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/open.rs

@@ -0,0 +1,230 @@
+use nu_test_support::fs::Stub::FileWithContentToBeTrimmed;
+use nu_test_support::playground::Playground;
+use nu_test_support::{nu, nu_error, pipeline};
+
+#[test]
+fn parses_csv() {
+    Playground::setup("open_test_1", |dirs, sandbox| {
+        sandbox.with_files(vec![FileWithContentToBeTrimmed(
+            "nu.zion.csv",
+            r#"
+                    author,lang,source
+                    Jonathan Turner,Rust,New Zealand
+                    Andres N. Robalino,Rust,Ecuador
+                    Yehuda Katz,Rust,Estados Unidos
+                "#,
+        )]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                open nu.zion.csv
+                | where author == "Andres N. Robalino"
+                | get source
+                | echo $it
+            "#
+        ));
+
+        assert_eq!(actual, "Ecuador");
+    })
+}
+
+// sample.bson has the following format:
+// ━━━━━━━━━━┯━━━━━━━━━━━
+//  _id      │ root
+// ──────────┼───────────
+//  [object] │ [9 items]
+// ━━━━━━━━━━┷━━━━━━━━━━━
+//
+// the root value is:
+// ━━━┯━━━━━━━━━━━━━━━━━━━┯━━━━━━━━━━━━━━━━━━━━━━━━━┯━━━━━━━━━━┯━━━━━━━━━━
+//  # │ _id               │ a                       │ b        │ c
+// ───┼───────────────────┼─────────────────────────┼──────────┼──────────
+//  0 │ [object]          │       1.000000000000000 │ hello    │ [2 items]
+//  1 │ [object]          │       42.00000000000000 │ whel     │ hello
+//  2 │ [object]          │ [object]                │          │
+//  3 │ [object]          │                         │ [object] │
+//  4 │ [object]          │                         │          │ [object]
+//  5 │ [object]          │                         │          │ [object]
+//  6 │ [object]          │ [object]                │ [object] │
+//  7 │ [object]          │ <date value>            │ [object] │
+//  8 │ 1.000000          │ <decimal value>         │ [object] │
+//
+// The decimal value is supposed to be π, but is currently wrong due to
+// what appears to be an issue in the bson library that is under investigation.
+//
+
+#[test]
+fn parses_bson() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats",
+        "open sample.bson | get root | nth 0 | get b | echo $it"
+    );
+
+    assert_eq!(actual, "hello");
+}
+
+#[test]
+fn parses_more_bson_complexity() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            open sample.bson
+            | get root
+            | nth 6
+            | get b
+            | get '$binary_subtype'
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "function");
+}
+
+// sample.db has the following format:
+//
+// ━━━┯━━━━━━━━━━━━┯━━━━━━━━━━━━━━
+//  # │ table_name │ table_values
+// ───┼────────────┼──────────────
+//  0 │ strings    │ [6 items]
+//  1 │ ints       │ [5 items]
+//  2 │ floats     │ [4 items]
+// ━━━┷━━━━━━━━━━━━┷━━━━━━━━━━━━━━
+//
+// In this case, this represents a sqlite database
+// with three tables named `strings`, `ints`, and `floats`.
+// The table_values represent the values for the tables:
+//
+// ━━━━┯━━━━━━━┯━━━━━━━━━━┯━━━━━━┯━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+//  #  │ x     │ y        │ z    │ f
+// ────┼───────┼──────────┼──────┼──────────────────────────────────────────────────────────────────────
+//   0 │ hello │ <binary> │      │
+//   1 │ hello │ <binary> │      │
+//   2 │ hello │ <binary> │      │
+//   3 │ hello │ <binary> │      │
+//   4 │ world │ <binary> │      │
+//   5 │ world │ <binary> │      │
+//   6 │       │          │    1 │
+//   7 │       │          │   42 │
+//   8 │       │          │  425 │
+//   9 │       │          │ 4253 │
+//  10 │       │          │      │
+//  11 │       │          │      │                                                    3.400000000000000
+//  12 │       │          │      │                                                    3.141592650000000
+//  13 │       │          │      │                                                    23.00000000000000
+//  14 │       │          │      │ this string that doesn't really belong here but sqlite is what it is
+// ━━━━┷━━━━━━━┷━━━━━━━━━━┷━━━━━━┷━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+//
+// We can see here that each table has different columns. `strings` has `x` and `y`, while
+// `ints` has just `z`, and `floats` has only the column `f`. This means, in general, when working
+// with sqlite, one will want to select a single table, e.g.:
+//
+// open sample.db | nth 1 | get table_values
+// ━━━┯━━━━━━
+//  # │ z
+// ───┼──────
+//  0 │    1
+//  1 │   42
+//  2 │  425
+//  3 │ 4253
+//  4 │
+// ━━━┷━━━━━━
+
+#[test]
+fn parses_sqlite() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            open sample.db
+            | get table_values
+            | nth 2
+            | get x
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "hello");
+}
+
+#[test]
+fn parses_toml() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats",
+        "open cargo_sample.toml | get package.edition | echo $it"
+    );
+
+    assert_eq!(actual, "2018");
+}
+
+#[test]
+fn parses_tsv() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            open caco3_plastics.tsv
+            | first 1
+            | get origin
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "SPAIN")
+}
+
+#[test]
+fn parses_json() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            open sgml_description.json
+            | get glossary.GlossDiv.GlossList.GlossEntry.GlossSee
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "markup")
+}
+
+#[test]
+fn parses_xml() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats",
+        "open jonathan.xml | get rss.children.channel.children | get item.children | get link.children | echo $it"
+    );
+
+    assert_eq!(
+        actual,
+        "http://www.jonathanturner.org/2015/10/off-to-new-adventures.html"
+    )
+}
+
+#[test]
+fn parses_ini() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats",
+        "open sample.ini | get SectionOne.integer | echo $it"
+    );
+
+    assert_eq!(actual, "1234")
+}
+
+#[test]
+fn parses_utf16_ini() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats",
+        "open utf16.ini | get '.ShellClassInfo' | get IconIndex | echo $it"
+    );
+
+    assert_eq!(actual, "-236")
+}
+
+#[test]
+fn errors_if_file_not_found() {
+    let actual = nu_error!(
+        cwd: "tests/fixtures/formats",
+        "open i_dont_exist.txt"
+    );
+
+    assert!(actual.contains("File could not be opened"));
+    assert!(actual.contains("file not found"));
+}