radicle-cli-test: Prepare testing with `jj`

Most of this is taken from Jujutsu's own testing setup, see:
98d884827e/cli/tests/common/test_environment.rs (L106-L150)

Not all features are preserved, but this is good enough.

crates/radicle-cli-test/src/lib.rs

@@ -124,6 +124,7 @@ impl<'a> TestRunner<'a> {
 
         if let Some(ref h) = test.home {
             if let Some(home) = self.homes.get(h) {
+                env.insert("USER".to_owned(), h.to_owned());
                 return TestRun {
                     home: home.clone(),
                     env,
@@ -420,7 +421,7 @@ impl TestFormula {
             let mut run = runner.run(test);
 
             // For each command.
-            for assertion in &test.assertions {
+            for (i, assertion) in test.assertions.iter().enumerate() {
                 // Expand environment variables.
                 let mut args = assertion.args.clone();
                 for arg in &mut args {
@@ -464,6 +465,16 @@ impl TestFormula {
                     fs::create_dir_all(run.path())?;
                 }
 
+                let jj_envs = if assertion.command == "jj" {
+                    vec![
+                        ("JJ_RANDOMNESS_SEED", i.to_string()),
+                        ("JJ_TIMESTAMP", "2001-02-03T04:05:06+07:00".to_string()),
+                        ("JJ_OP_TIMESTAMP", "2001-02-03T04:05:06+07:00".to_string()),
+                    ]
+                } else {
+                    vec![]
+                };
+
                 let bins = self
                     .bins
                     .iter()
@@ -474,6 +485,7 @@ impl TestFormula {
                     .env_clear()
                     .env("PATH", &bins)
                     .env("RUST_BACKTRACE", "1")
+                    .envs(jj_envs)
                     .envs(run.envs())
                     .current_dir(run.path())
                     .args(args)

crates/radicle-cli/tests/commands.rs

@@ -37,14 +37,23 @@ pub(crate) fn test<'a>(
     envs: impl IntoIterator<Item = (&'a str, &'a str)>,
 ) -> Result<(), Box<dyn std::error::Error>> {
     let tmp = tempfile::tempdir().unwrap();
-    let home = if let Some(home) = home {
-        home.path().to_path_buf()
+
+    let (unix_home, rad_home) = if let Some(home) = home {
+        let unix_home = home.path().to_path_buf();
+        let unix_home = unix_home.parent().unwrap().to_path_buf();
+        (unix_home, home.path().to_path_buf())
     } else {
-        tmp.path().to_path_buf()
+        let mut rad_home = tmp.path().to_path_buf();
+        rad_home.push(".radicle");
+        (tmp.path().to_path_buf(), rad_home)
     };
 
     formula(cwd.as_ref(), test)?
-        .env("RAD_HOME", home.to_string_lossy())
+        .env("RAD_HOME", rad_home.to_string_lossy())
+        .env(
+            "JJ_CONFIG",
+            unix_home.join(".jjconfig.toml").to_string_lossy(),
+        )
         .envs(envs)
         .run()?;
 

crates/radicle-cli/tests/util/environment.rs

@@ -246,6 +246,17 @@ impl Environment {
             "RAD_HOME",
             subject.home().path().to_path_buf().to_string_lossy(),
         )
+        .env(
+            "JJ_CONFIG",
+            subject
+                .home()
+                .path()
+                .parent()
+                .unwrap()
+                .to_path_buf()
+                .join(".jjconfig.toml")
+                .to_string_lossy(),
+        )
         .run()?;
 
         Ok(())

crates/radicle-cli/tests/util/formula.rs

@@ -20,6 +20,11 @@ pub(crate) fn formula(
         .env("GIT_COMMITTER_DATE", "1671125284")
         .env("GIT_COMMITTER_EMAIL", "radicle@localhost")
         .env("GIT_COMMITTER_NAME", "radicle")
+        .env("JJ_USER", "Test User")
+        .env("JJ_EMAIL", "test.user@example.com")
+        .env("JJ_OP_HOSTNAME", "host.example.com")
+        .env("JJ_OP_USERNAME", "test-username")
+        .env("JJ_TZ_OFFSET_MINS", "660")
         .env("EDITOR", "true")
         .env("TZ", "UTC")
         .env("LANG", "C")