Rename Delete to Uninstall [#4]

Helm3 renamed its delete command to uninstall. We should still accept
helm_command=delete for drone-helm compatibility, but the internals
should use Helm's preferred name.

internal/run/uninstall.go

@@ -0,0 +1,51 @@
+package run
+
+import (
+	"fmt"
+)
+
+// Uninstall is an execution step that calls `helm uninstall` when executed.
+type Uninstall struct {
+	Release string
+	DryRun  bool
+	cmd     cmd
+}
+
+// Execute executes the `helm uninstall` command.
+func (u *Uninstall) Execute(_ Config) error {
+	return u.cmd.Run()
+}
+
+// Prepare gets the Uninstall ready to execute.
+func (u *Uninstall) Prepare(cfg Config) error {
+	if u.Release == "" {
+		return fmt.Errorf("release is required")
+	}
+
+	args := []string{"--kubeconfig", cfg.KubeConfig}
+
+	if cfg.Namespace != "" {
+		args = append(args, "--namespace", cfg.Namespace)
+	}
+	if cfg.Debug {
+		args = append(args, "--debug")
+	}
+
+	args = append(args, "uninstall")
+
+	if u.DryRun {
+		args = append(args, "--dry-run")
+	}
+
+	args = append(args, u.Release)
+
+	u.cmd = command(helmBin, args...)
+	u.cmd.Stdout(cfg.Stdout)
+	u.cmd.Stderr(cfg.Stderr)
+
+	if cfg.Debug {
+		fmt.Fprintf(cfg.Stderr, "Generated command: '%s'\n", u.cmd.String())
+	}
+
+	return nil
+}