Command tests (#922)

* WIP command tests

* Finish marking todo tests

* update

* update

* Windows cd test ignoring

crates/nu-command/tests/commands/zip.rs

@@ -0,0 +1,73 @@
+use nu_test_support::fs::Stub::FileWithContent;
+use nu_test_support::playground::Playground;
+use nu_test_support::{nu, pipeline};
+
+const ZIP_POWERED_TEST_ASSERTION_SCRIPT: &str = r#"
+def expect [
+    left,
+    right,
+    --to-eq
+] {
+    $left | zip { $right } | all? {
+        $it.name.0 == $it.name.1 && $it.commits.0 == $it.commits.1
+    }
+}
+
+def add-commits [n] {
+  each {
+    let contributor = $it;
+    let name = $it.name;
+    let commits = $it.commits;
+
+    $contributor | merge {
+      [[commits]; [($commits + $n)]]
+    }
+  }
+}
+"#;
+
+// FIXME: jt: needs more work
+#[ignore]
+#[test]
+fn zips_two_tables() {
+    Playground::setup("zip_test_1", |dirs, nu| {
+        nu.with_files(vec![FileWithContent(
+            "zip_test.nu",
+            &format!("{}\n", ZIP_POWERED_TEST_ASSERTION_SCRIPT),
+        )]);
+
+        let actual = nu!(
+            cwd: ".", pipeline(
+            &format!(
+                r#"
+                source {} ;
+        
+                let contributors = ([
+                  [name, commits];
+                  [andres,    10]
+                  [    jt,    20]
+                ]);
+                        
+                let actual = ($contributors | add-commits 10);
+                        
+                expect $actual --to-eq [[name, commits]; [andres, 20] [jt, 30]]
+                "#,
+                dirs.test().join("zip_test.nu").display()
+            )
+        ));
+
+        assert_eq!(actual.out, "true");
+    })
+}
+
+#[test]
+fn zips_two_lists() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+                echo [0 2 4 6 8] | zip [1 3 5 7 9] | flatten | into string | str collect '-'
+            "#
+    ));
+
+    assert_eq!(actual.out, "0-1-2-3-4-5-6-7-8-9");
+}