initialize: add tests for ParseMetadata

initialize/meta_data.go

@@ -4,7 +4,10 @@ import "encoding/json"
 
 // ParseMetaData parses a JSON blob in the OpenStack metadata service format, and
 // converts it to a partially hydrated CloudConfig
-func ParseMetaData(contents string) (cfg *CloudConfig, err error) {
+func ParseMetaData(contents string) (*CloudConfig, error) {
+	if len(contents) == 0 {
+		return nil, nil
+	}
 	var metadata struct {
 		SSHAuthorizedKeyMap map[string]string `json:"public_keys"`
 		Hostname            string            `json:"hostname"`
@@ -12,17 +15,20 @@ func ParseMetaData(contents string) (cfg *CloudConfig, err error) {
 			ContentPath string `json:"content_path"`
 		} `json:"network_config"`
 	}
-	if err = json.Unmarshal([]byte(contents), &metadata); err != nil {
-		return
+	if err := json.Unmarshal([]byte(contents), &metadata); err != nil {
+		return nil, err
 	}
 
-	cfg.SSHAuthorizedKeys = make([]string, 0, len(metadata.SSHAuthorizedKeyMap))
-	for _, key := range metadata.SSHAuthorizedKeyMap {
-		cfg.SSHAuthorizedKeys = append(cfg.SSHAuthorizedKeys, key)
+	var cfg CloudConfig
+	if len(metadata.SSHAuthorizedKeyMap) > 0 {
+		cfg.SSHAuthorizedKeys = make([]string, 0, len(metadata.SSHAuthorizedKeyMap))
+		for _, key := range metadata.SSHAuthorizedKeyMap {
+			cfg.SSHAuthorizedKeys = append(cfg.SSHAuthorizedKeys, key)
+		}
 	}
 	cfg.Hostname = metadata.Hostname
 	cfg.NetworkConfigPath = metadata.NetworkConfig.ContentPath
-	return
+	return &cfg, nil
 }
 
 // ExtractIPsFromMetaData parses a JSON blob in the OpenStack metadata service format,

initialize/meta_data_test.go

@@ -3,6 +3,39 @@ package initialize
 import "reflect"
 import "testing"
 
+func TestParseMetadata(t *testing.T) {
+	for i, tt := range []struct {
+		in   string
+		want *CloudConfig
+		err  bool
+	}{
+		{"", nil, false},
+		{`garbage, invalid json`, nil, true},
+		{`{"foo": "bar"}`, &CloudConfig{}, false},
+		{`{"network_config": {"content_path": "asdf"}}`, &CloudConfig{NetworkConfigPath: "asdf"}, false},
+		{`{"hostname": "turkleton"}`, &CloudConfig{Hostname: "turkleton"}, false},
+		{`{"public_keys": {"jack": "jill", "bob": "alice"}}`, &CloudConfig{SSHAuthorizedKeys: []string{"jill", "alice"}}, false},
+		{`{"unknown": "thing", "hostname": "my_host", "public_keys": {"do": "re", "mi": "fa"}, "network_config": {"content_path": "/root", "blah": "zzz"}}`, &CloudConfig{SSHAuthorizedKeys: []string{"re", "fa"}, Hostname: "my_host", NetworkConfigPath: "/root"}, false},
+	} {
+		got, err := ParseMetaData(tt.in)
+		if tt.err != (err != nil) {
+			t.Errorf("case #%d: bad error state: got %t, want %t (err=%v)", i, (err != nil), tt.err, err)
+		}
+		if got == nil {
+			if tt.want != nil {
+				t.Errorf("case #%d: unexpected nil output", i)
+			}
+		} else if tt.want == nil {
+			t.Errorf("case #%d: unexpected non-nil output", i)
+		} else {
+			if !reflect.DeepEqual(*got, *tt.want) {
+				t.Errorf("case #%d: bad output:\ngot\n%v\nwant\n%v", i, *got, *tt.want)
+			}
+		}
+	}
+
+}
+
 func TestExtractIPsFromMetadata(t *testing.T) {
 	for i, tt := range []struct {
 		in  []byte