[cargo-nextest] execute integration tests as subprocesses

Previously, we were executing cargo-nextest in-process due to the fact
that we can't replace binaries on Windows while they're running. To
solve that issue, create a separate crate with a separate
"cargo-nextest-dup" binary that's only used for integration tests, and
is otherwise identical to the cargo-nextest binary.

We're going to need this for upcoming double-spawn work.

Author: sunshowers

Cargo.lock

@@ -2,6 +2,7 @@
 resolver = "2"
 members = [
   "cargo-nextest",
+  "integration-tests",
   "nextest-metadata",
   "nextest-runner",
   "nextest-filtering",

Cargo.toml

@@ -40,11 +40,6 @@ serde_json = "1.0.87"
 thiserror = "1.0.37"
 nextest-workspace-hack = { version = "0.1", path = "../workspace-hack" }
 
-[dev-dependencies]
-cfg-if = "1.0.0"
-tempfile = "3.3.0"
-regex = "1.6.0"
-
 [features]
 default = ["default-no-update", "self-update"]
 # Perform self-updates (enabled by default)

cargo-nextest/Cargo.toml

@@ -21,9 +21,6 @@ mod reuse_build;
 #[cfg(feature = "self-update")]
 mod update;
 
-#[cfg(test)]
-mod tests_integration;
-
 #[doc(hidden)]
 pub use dispatch::*;
 #[doc(hidden)]

cargo-nextest/src/lib.rs

@@ -209,14 +209,6 @@ impl Default for OutputWriter {
 }
 
 impl OutputWriter {
-    #[cfg(test)]
-    pub(crate) fn new_test() -> Self {
-        Self::Test {
-            stdout: Vec::new(),
-            stderr: Vec::new(),
-        }
-    }
-
     pub(crate) fn stdout_writer(&mut self) -> StdoutWriter<'_> {
         match self {
             Self::Normal => StdoutWriter::Normal {
@@ -250,24 +242,6 @@ impl OutputWriter {
             },
         }
     }
-
-    #[cfg(test)]
-    pub(crate) fn stdout(&self) -> Option<&'_ [u8]> {
-        match self {
-            Self::Test { ref stdout, .. } => Some(&stdout[..]),
-            #[cfg(test)]
-            _ => None,
-        }
-    }
-
-    #[cfg(test)]
-    pub(crate) fn stderr(&self) -> Option<&'_ [u8]> {
-        match self {
-            Self::Test { ref stderr, .. } => Some(&stderr[..]),
-            #[cfg(test)]
-            _ => None,
-        }
-    }
 }
 
 pub(crate) enum StdoutWriter<'a> {