added if3 based on: Using if in a let Statement

exercises/if/if3.rs

@@ -0,0 +1,55 @@
+// if3.rs
+//
+// Execute `rustlings hint if3` or use the `hint` watch subcommand for a hint.
+
+// I AM NOT DONE
+
+pub fn animal_habitat(animal: &str) -> &'static str {
+    let identifier = if animal == "crab" {
+        1
+    } else if animal == "gopher" {
+        2.0
+    } else if animal == "snake" {
+        3
+    } else {
+        "Unknown"
+    };
+
+    // DO NOT CHANGE THIS STATEMENT BELOW
+    let habitat = if identifier == 1 {
+        "Beach"
+    } else if identifier == 2 {
+        "Burrow"
+    } else if identifier == 3 {
+        "Desert"
+    } else {
+        "Unknown"
+    };
+
+    habitat
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn gopher_lives_in_burrow() {
+        assert_eq!(animal_habitat("gopher"), "Burrow")
+    }
+
+    #[test]
+    fn snake_lives_in_desert() {
+        assert_eq!(animal_habitat("snake"), "Desert")
+    }
+
+    #[test]
+    fn crab_lives_on_beach() {
+        assert_eq!(animal_habitat("crab"), "Beach")
+    }
+
+    #[test]
+    fn unknown_animal() {
+        assert_eq!(animal_habitat("dinosaur"), "Unknown")
+    }
+}

info.toml

@@ -167,6 +167,13 @@ For that first compiler error, it's important in Rust that each conditional
 block returns the same type! To get the tests passing, you will need a couple
 conditions checking different input values."""
 
+[[exercises]]
+name = "if3"
+path = "exercises/if/if3.rs"
+mode = "test"
+hint = """
+In Rust, every arm of an `if` expression has to return the same type of value. Make sure the type is consistent across all arms."""
+
 # QUIZ 1
 
 [[exercises]]