Added tests to constant kernel

src/fitter/recursive.rs

@@ -227,15 +227,12 @@ impl Fitter for RecursiveFitter {
         let mut ms = Vec::new();
         let mut vs = Vec::new();
 
-        let locations = ts
-            .iter()
-            .map(|t| {
-                self.ts
-                    .iter()
-                    .position(|tc| t <= tc)
-                    .unwrap_or_else(|| self.ts.len())
-            })
-            .collect::<Vec<_>>();
+        let locations = ts.iter().map(|t| {
+            self.ts
+                .iter()
+                .position(|tc| t <= tc)
+                .unwrap_or_else(|| self.ts.len())
+        });
 
         for (i, nxt) in locations.into_iter().enumerate() {
             if nxt == self.ts.len() {