diff --git a/src/parser/comment.rs b/src/parser/comment.rs
index c301a5fe..81628774 100644
--- a/src/parser/comment.rs
+++ b/src/parser/comment.rs
@@ -69,22 +69,21 @@ fn comment_line<'r, 's>(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::parser::parser_context::ContextElement;
     use crate::parser::parser_context::ContextTree;
     use crate::parser::parser_with_context::parser_with_context;
 
     #[test]
     fn require_space_after_hash() {
-        let input = "# Comment line
+        let input = OrgSource::new(
+            "# Comment line
 #not a comment
-# Comment again";
+# Comment again",
+        );
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let comment_matcher = parser_with_context!(comment)(&document_context);
+        let comment_matcher = parser_with_context!(comment)(&initial_context);
         let (remaining, first_comment) = comment_matcher(input).expect("Parse first comment");
         assert_eq!(
-            remaining,
+            Into::<&str>::into(remaining),
             r#"#not a comment
 # Comment again"#
         );
diff --git a/src/parser/footnote_definition.rs b/src/parser/footnote_definition.rs
index 738c3240..91eceb23 100644
--- a/src/parser/footnote_definition.rs
+++ b/src/parser/footnote_definition.rs
@@ -111,27 +111,26 @@ fn footnote_definition_end<'r, 's>(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::parser::parser_context::ContextElement;
     use crate::parser::parser_context::ContextTree;
     use crate::parser::parser_with_context::parser_with_context;
     use crate::parser::Source;
 
     #[test]
     fn two_paragraphs() {
-        let input = "[fn:1] A footnote.
+        let input = OrgSource::new(
+            "[fn:1] A footnote.
 
 [fn:2] A multi-
 
-line footnote.";
+line footnote.",
+        );
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let footnote_definition_matcher = parser_with_context!(element(true))(&document_context);
+        let footnote_definition_matcher = parser_with_context!(element(true))(&initial_context);
         let (remaining, first_footnote_definition) =
             footnote_definition_matcher(input).expect("Parse first footnote_definition");
         let (remaining, second_footnote_definition) =
             footnote_definition_matcher(remaining).expect("Parse second footnote_definition.");
-        assert_eq!(remaining, "");
+        assert_eq!(Into::<&str>::into(remaining), "");
         assert_eq!(
             first_footnote_definition.get_source(),
             "[fn:1] A footnote.
@@ -148,19 +147,19 @@ line footnote."
 
     #[test]
     fn multiline_break() {
-        let input = "[fn:2] A multi-
+        let input = OrgSource::new(
+            "[fn:2] A multi-
 
 line footnote.
 
 
-not in the footnote.";
+not in the footnote.",
+        );
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let footnote_definition_matcher = parser_with_context!(element(true))(&document_context);
+        let footnote_definition_matcher = parser_with_context!(element(true))(&initial_context);
         let (remaining, first_footnote_definition) =
             footnote_definition_matcher(input).expect("Parse first footnote_definition");
-        assert_eq!(remaining, "not in the footnote.");
+        assert_eq!(Into::<&str>::into(remaining), "not in the footnote.");
         assert_eq!(
             first_footnote_definition.get_source(),
             "[fn:2] A multi-
diff --git a/src/parser/org_source.rs b/src/parser/org_source.rs
index 5ebc0377..1aecc014 100644
--- a/src/parser/org_source.rs
+++ b/src/parser/org_source.rs
@@ -45,7 +45,7 @@ impl<'s> OrgSource<'s> {
     }
 
     pub fn get_preceding_character(&self) -> Option<char> {
-        todo!()
+        self.preceding_character
     }
 
     pub fn is_at_start_of_line(&self) -> bool {
@@ -357,4 +357,12 @@ mod tests {
         assert_eq!(input.slice(6..).is_at_start_of_line(), true);
         assert_eq!(input.slice(6..).slice(10..).is_at_start_of_line(), false);
     }
+
+    #[test]
+    fn preceding_character_unicode() {
+        let input = OrgSource::new("🧡💛💚💙💜");
+        assert_eq!(input.get_preceding_character(), None);
+        assert_eq!(input.slice(8..).get_preceding_character(), Some('💛'));
+    }
+
 }
diff --git a/src/parser/paragraph.rs b/src/parser/paragraph.rs
index 65f11b74..8f91e121 100644
--- a/src/parser/paragraph.rs
+++ b/src/parser/paragraph.rs
@@ -69,22 +69,20 @@ fn paragraph_end<'r, 's>(
 #[cfg(test)]
 mod tests {
     use crate::parser::element_parser::element;
-    use crate::parser::parser_context::ContextElement;
+    use crate::parser::org_source::OrgSource;
     use crate::parser::parser_context::ContextTree;
     use crate::parser::parser_with_context::parser_with_context;
     use crate::parser::source::Source;
 
