Change layout panics to errors

* Adjust and add tests for the change

10 files changed, 354 insertions, 84 deletions

diff --git a/example/multiple_tabs_layout.yaml b/example/multiple_tabs_layout.yaml
index 40689a969..6c4d15980 100644
--- a/example/multiple_tabs_layout.yaml
+++ b/example/multiple_tabs_layout.yaml
@@ -17,6 +17,7 @@ parts:
         split_size:
           Percent: 50
     - direction: Vertical
+    - direction: Vertical
       parts:
         - direction: Vertical
           split_size:
diff --git a/zellij-utils/src/input/config.rs b/zellij-utils/src/input/config.rs
index 6a65109a7..930fe07af 100644
--- a/zellij-utils/src/input/config.rs
+++ b/zellij-utils/src/input/config.rs
@@ -45,6 +45,9 @@ pub enum ConfigError {
     IoPath(io::Error, PathBuf),
     // Internal Deserialization Error
     FromUtf8(std::string::FromUtf8Error),
+    // Missing the tab section in the layout.
+    Layout(LayoutMissingTabSectionError),
+    LayoutPartAndTab(LayoutPartAndTabError),
 }
 
 impl Default for Config {
@@ -129,6 +132,75 @@ impl Config {
     }
 }
 
+// TODO: Split errors up into separate modules
+#[derive(Debug, Clone)]
+pub struct LayoutMissingTabSectionError;
+#[derive(Debug, Clone)]
+pub struct LayoutPartAndTabError;
+
+impl fmt::Display for LayoutMissingTabSectionError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "MissingTabSectionError:
+There needs to be exactly one `tabs` section specified in the layout file, for example:
+---
+direction: Horizontal
+parts:
+  - direction: Vertical
+  - direction: Vertical
+    tabs:
+      - direction: Vertical
+      - direction: Vertical
+  - direction: Vertical
+"
+        )
+    }
+}
+
+impl std::error::Error for LayoutMissingTabSectionError {
+    fn description(&self) -> &str {
+        "One tab must be specified per Layout."
+    }
+}
+
+impl fmt::Display for LayoutPartAndTabError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "LayoutPartAndTabError:
+The `tabs` and `parts` section should not be specified on the same level in the layout file, for example:
+---
+direction: Horizontal
+parts:
+  - direction: Vertical
+  - direction: Vertical
+tabs:
+  - direction: Vertical
+  - direction: Vertical
+  - direction: Vertical
+
+should rather be specified as:
+---
+direction: Horizontal
+parts:
+  - direction: Vertical
+  - direction: Vertical
+    tabs:
+      - direction: Vertical
+      - direction: Vertical
+      - direction: Vertical
+"
+        )
+    }
+}
+
+impl std::error::Error for LayoutPartAndTabError {
+    fn description(&self) -> &str {
+        "The `tabs` and parts section should not be specified on the same level."
+    }
+}
+
 impl Display for ConfigError {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         match self {
@@ -138,6 +210,12 @@ impl Display for ConfigError {
             }
             ConfigError::Serde(ref err) => write!(formatter, "Deserialization error: {}", err),
             ConfigError::FromUtf8(ref err) => write!(formatter, "FromUtf8Error: {}", err),
+            ConfigError::Layout(ref err) => {
+                write!(formatter, "There was an error in the layout file, {}", err)
+            }
+            ConfigError::LayoutPartAndTab(ref err) => {
+                write!(formatter, "There was an error in the layout file, {}", err)
+            }
         }
     }
 }
@@ -149,6 +227,8 @@ impl std::error::Error for ConfigError {
             ConfigError::IoPath(ref err, _) => Some(err),
             ConfigError::Serde(ref err) => Some(err),
             ConfigError::FromUtf8(ref err) => Some(err),
+            ConfigError::Layout(ref err) => Some(err),
+            ConfigError::LayoutPartAndTab(ref err) => Some(err),
         }
     }
 }
@@ -171,6 +251,18 @@ impl From<std::string::FromUtf8Error> for ConfigError {
     }
 }
 
+impl From<LayoutMissingTabSectionError> for ConfigError {
+    fn from(err: LayoutMissingTabSectionError) -> ConfigError {
+        ConfigError::Layout(err)
+    }
+}
+
+impl From<LayoutPartAndTabError> for ConfigError {
+    fn from(err: LayoutPartAndTabError) -> ConfigError {
+        ConfigError::LayoutPartAndTab(err)
+    }
+}
+
 // The unit test location.
 #[cfg(test)]
 mod config_test {
diff --git a/zellij-utils/src/input/layout.rs b/zellij-utils/src/input/layout.rs
index 887350fb0..c795cb55b 100644
--- a/zellij-utils/src/input/layout.rs
+++ b/zellij-utils/src/input/layout.rs
@@ -20,6 +20,8 @@ use std::path::{Path, PathBuf};
 use std::vec::Vec;
 use std::{fs::File, io::prelude::*};
 
