correct clippy issues in test code

Author: Jonathan Creekmore

.travis.yml

@@ -10,11 +10,11 @@ script:
 
 matrix:
   include:
-  - rust: 1.31.1
+  - rust: 1.38.0
     env: CLIPPY=YESPLEASE
     before_script: rustup component add clippy-preview
     script: cargo clippy --all-targets --all -- -D warnings
-  - rust: 1.31.1
+  - rust: 1.38.0
     env: RUSTFMT=YESPLEASE
     before_script: rustup component add rustfmt-preview
     script: cargo fmt --all -- --check

src/human.rs

@@ -269,11 +269,13 @@ mod test_helper {
         pub fn target(&self) -> Target {
             Target::human(self.formatter())
         }
+    }
 
-        pub fn to_string(&self) -> String {
+    impl ::std::fmt::Display for TestTarget {
+        fn fmt(&self, f: &mut ::std::fmt::Formatter) -> Result<(), ::std::fmt::Error> {
             let target = self.buffer.0.clone();
             let buffer = target.read().unwrap();
-            String::from_utf8_lossy(buffer.as_slice()).to_string()
+            write!(f, "{}", String::from_utf8_lossy(buffer.as_slice()))
         }
     }
 }

src/json.rs

@@ -279,11 +279,13 @@ mod test_helper {
         pub fn target(&self) -> Target {
             Target::json(self.formatter())
         }
+    }
 
-        pub fn to_string(&self) -> String {
+    impl ::std::fmt::Display for TestTarget {
+        fn fmt(&self, f: &mut ::std::fmt::Formatter) -> Result<(), ::std::fmt::Error> {
             let target = self.buffer.0.clone();
             let buffer = target.read().unwrap();
-            String::from_utf8_lossy(buffer.as_slice()).to_string()
+            write!(f, "{}", String::from_utf8_lossy(buffer.as_slice()))
         }
     }
 }