stdlib: refactor into a multi-module library (#8815)

crates/nu-std/tests/test_dirs.nu

@@ -0,0 +1,74 @@
+use std "assert length"
+use std "assert equal"
+
+def clean [path: path] {
+    cd $path
+    cd ..
+    rm -r $path
+}
+
+export def test_dirs_command [] {
+    # need some directories to play with
+    let base_path = ($nu.temp-path | path join $"test_dirs_(random uuid)")
+    let path_a = ($base_path | path join "a")
+    let path_b = ($base_path | path join "b")
+
+    try {
+        mkdir $base_path $path_a $path_b
+
+        cd $base_path
+        use std "dirs next"
+        use std "dirs prev"
+        use std "dirs add"
+        use std "dirs drop"
+        use std "dirs show"
+
+        assert length $env.DIRS_LIST 1 "list is just pwd after initialization"
+        assert equal $base_path $env.DIRS_LIST.0 "list is just pwd after initialization"
+
+        dirs next
+        assert equal $base_path $env.DIRS_LIST.0 "next wraps at end of list"
+
+        dirs prev
+        assert equal $base_path $env.DIRS_LIST.0 "prev wraps at top of list"
+
+        dirs add $path_b $path_a
+        assert equal $path_b $env.PWD "add changes PWD to first added dir"
+        assert length $env.DIRS_LIST 3 "add in fact adds to list"
+        assert equal $path_a $env.DIRS_LIST.2 "add in fact adds to list"
+
+        dirs next 2
+        assert equal $base_path $env.PWD "next wraps at end of list"
+
+        dirs prev 1
+        assert equal $path_a $env.PWD "prev wraps at start of list"
+
+        dirs drop
+        assert length $env.DIRS_LIST 2 "drop removes from list"
+        assert equal $base_path $env.PWD "drop changes PWD to next in list (after dropped element)"
+
+        assert equal (dirs show) [[active path]; [true $base_path] [false $path_b]] "show table contains expected information"
+    } catch { |error|
+        clean $base_path
+
+        let error = (
+            $error
+            | get debug
+            | str replace "{" "("
+            | str replace "}" ")"
+            | parse 'GenericError("{msg}", "{text}", Some(Span ( start: {start}, end: {end} )), {rest})'
+            | reject rest
+            | get 0
+        )
+        error make {
+            msg: $error.msg
+            label: {
+                text: $error.text
+                start: ($error.start | into int)
+                end: ($error.end | into int)
+            }
+        }
+    }
+
+    try { clean $base_path }
+}