add tests for history::find

src/history/find.rs

@@ -15,3 +15,86 @@ pub fn find(link: &Link, file_name: &str) -> Result<bool> {
     }
     Ok(false) // is not already downloaded
 }
+
+#[cfg(test)]
+mod test {
+    use crate::{history::Link, test_utils::create_text_file};
+
+    use super::*;
+    #[test]
+    fn true_if_line_exists() -> Result<()> {
+        //given
+        let (dir, file_name) =
+            create_text_file("file", include_bytes!("../../test/data/with-llamma.txt"))?;
+        let link = Link {
+            href: "llamma".to_string(),
+            rel: "".to_string(),
+            hreflang: None,
+            mime_type: None,
+            title: None,
+            length: None,
+        };
+
+        //when
+        let result = find(&link, &file_name)?;
+
+        //then
+        drop(dir);
+
+        assert_eq!(result, true);
+
+        Ok(())
+    }
+
+    #[test]
+    fn false_if_line_absent() -> Result<()> {
+        //given
+        let (dir, file_name) =
+            create_text_file("file", include_bytes!("../../test/data/without-llamma.txt"))?;
+        let link = Link {
+            href: "llamma".to_string(),
+            rel: "".to_string(),
+            hreflang: None,
+            mime_type: None,
+            title: None,
+            length: None,
+        };
+
+        //when
+        let result = find(&link, &file_name)?;
+
+        //then
+        drop(dir);
+
+        assert_eq!(result, false);
+
+        Ok(())
+    }
+
+    #[test]
+    fn false_if_embedded_within_line() -> Result<()> {
+        //given
+        let (dir, file_name) = create_text_file(
+            "file",
+            include_bytes!("../../test/data/with-embedded-llamma.txt"),
+        )?;
+        let link = Link {
+            href: "llamma".to_string(),
+            rel: "".to_string(),
+            hreflang: None,
+            mime_type: None,
+            title: None,
+            length: None,
+        };
+
+        //when
+        let result = find(&link, &file_name)?;
+
+        //then
+        drop(dir);
+
+        assert_eq!(result, false);
+
+        Ok(())
+    }
+}

test/data/with-embedded-llamma.txt

@@ -0,0 +1,3 @@
+this is a text file
+embedded llamma
+it has three lines

test/data/with-llamma.txt

@@ -0,0 +1,3 @@
+this is a text file
+llamma
+it has three lines

test/data/without-llamma.txt

@@ -0,0 +1,2 @@
+this is a text file
+it has three lines