Rows and values can be checked for emptiness. Allows to set a value if desired. (#1665)

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

@@ -0,0 +1,96 @@
+use nu_test_support::fs::Stub::FileWithContentToBeTrimmed;
+use nu_test_support::playground::Playground;
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn adds_value_provided_if_column_is_empty() {
+    Playground::setup("is_empty_test_1", |dirs, sandbox| {
+        sandbox.with_files(vec![FileWithContentToBeTrimmed(
+            "likes.csv",
+            r#"
+                first_name,last_name,rusty_at,likes
+                Andrés,Robalino,10/11/2013,1
+                Jonathan,Turner,10/12/2013,1
+                Jason,Gedge,10/11/2013,1
+                Yehuda,Katz,10/11/2013,
+            "#,
+        )]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                open likes.csv
+                | empty? likes 1
+                | get likes
+                | sum
+                | echo $it
+            "#
+        ));
+
+        assert_eq!(actual, "4");
+    })
+}
+
+#[test]
+fn adds_value_provided_for_columns_that_are_empty() {
+    Playground::setup("is_empty_test_2", |dirs, sandbox| {
+        sandbox.with_files(vec![FileWithContentToBeTrimmed(
+            "checks.json",
+            r#"
+                [
+                    {"boost": 1, "check": []},
+                    {"boost": 1, "check": ""},
+                    {"boost": 1, "check": {}},
+                    {"boost": null, "check": ["" {} [] ""]}
+                ]
+                
+            "#,
+        )]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                open checks.json
+                | empty? boost check 1
+                | get boost check
+                | sum
+                | echo $it
+            "#
+        ));
+
+        assert_eq!(actual, "8");
+    })
+}
+
+#[test]
+fn value_emptiness_check() {
+    Playground::setup("is_empty_test_3", |dirs, sandbox| {
+        sandbox.with_files(vec![FileWithContentToBeTrimmed(
+            "checks.json",
+            r#"
+                {
+                    "are_empty": [
+                        {"check": []},
+                        {"check": ""},
+                        {"check": {}},
+                        {"check": ["" {} [] ""]}
+                    ]
+                }
+            "#,
+        )]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                open checks.json
+                | get are_empty.check
+                | empty?
+                | where $it
+                | count
+                | echo $it
+            "#
+        ));
+
+        assert_eq!(actual, "4");
+    })
+}

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

@@ -16,6 +16,7 @@ mod group_by;
 mod headers;
 mod histogram;
 mod insert;
+mod is_empty;
 mod last;
 mod lines;
 mod ls;