Add two new tests; bit unrelated tbh.

tests/arg_rate_tests.rs

@@ -5,7 +5,7 @@ use predicates::prelude::*;
 
 // These tests are mostly here just to ensure that invalid results will be caught when passing arguments...
 
-// TODO: [TEST] Allow for release testing.
+// TODO: [TEST] Allow for release testing.  Do this with paths.
 
 //======================RATES======================//
 
@@ -71,3 +71,31 @@ fn test_invalid_rate() -> Result<(), Box<dyn std::error::Error>> {
 
     Ok(())
 }
+
+#[test]
+fn test_conflicting_temps() -> Result<(), Box<dyn std::error::Error>> {
+    Command::new(get_os_binary_loc())
+        .arg("-c")
+        .arg("-f")
+        .assert()
+        .failure()
+        .stderr(predicate::str::contains(
+            "cannot be used with one or more of the other specified arguments",
+        ));
+
+    Ok(())
+}
+
+#[test]
+fn test_conflicting_default_widget() -> Result<(), Box<dyn std::error::Error>> {
+    Command::new(get_os_binary_loc())
+        .arg("--cpu_default")
+        .arg("--disk_default")
+        .assert()
+        .failure()
+        .stderr(predicate::str::contains(
+            "cannot be used with one or more of the other specified arguments",
+        ));
+
+    Ok(())
+}