fix: Update Module::is_empty to check value of segments (#332)

Previously, a set of empty segments would cause the module to print. This changes the 
logic of Module::is_empty to check that all the segments are empty instead.

src/module.rs

@@ -74,9 +74,9 @@ impl<'a> Module<'a> {
         self.segments.last_mut().unwrap()
     }
 
-    /// Whether a module has any segments
+    /// Whether a module has non-empty segments
     pub fn is_empty(&self) -> bool {
-        self.segments.is_empty()
+        self.segments.iter().all(|segment| segment.is_empty())
     }
 
     /// Get the module's prefix
@@ -261,3 +261,38 @@ impl fmt::Display for Affix {
         write!(f, "{}", self.ansi_string())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_module_is_empty_with_no_segments() {
+        let name = "unit_test";
+        let module = Module {
+            config: None,
+            _name: name.to_string(),
+            style: Style::default(),
+            prefix: Affix::default_prefix(name),
+            segments: Vec::new(),
+            suffix: Affix::default_suffix(name),
+        };
+
+        assert!(module.is_empty());
+    }
+
+    #[test]
+    fn test_module_is_empty_with_all_empty_segments() {
+        let name = "unit_test";
+        let module = Module {
+            config: None,
+            _name: name.to_string(),
+            style: Style::default(),
+            prefix: Affix::default_prefix(name),
+            segments: vec![Segment::new("test_segment")],
+            suffix: Affix::default_suffix(name),
+        };
+
+        assert!(module.is_empty());
+    }
+}

src/segment.rs

@@ -52,6 +52,11 @@ impl Segment {
             None => ANSIString::from(&self.value),
         }
     }
+
+    /// Determines if the segment contains a value.
+    pub fn is_empty(&self) -> bool {
+        self.value.trim().is_empty()
+    }
 }
 
 impl fmt::Display for Segment {