Fix executor panic (fix #653)

src/error.rs

@@ -22,6 +22,10 @@ pub enum TopgradeError {
 #[error("A step failed")]
 pub struct StepFailed;
 
+#[derive(Error, Debug)]
+#[error("Dry running")]
+pub struct DryRun();
+
 #[derive(Error, Debug)]
 #[error("{0}")]
 pub struct SkipStep(pub String);

src/executor.rs

@@ -1,5 +1,5 @@
 //! Utilities for command execution
-use crate::error::TopgradeError;
+use crate::error::{DryRun, TopgradeError};
 use crate::utils::{Check, CheckWithCodes};
 use anyhow::Result;
 use log::{debug, trace};
@@ -270,7 +270,7 @@ impl CommandExt for Executor {
     fn check_output(&mut self) -> Result<String> {
         let output = match self.output()? {
             ExecutorOutput::Wet(output) => output,
-            ExecutorOutput::Dry => unreachable!(),
+            ExecutorOutput::Dry => return Err(DryRun().into()),
         };
         let status = output.status;
         if !status.success() {
@@ -283,7 +283,7 @@ impl CommandExt for Executor {
     fn string_output(&mut self) -> Result<String> {
         let output = match self.output()? {
             ExecutorOutput::Wet(output) => output,
-            ExecutorOutput::Dry => unreachable!(),
+            ExecutorOutput::Dry => return Err(DryRun().into()),
         };
         Ok(String::from_utf8(output.stdout)?)
     }

src/runner.rs

@@ -1,5 +1,5 @@
 use crate::ctrlc;
-use crate::error::SkipStep;
+use crate::error::{DryRun, SkipStep};
 use crate::execution_context::ExecutionContext;
 use crate::report::{Report, StepResult};
 use crate::{config::Step, terminal::should_retry};
@@ -39,6 +39,7 @@ impl<'a> Runner<'a> {
                     self.report.push_result(Some((key, StepResult::Success)));
                     break;
                 }
+                Err(e) if e.downcast_ref::<DryRun>().is_some() => break,
                 Err(e) if e.downcast_ref::<SkipStep>().is_some() => {
                     if self.ctx.config().verbose() || self.ctx.config().show_skipped() {
                         self.report.push_result(Some((key, StepResult::Skipped(e.to_string()))));