fix(helm): Don't discard pre-releases upon index merge

Previously, when attempting to merge a new version into an existing
index.yaml which includes overlapping release and pre-release versions
(such as 0.1.0 and 0.1-dev), the merge would silently discard the
pre-release version from the newly merged index.

Fix this by performing an exact semantic comparison of the versions from
the provided index file.

Signed-off-by: Joe Stringer <joe@cilium.io>

pkg/repo/index.go

@@ -135,8 +135,13 @@ func (i IndexFile) Add(md *chart.Metadata, filename, baseURL, digest string) {
 
 // Has returns true if the index has an entry for a chart with the given name and exact version.
 func (i IndexFile) Has(name, version string) bool {
-	_, err := i.Get(name, version)
-	return err == nil
+	vs := i.Entries[name]
+	for _, v := range vs {
+		if v.Version == version {
+			return true
+		}
+	}
+	return false
 }
 
 // SortEntries sorts the entries by version in descending order.

pkg/repo/index_test.go

@@ -214,6 +214,81 @@ func TestMerge(t *testing.T) {
 
 }
 
+func TestMergePrerelease(t *testing.T) {
+	ind1 := NewIndexFile()
+	ind1.Add(&chart.Metadata{
+		Name:    "dreadnought",
+		Version: "0.2.0",
+	}, "dreadnought-0.2.0.tgz", "http://example.com", "aaaa")
+
+	ind2 := NewIndexFile()
+	ind2.Add(&chart.Metadata{
+		Name:    "dreadnought",
+		Version: "0.1.0",
+	}, "dreadnought-0.1.0.tgz", "http://example.com", "aaaabbbb")
+	ind2.Add(&chart.Metadata{
+		Name:    "dreadnought",
+		Version: "0.1-dev",
+	}, "dreadnought-0.1-dev.tgz", "http://example.com", "ccccbbbb")
+
+	ind1.Merge(ind2)
+
+	if len(ind1.Entries) != 1 {
+		t.Errorf("Expected 1 entries, got %d", len(ind1.Entries))
+	}
+	vs := ind1.Entries["dreadnought"]
+	if len(vs) != 3 {
+		t.Errorf("Expected 3 versions, got %d", len(vs))
+		for i := 0; i < len(vs); i++ {
+			t.Errorf("* %+v", ind1.Entries["dreadnought"][i].Metadata.Version)
+		}
+	}
+	v := vs[0]
+	if v.Version != "0.2.0" {
+		t.Errorf("Expected %q version to be 0.2.0, got %s", v.Name, v.Version)
+	}
+
+}
+
+func TestMergeSameVersion(t *testing.T) {
+	ind1 := NewIndexFile()
+	ind1.Add(&chart.Metadata{
+		Name:    "dreadnought",
+		Version: "0.2.0",
+	}, "dreadnought-0.2.0.tgz", "http://example.com", "aaaa")
+
+	ind2 := NewIndexFile()
+	ind2.Add(&chart.Metadata{
+		Name:    "dreadnought",
+		Version: "0.2.0",
+	}, "dreadnought-0.2.0.tgz", "http://example.com", "aaaabbbb")
+	ind2.Add(&chart.Metadata{
+		Name:    "dreadnought",
+		Version: "0.1-dev",
+	}, "dreadnought-0.1-dev.tgz", "http://example.com", "ccccbbbb")
+
+	ind1.Merge(ind2)
+
+	if len(ind1.Entries) != 1 {
+		t.Errorf("Expected 1 entries, got %d", len(ind1.Entries))
+	}
+	vs := ind1.Entries["dreadnought"]
+	if len(vs) != 2 {
+		t.Errorf("Expected 2 versions, got %d", len(vs))
+		for i := 0; i < len(vs); i++ {
+			t.Errorf("* %+v", ind1.Entries["dreadnought"][i].Metadata.Version)
+		}
+	}
+	v := vs[0]
+	if v.Version != "0.2.0" {
+		t.Errorf("Expected %q version to be 0.2.0, got %s", v.Name, v.Version)
+	}
+	expectedDigest := "aaaa"
+	if v.Digest != expectedDigest {
+		t.Errorf("Expected merged %q digest to be %q, got %s", v.Name, expectedDigest, v.Digest)
+	}
+}
+
 func TestDownloadIndexFile(t *testing.T) {
 	t.Run("should  download index file", func(t *testing.T) {
 		srv, err := startLocalServerForTests(nil)