Move most of the root package into a subcrate. (#1445)

This improves incremental build time when working on what was previously
the root package. For example, previously all plugins would be rebuilt
with a change to `src/commands/classified/external.rs`, but now only
`nu-cli` will have to be rebuilt (and anything that depends on it).

crates/nu-cli/tests/commands/rm.rs

@@ -0,0 +1,161 @@
+use nu_test_support::fs::{files_exist_at, Stub::EmptyFile};
+use nu_test_support::playground::Playground;
+use nu_test_support::{nu, nu_error};
+
+#[test]
+fn removes_a_file() {
+    Playground::setup("rm_test_1", |dirs, sandbox| {
+        sandbox.with_files(vec![EmptyFile("i_will_be_deleted.txt")]);
+
+        nu!(
+            cwd: dirs.root(),
+            "rm rm_test_1/i_will_be_deleted.txt"
+        );
+
+        let path = dirs.test().join("i_will_be_deleted.txt");
+
+        assert!(!path.exists());
+    })
+}
+
+#[test]
+fn removes_files_with_wildcard() {
+    Playground::setup("rm_test_2", |dirs, sandbox| {
+        sandbox
+            .within("src")
+            .with_files(vec![
+                EmptyFile("cli.rs"),
+                EmptyFile("lib.rs"),
+                EmptyFile("prelude.rs"),
+            ])
+            .within("src/parser")
+            .with_files(vec![EmptyFile("parse.rs"), EmptyFile("parser.rs")])
+            .within("src/parser/parse")
+            .with_files(vec![EmptyFile("token_tree.rs")])
+            .within("src/parser/hir")
+            .with_files(vec![
+                EmptyFile("baseline_parse.rs"),
+                EmptyFile("baseline_parse_tokens.rs"),
+            ]);
+
+        nu!(
+            cwd: dirs.test(),
+            r#"rm "src/*/*/*.rs""#
+        );
+
+        assert!(!files_exist_at(
+            vec![
+                "src/parser/parse/token_tree.rs",
+                "src/parser/hir/baseline_parse.rs",
+                "src/parser/hir/baseline_parse_tokens.rs"
+            ],
+            dirs.test()
+        ));
+
+        assert_eq!(
+            Playground::glob_vec(&format!("{}/src/*/*/*.rs", dirs.test().display())),
+            Vec::<std::path::PathBuf>::new()
+        );
+    })
+}
+
+#[test]
+fn removes_deeply_nested_directories_with_wildcard_and_recursive_flag() {
+    Playground::setup("rm_test_3", |dirs, sandbox| {
+        sandbox
+            .within("src")
+            .with_files(vec![
+                EmptyFile("cli.rs"),
+                EmptyFile("lib.rs"),
+                EmptyFile("prelude.rs"),
+            ])
+            .within("src/parser")
+            .with_files(vec![EmptyFile("parse.rs"), EmptyFile("parser.rs")])
+            .within("src/parser/parse")
+            .with_files(vec![EmptyFile("token_tree.rs")])
+            .within("src/parser/hir")
+            .with_files(vec![
+                EmptyFile("baseline_parse.rs"),
+                EmptyFile("baseline_parse_tokens.rs"),
+            ]);
+
+        nu!(
+            cwd: dirs.test(),
+            "rm -r src/*"
+        );
+
+        assert!(!files_exist_at(
+            vec!["src/parser/parse", "src/parser/hir"],
+            dirs.test()
+        ));
+    })
+}
+
+#[test]
+fn removes_directory_contents_without_recursive_flag_if_empty() {
+    Playground::setup("rm_test_4", |dirs, _| {
+        nu!(
+            cwd: dirs.root(),
+            "rm rm_test_4"
+        );
+
+        assert!(!dirs.test().exists());
+    })
+}
+
+#[test]
+fn removes_directory_contents_with_recursive_flag() {
+    Playground::setup("rm_test_5", |dirs, sandbox| {
+        sandbox.with_files(vec![
+            EmptyFile("yehuda.txt"),
+            EmptyFile("jonathan.txt"),
+            EmptyFile("andres.txt"),
+        ]);
+
+        nu!(
+            cwd: dirs.root(),
+            "rm rm_test_5 --recursive"
+        );
+
+        assert!(!dirs.test().exists());
+    })
+}
+
+#[test]
+fn errors_if_attempting_to_delete_a_directory_with_content_without_recursive_flag() {
+    Playground::setup("rm_test_6", |dirs, sandbox| {
+        sandbox.with_files(vec![EmptyFile("some_empty_file.txt")]);
+
+        let actual = nu_error!(
+            cwd: dirs.root(),
+            "rm rm_test_6"
+        );
+
+        assert!(dirs.test().exists());
+        assert!(actual.contains("cannot remove non-empty directory"));
+    })
+}
+
+#[test]
+fn errors_if_attempting_to_delete_single_dot_as_argument() {
+    Playground::setup("rm_test_7", |dirs, _| {
+        let actual = nu_error!(
+            cwd: dirs.root(),
+            "rm ."
+        );
+
+        assert!(actual.contains("may not be removed"));
+    })
+}
+
+#[test]
+fn errors_if_attempting_to_delete_two_dot_as_argument() {
+    Playground::setup("rm_test_8", |dirs, _| {
+        let actual = nu_error!(
+            cwd: dirs.root(),
+            "rm .."
+        );
+
+        assert!(actual.contains("may not be removed"));
+    })
+}