uniq-by command (#7295)

New command `uniq-by` to get uniq results by column.

Closes https://github.com/nushell/nushell/issues/7109

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

@@ -0,0 +1,222 @@
+use nu_test_support::fs::Stub::FileWithContentToBeTrimmed;
+use nu_test_support::playground::Playground;
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn removes_duplicate_rows() {
+    Playground::setup("uniq_test_1", |dirs, sandbox| {
+        sandbox.with_files(vec![FileWithContentToBeTrimmed(
+            "los_tres_caballeros.csv",
+            r#"
+                first_name,last_name,rusty_at,type
+                Andrés,Robalino,10/11/2013,A
+                Afonso,Turner,10/12/2013,B
+                Yehuda,Katz,10/11/2013,A
+                Jonathan,Turner,11/12/2011,O
+            "#,
+        )]);
+
+        let actual = nu!(
+            cwd: dirs.test(), pipeline(
+            r#"
+                open los_tres_caballeros.csv
+                | uniq-by last_name
+                | length
+
+            "#
+        ));
+
+        assert_eq!(actual.out, "3");
+    })
+}
+
+#[test]
+fn uniq_when_keys_out_of_order() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            [{"a": "a", "b": [1,2,3]}, {"b": [1,2,3,4], "a": "a"}]
+            | uniq-by a
+        "#
+    ));
+    let expected = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+        echo [{"a": "a", "b": [1,2,3]}]
+        "#
+    ));
+
+    print!("{}", actual.out);
+    print!("{}", expected.out);
+    assert_eq!(actual.out, expected.out);
+    assert_eq!(actual.out, expected.out);
+}
+
+#[test]
+fn uniq_counting() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            ["A", "B", "A"]
+            | wrap item
+            | uniq-by item --count
+            | flatten
+            | where item == A
+            | get count
+            | get 0
+        "#
+    ));
+    assert_eq!(actual.out, "2");
+
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            echo ["A", "B", "A"]
+            | wrap item
+            | uniq-by item --count
+            | flatten
+            | where item == B
+            | get count
+            | get 0
+        "#
+    ));
+    assert_eq!(actual.out, "1");
+}
+
+#[test]
+fn uniq_unique() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            echo [1 2 3 4 1 5]
+            | wrap item
+            | uniq-by item --unique
+            | get item
+        "#
+    ));
+    let expected = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+        echo [2 3 4 5]
+        "#
+    ));
+    print!("{}", actual.out);
+    print!("{}", expected.out);
+    assert_eq!(actual.out, expected.out);
+}
+
+#[test]
+fn table() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            [[fruit day]; [apple monday] [apple friday] [Apple friday] [apple monday] [pear monday] [orange tuesday]]
+            | uniq-by fruit
+        "#
+    ));
+
+    let expected = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+        echo [[fruit day]; [apple monday] [Apple friday] [pear monday] [orange tuesday]]
+        "#
+    ));
+    print!("{}", actual.out);
+    print!("{}", expected.out);
+    assert_eq!(actual.out, expected.out);
+}
+
+#[test]
+fn uniq_by_multiple_columns() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            [[fruit day]; [apple monday] [apple friday] [Apple friday] [apple monday] [pear monday] [orange tuesday]]
+            | uniq-by fruit day
+        "#
+    ));
+
+    let expected = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+        echo [[fruit day]; [apple monday] [apple friday] [Apple friday] [pear monday] [orange tuesday]]
+        "#
+    ));
+    print!("{}", actual.out);
+    print!("{}", expected.out);
+    assert_eq!(actual.out, expected.out);
+}
+
+#[test]
+fn table_with_ignore_case() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            [[origin, people];
+                [World, (
+                    [[name, meal];
+                        ['Geremias', {plate: 'bitoque', carbs: 100}]
+                    ]
+                )],
+                [World, (
+                    [[name, meal];
+                        ['Martin', {plate: 'bitoque', carbs: 100}]
+                    ]
+                )],
+                [World, (
+                    [[name, meal];
+                        ['Geremias', {plate: 'Bitoque', carbs: 100}]
+                    ]
+                )],
+            ] | uniq-by people -i
+        "#
+    ));
+
+    let expected = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+        echo [[origin, people];
+                [World, (
+                    [[name, meal];
+                        ['Geremias', {plate: 'bitoque', carbs: 100}]
+                    ]
+                )],
+                [World, (
+                    [[name, meal];
+                        ['Martin', {plate: 'bitoque', carbs: 100}]
+                    ]
+                )],
+            ]
+        "#
+    ));
+
+    print!("{}", actual.out);
+    print!("{}", expected.out);
+    assert_eq!(actual.out, expected.out);
+    assert_eq!(actual.out, expected.out);
+}
+
+#[test]
+fn missing_parameter() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            [11 22 33] | uniq-by
+        "#
+    ));
+
+    assert!(actual.err.contains("missing parameter"));
+}
+
+#[test]
+fn wrong_column() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            [[fruit day]; [apple monday] [apple friday]]
+            | uniq-by column1
+        "#
+    ));
+
+    assert!(actual.err.contains("cannot find column 'column1'"));
+}