This commit is the continuing phase of extracting functionality to subcrates. We extract test helpers and begin to change Nu shell's test organization along with it.

tests/commands/first.rs

@@ -0,0 +1,70 @@
+use test_support::fs::Stub::EmptyFile;
+use test_support::playground::Playground;
+use test_support::{nu, pipeline};
+
+#[test]
+fn gets_first_rows_by_amount() {
+    Playground::setup("first_test_1", |dirs, sandbox| {
+        sandbox.with_files(vec![
+            EmptyFile("los.txt"),
+            EmptyFile("tres.txt"),
+            EmptyFile("amigos.txt"),
+            EmptyFile("arepas.clu"),
+        ]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                ls
+                | first 3
+                | count
+                | echo $it
+            "#
+        ));
+
+        assert_eq!(actual, "3");
+    })
+}
+
+#[test]
+fn gets_all_rows_if_amount_higher_than_all_rows() {
+    Playground::setup("first_test_2", |dirs, sandbox| {
+        sandbox.with_files(vec![
+            EmptyFile("los.txt"),
+            EmptyFile("tres.txt"),
+            EmptyFile("amigos.txt"),
+            EmptyFile("arepas.clu"),
+        ]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                ls
+                | first 99
+                | count
+                | echo $it
+            "#
+        ));
+
+        assert_eq!(actual, "4");
+    })
+}
+
+#[test]
+fn gets_first_row_when_no_amount_given() {
+    Playground::setup("first_test_3", |dirs, sandbox| {
+        sandbox.with_files(vec![EmptyFile("caballeros.txt"), EmptyFile("arepas.clu")]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                ls
+                | first
+                | count
+                | echo $it
+            "#
+        ));
+
+        assert_eq!(actual, "1");
+    })
+}