fix(json): emit an empty list rather than null when there is nothing to list (#1389)

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 ### Bug Fixes:
 
+- fix(json): `secret-store list --json` emits `[]` rather than `null` on an account with no secret stores
+
 ### Enhancements:
 
 ### Dependencies:

pkg/commands/secretstore/list.go

@@ -45,7 +45,10 @@ func (c *ListCommand) Exec(in io.Reader, out io.Writer) error {
 		return fsterr.ErrInvalidVerboseJSONCombo
 	}
 
-	var data []fastly.SecretStore
+	// Initialised rather than declared nil so that an account with no secret
+	// stores encodes as `[]` instead of `null`: encoding/json writes a nil
+	// slice as null, and `--json` output should be a list either way.
+	data := make([]fastly.SecretStore, 0)
 
 	for {
 		o, err := c.Globals.APIClient.ListSecretStores(context.TODO(), &c.Input)

pkg/commands/secretstore/secretstore_test.go

@@ -341,6 +341,30 @@ func TestListStoresCommand(t *testing.T) {
 			wantAPIInvoked: true,
 			wantOutput:     fstfmt.EncodeJSON([]fastly.SecretStore{stores.Data[0]}),
 		},
+		// An account with no secret stores used to print `null` here while
+		// `config-store list --json` printed `[]` for the same situation.
+		{
+			args: "list --json",
+			api: mock.API{
+				ListSecretStoresFn: func(_ context.Context, _ *fastly.ListSecretStoresInput) (*fastly.SecretStores, error) {
+					return &fastly.SecretStores{Data: []fastly.SecretStore{}}, nil
+				},
+			},
+			wantAPIInvoked: true,
+			wantOutput:     "[]\n",
+		},
+		// The same, reached by the other route: the API returned no response
+		// body at all, so nothing was ever appended.
+		{
+			args: "list --json",
+			api: mock.API{
+				ListSecretStoresFn: func(_ context.Context, _ *fastly.ListSecretStoresInput) (*fastly.SecretStores, error) {
+					return nil, nil
+				},
+			},
+			wantAPIInvoked: true,
+			wantOutput:     "[]\n",
+		},
 	}
 
 	for _, testcase := range scenarios {