     #[test]
     fn two_paragraphs() {
-        let input = "foo bar baz\n\nlorem ipsum";
+        let input = OrgSource::new("foo bar baz\n\nlorem ipsum");
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let paragraph_matcher = parser_with_context!(element(true))(&document_context);
+        let paragraph_matcher = parser_with_context!(element(true))(&initial_context);
         let (remaining, first_paragraph) = paragraph_matcher(input).expect("Parse first paragraph");
         let (remaining, second_paragraph) =
             paragraph_matcher(remaining).expect("Parse second paragraph.");
-        assert_eq!(remaining, "");
+        assert_eq!(Into::<&str>::into(remaining), "");
         assert_eq!(first_paragraph.get_source(), "foo bar baz\n\n");
         assert_eq!(second_paragraph.get_source(), "lorem ipsum");
     }
diff --git a/src/parser/plain_list.rs b/src/parser/plain_list.rs
index b3edfae8..810784e5 100644
--- a/src/parser/plain_list.rs
+++ b/src/parser/plain_list.rs
@@ -239,67 +239,56 @@ fn get_context_item_indent<'r, 's>(context: Context<'r, 's>) -> Option<&'r usize
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::parser::parser_context::ContextElement;
     use crate::parser::parser_context::ContextTree;
     use crate::parser::parser_with_context::parser_with_context;
     use crate::parser::Source;
 
     #[test]
     fn plain_list_item_empty() {
-        let input = "1.";
+        let input = OrgSource::new("1.");
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let plain_list_item_matcher = parser_with_context!(plain_list_item)(&document_context);
+        let plain_list_item_matcher = parser_with_context!(plain_list_item)(&initial_context);
         let (remaining, result) = plain_list_item_matcher(input).unwrap();
-        assert_eq!(remaining, "");
+        assert_eq!(Into::<&str>::into(remaining), "");
         assert_eq!(result.source, "1.");
     }
 
     #[test]
     fn plain_list_item_simple() {
-        let input = "1. foo";
+        let input = OrgSource::new("1. foo");
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let plain_list_item_matcher = parser_with_context!(plain_list_item)(&document_context);
+        let plain_list_item_matcher = parser_with_context!(plain_list_item)(&initial_context);
         let (remaining, result) = plain_list_item_matcher(input).unwrap();
-        assert_eq!(remaining, "");
+        assert_eq!(Into::<&str>::into(remaining), "");
         assert_eq!(result.source, "1. foo");
     }
 
     #[test]
     fn plain_list_empty() {
-        let input = "1.";
+        let input = OrgSource::new("1.");
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let plain_list_matcher = parser_with_context!(plain_list)(&document_context);
+        let plain_list_matcher = parser_with_context!(plain_list)(&initial_context);
         let (remaining, result) = plain_list_matcher(input).unwrap();
-        assert_eq!(remaining, "");
+        assert_eq!(Into::<&str>::into(remaining), "");
         assert_eq!(result.source, "1.");
     }
 
     #[test]
     fn plain_list_simple() {
-        let input = "1. foo";
+        let input = OrgSource::new("1. foo");
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let plain_list_matcher = parser_with_context!(plain_list)(&document_context);
+        let plain_list_matcher = parser_with_context!(plain_list)(&initial_context);
         let (remaining, result) = plain_list_matcher(input).unwrap();
-        assert_eq!(remaining, "");
+        assert_eq!(Into::<&str>::into(remaining), "");
         assert_eq!(result.source, "1. foo");
     }
 
     #[test]
     fn plain_list_cant_start_line_with_asterisk() {
         // Plain lists with an asterisk bullet must be indented or else they would be a headline
-        let input = "* foo";
+        let input = OrgSource::new("* foo");
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let plain_list_matcher = parser_with_context!(plain_list)(&document_context);
+        let plain_list_matcher = parser_with_context!(plain_list)(&initial_context);
         let result = plain_list_matcher(input);
         assert!(result.is_err());
     }
@@ -307,32 +296,30 @@ mod tests {
     #[test]
     fn indented_can_start_line_with_asterisk() {
         // Plain lists with an asterisk bullet must be indented or else they would be a headline
-        let input = " * foo";
+        let input = OrgSource::new(" * foo");
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let plain_list_matcher = parser_with_context!(plain_list)(&document_context);
+        let plain_list_matcher = parser_with_context!(plain_list)(&initial_context);
         let result = plain_list_matcher(input);
         assert!(result.is_ok());
     }
 
     #[test]
     fn two_blank_lines_ends_list() {
-        let input = r#"1. foo
+        let input = OrgSource::new(
+            r#"1. foo
 2. bar
    baz
 3. lorem
 
 
    ipsum
-"#;
+"#,
+        );
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let plain_list_matcher = parser_with_context!(element(true))(&document_context);
+        let plain_list_matcher = parser_with_context!(element(true))(&initial_context);
         let (remaining, result) =
             plain_list_matcher(input).expect("Should parse the plain list successfully.");
-        assert_eq!(remaining, "   ipsum\n");
+        assert_eq!(Into::<&str>::into(remaining), "   ipsum\n");
         assert_eq!(
             result.get_source(),
             r#"1. foo
@@ -347,18 +334,18 @@ mod tests {
 
