Add from-eml command (#1656)

* from-eml initial ver

* Adding tests for `from-eml`

* Add eml to prepares_and_decorates_filesystem_source_files

* Sort the file order

Co-authored-by: Jonathan Turner <jonathandturner@users.noreply.github.com>

crates/nu-cli/tests/format_conversions/eml.rs

@@ -0,0 +1,84 @@
+use nu_test_support::{nu, pipeline};
+
+const TEST_CWD: &str = "tests/fixtures/formats";
+
+// The To field in this email is just "username@domain.com", which gets parsed out as the Address. The Name is empty.
+#[test]
+fn from_eml_get_to_field() {
+    let actual = nu!(
+        cwd: TEST_CWD,
+        pipeline(
+            r#"
+            open sample.eml
+            | get To
+            | get Address
+            | echo $it
+        "#
+        )
+    );
+
+    assert_eq!(actual, "username@domain.com");
+
+    let actual = nu!(
+        cwd: TEST_CWD,
+        pipeline(
+            r#"
+            open sample.eml
+            | get To
+            | get Name
+            | echo $it
+        "#
+        )
+    );
+
+    assert_eq!(actual, "");
+}
+
+// The Reply-To field in this email is "aw-confirm@ebay.com" <aw-confirm@ebay.com>, meaning both the Name and Address values are identical.
+#[test]
+fn from_eml_get_replyto_field() {
+    let actual = nu!(
+        cwd: TEST_CWD,
+        pipeline(
+            r#"
+            open sample.eml
+            | get Reply-To
+            | get Address
+            | echo $it
+        "#
+        )
+    );
+
+    assert_eq!(actual, "aw-confirm@ebay.com");
+
+    let actual = nu!(
+        cwd: TEST_CWD,
+        pipeline(
+            r#"
+            open sample.eml
+            | get Reply-To
+            | get Name
+            | echo $it
+        "#
+        )
+    );
+
+    assert_eq!(actual, "aw-confirm@ebay.com");
+}
+
+// The Reply-To field in this email is "aw-confirm@ebay.com" <aw-confirm@ebay.com>, meaning both the Name and Address values are identical.
+#[test]
+fn from_eml_get_subject_field() {
+    let actual = nu!(
+        cwd: TEST_CWD,
+        pipeline(
+            r#"
+            open sample.eml
+            | get Subject
+            | echo $it
+        "#
+        )
+    );
+
+    assert_eq!(actual, "Billing Issues");
+}

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

@@ -1,5 +1,6 @@
 mod bson;
 mod csv;
+mod eml;
 mod html;
 mod ics;
 mod json;