 	currentSemVer, _ := semver.NewVersion(currentTag)
 	latestSemVer, _ := semver.NewVersion(latestTag)
 
-	return latestTag != currentTag && len(latestSemVer.Prerelease()) == 0 && len(currentSemVer.Prerelease()) == 0
+	return latestSemVer.Compare(currentSemVer) == 1 && latestSemVer.Prerelease() == currentSemVer.Prerelease()
 
 }

cmd/chart/upgrade_test.go

@@ -53,6 +53,42 @@ func Test_tagIsUpgradable(t *testing.T) {
 			latest:   "1.0.0",
 			expected: false,
 		},
+		{
+			title:    "both are rootless different version'",
+			current:  "1.0.0-rootless",
+			latest:   "1.0.1-rootless",
+			expected: true,
+		},
+		{
+			title:    "both are rootless same version'",
+			current:  "1.0.0-rootless",
+			latest:   "1.0.0-rootless",
+			expected: false,
+		},
+		{
+			title:    "both are rc same version'",
+			current:  "1.0.0-rc",
+			latest:   "1.0.0-rc",
+			expected: false,
+		},
+		{
+			title:    "both are rc different version'",
+			current:  "1.0.0-rc",
+			latest:   "1.0.1-rc",
+			expected: true,
+		},
+		{
+			title:    "both are rc with suffix & same version'",
+			current:  "1.0.0-rc1",
+			latest:   "1.0.0-rc2",
+			expected: false,
+		},
+		{
+			title:    "both are rc with suffix & different version'",
+			current:  "1.0.0-rc1",
+			latest:   "1.0.1-rc2",
+			expected: false,
+		},
 	}
 
 	for _, tc := range tests {