     #[test]
     fn two_blank_lines_ends_nested_list() {
-        let input = r#"1. foo
+        let input = OrgSource::new(
+            r#"1. foo
    1. bar
 
 
-baz"#;
+baz"#,
+        );
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let plain_list_matcher = parser_with_context!(element(true))(&document_context);
+        let plain_list_matcher = parser_with_context!(element(true))(&initial_context);
         let (remaining, result) =
             plain_list_matcher(input).expect("Should parse the plain list successfully.");
-        assert_eq!(remaining, "baz");
+        assert_eq!(Into::<&str>::into(remaining), "baz");
         assert_eq!(
             result.get_source(),
             r#"1. foo
@@ -371,7 +358,8 @@ baz"#;
 
     #[test]
     fn interior_trailing_whitespace() {
-        let input = r#"1. foo
+        let input = OrgSource::new(
+            r#"1. foo
 
    bar
 
@@ -382,14 +370,13 @@ baz"#;
    ipsum
 
 
-dolar"#;
+dolar"#,
+        );
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let plain_list_matcher = parser_with_context!(element(true))(&document_context);
+        let plain_list_matcher = parser_with_context!(element(true))(&initial_context);
         let (remaining, result) =
             plain_list_matcher(input).expect("Should parse the plain list successfully.");
-        assert_eq!(remaining, "dolar");
+        assert_eq!(Into::<&str>::into(remaining), "dolar");
         assert_eq!(
             result.get_source(),
             r#"1. foo
diff --git a/src/parser/plain_text.rs b/src/parser/plain_text.rs
index bdc9deb9..7d0423d7 100644
--- a/src/parser/plain_text.rs
+++ b/src/parser/plain_text.rs
@@ -69,20 +69,17 @@ mod tests {
     use nom::combinator::map;
 
     use super::*;
-    use crate::parser::parser_context::ContextElement;
     use crate::parser::parser_context::ContextTree;
     use crate::parser::parser_with_context::parser_with_context;
     use crate::parser::source::Source;
 
     #[test]
     fn plain_text_simple() {
-        let input = "foobarbaz";
+        let input = OrgSource::new("foobarbaz");
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
-        let document_context =
-            initial_context.with_additional_node(ContextElement::DocumentRoot(input));
-        let plain_text_matcher = parser_with_context!(plain_text)(&document_context);
+        let plain_text_matcher = parser_with_context!(plain_text)(&initial_context);
         let (remaining, result) = map(plain_text_matcher, Object::PlainText)(input).unwrap();
-        assert_eq!(remaining, "");
-        assert_eq!(result.get_source(), input);
+        assert_eq!(Into::<&str>::into(remaining), "");
+        assert_eq!(result.get_source(), Into::<&str>::into(input));
     }
 }
diff --git a/src/parser/radio_link.rs b/src/parser/radio_link.rs
index 1bef2340..e52d2708 100644
--- a/src/parser/radio_link.rs
+++ b/src/parser/radio_link.rs
@@ -144,11 +144,10 @@ mod tests {
 
     #[test]
     fn plain_text_radio_target() {
-        let input = "foo bar baz";
+        let input = OrgSource::new("foo bar baz");
         let radio_target_match = vec![Object::PlainText(PlainText { source: "bar" })];
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
         let document_context = initial_context
-            .with_additional_node(ContextElement::DocumentRoot(input))
             .with_additional_node(ContextElement::RadioTarget(vec![&radio_target_match]));
         let paragraph_matcher = parser_with_context!(element(true))(&document_context);
         let (remaining, first_paragraph) = paragraph_matcher(input).expect("Parse first paragraph");
@@ -173,14 +172,13 @@ mod tests {
 
     #[test]
     fn bold_radio_target() {
-        let input = "foo *bar* baz";
+        let input = OrgSource::new("foo *bar* baz");
         let radio_target_match = vec![Object::Bold(Bold {
             source: "*bar*",
             children: vec![Object::PlainText(PlainText { source: "bar" })],
         })];
         let initial_context: ContextTree<'_, '_> = ContextTree::new();
         let document_context = initial_context
-            .with_additional_node(ContextElement::DocumentRoot(input))
             .with_additional_node(ContextElement::RadioTarget(vec![&radio_target_match]));
         let paragraph_matcher = parser_with_context!(element(true))(&document_context);
         let (remaining, first_paragraph) =
diff --git a/src/parser/util.rs b/src/parser/util.rs
index a62197be..2306cd5c 100644
--- a/src/parser/util.rs
+++ b/src/parser/util.rs
@@ -206,18 +206,3 @@ pub fn not_yet_implemented() -> Res<OrgSource<'static>, ()> {
         "Not implemented yet.".into(),
     ))));
 }
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn get_one_before_unicode() {
-        let input = "🧡💛💚💙💜";
-        let (green_heart_index, _) = input.char_indices().skip(2).next().unwrap();
-        let starting_with_green_heart = &input[green_heart_index..];
-        let yellow_heart = get_one_before(input, starting_with_green_heart).unwrap();
-        assert!(is_slice_of(input, yellow_heart));
-        assert_eq!(yellow_heart, "💛");
-    }
-}