Add fuzz tests for unfill and refill

Thanks to @A-Walrus in #466 for the idea.

.github/workflows/build.yml

@@ -120,6 +120,8 @@ jobs:
           - wrap_first_fit
           - wrap_optimal_fit
           - wrap_optimal_fit_usize
+          - unfill
+          - refill
 
     steps:
       - name: Checkout repository

fuzz/Cargo.toml

@@ -47,3 +47,15 @@ name = "wrap_optimal_fit_usize"
 path = "fuzz_targets/wrap_optimal_fit_usize.rs"
 test = false
 doc = false
+
+[[bin]]
+name = "refill"
+path = "fuzz_targets/refill.rs"
+test = false
+doc = false
+
+[[bin]]
+name = "unfill"
+path = "fuzz_targets/unfill.rs"
+test = false
+doc = false

fuzz/fuzz_targets/refill.rs

@@ -0,0 +1,6 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|input: (String, usize)| {
+    let _ = textwrap::refill(&input.0, input.1);
+});

fuzz/fuzz_targets/unfill.rs

@@ -0,0 +1,6 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|input: String| {
+    let _ = textwrap::unfill(&input);
+});