+use super::config::{LayoutMissingTabSectionError, LayoutPartAndTabError};
+
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq)]
 #[serde(crate = "self::serde")]
 pub enum Direction {
@@ -43,7 +45,7 @@ pub enum Run {
     Command(RunCommand),
 }
 
-// The layout struct that is ultimately used to build the layouts
+// The layout struct ultimately used to build the layouts.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq)]
 #[serde(crate = "self::serde")]
 pub struct Layout {
@@ -56,6 +58,7 @@ pub struct Layout {
     pub run: Option<Run>,
 }
 
+// The tab-layout struct used to specify each individual tab.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq)]
 #[serde(crate = "self::serde")]
 pub struct TabLayout {
@@ -66,8 +69,8 @@ pub struct TabLayout {
     pub run: Option<Run>,
 }
 
-// Main layout struct, that carries information based on
-// position of tabs
+// Main layout struct, that carries information based on position of tabs
+// in relation to the whole layout.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Eq)]
 #[serde(crate = "self::serde")]
 pub struct MainLayout {
@@ -205,7 +208,9 @@ impl Layout {
 
     // Split the layout into parts that can be reassebled per tab
     // returns the layout pre tab, the parts post tab and the tab layouts
-    pub fn split_main_and_tab_layout(&self) -> (Layout, Vec<Layout>, Vec<TabLayout>) {
+    pub fn split_main_and_tab_layout(
+        &self,
+    ) -> Result<(Layout, Vec<Layout>, Vec<TabLayout>), LayoutPartAndTabError> {
         let mut main_layout = self.clone();
         let mut pre_tab_layout = self.clone();
         let mut post_tab_layout = vec![];
@@ -220,23 +225,21 @@ impl Layout {
             post_tab = true;
         }
 
+        if !main_layout.tabs.is_empty() && !main_layout.parts.is_empty() {
+            return Err(LayoutPartAndTabError);
+        }
+
         for part in main_layout.parts.drain(..) {
             let (curr_pre_layout, mut curr_post_layout, mut curr_tabs) =
-                part.split_main_and_tab_layout();
+                part.split_main_and_tab_layout()?;
 
             // Leaf
             if !post_tab && part.tabs.is_empty() {
                 pre_tab_layout.parts.push(curr_pre_layout);
             }
 
-            // Todo: Convert into actual Error, or use the future logging system.
             if !part.tabs.is_empty() && !part.parts.is_empty() {
-                panic!("Tabs and Parts need to be specified separately.");
-            }
-
-            // Todo: Convert into actual Error, or use the future logging system.
-            if (!part.tabs.is_empty() || !curr_tabs.is_empty()) && post_tab {
-                panic!("Only one tab section should be specified.");
+                return Err(LayoutPartAndTabError);
             }
 
             // Node
@@ -259,7 +262,7 @@ impl Layout {
                 }
             }
         }
-        (pre_tab_layout, post_tab_layout, tabs)
+        Ok((pre_tab_layout, post_tab_layout, tabs))
     }
 
     pub fn merge_tab_layout(&mut self, tab: TabLayout) {
@@ -271,33 +274,31 @@ impl Layout {
     }
 
     pub fn construct_full_layout(&self, tab_layout: Option<TabLayout>) -> Self {
+        // The `split_main_and_tab_layout()` error should have returned
+        // already from deserialisation, so we can assume it is `Ok()`.
+        let (mut pre_tab_layout, post_tab_layout, _) = self.split_main_and_tab_layout().unwrap();
         if let Some(tab_layout) = tab_layout {
-            let (mut pre_tab_layout, post_tab_layout, _) = self.split_main_and_tab_layout();
             pre_tab_layout.merge_tab_layout(tab_layout);
-            pre_tab_layout.merge_layout_parts(post_tab_layout);
-            pre_tab_layout
         } else {
-            let (mut pre_tab_layout, post_tab_layout, _) = self.split_main_and_tab_layout();
             let default_tab_layout = TabLayout::default();
             pre_tab_layout.merge_tab_layout(default_tab_layout);
-            pre_tab_layout.merge_layout_parts(post_tab_layout);
-            pre_tab_layout
         }
+        pre_tab_layout.merge_layout_parts(post_tab_layout);
+        pre_tab_layout
     }
 
-    pub fn construct_main_layout(&self) -> MainLayout {
-        let (pre_tab, post_tab, tabs) = self.split_main_and_tab_layout();
+    pub fn construct_main_layout(&self) -> Result<MainLayout, ConfigError> {
+        let (pre_tab, post_tab, tabs) = self.split_main_and_tab_layout()?;
 
-        // Todo: A proper LayoutError
         if tabs.is_empty() {
-            panic!("The layout file should have a [`tabs`] section specified");
+            return Err(ConfigError::Layout(LayoutMissingTabSectionError));
         }
 
-        MainLayout {
+        Ok(MainLayout {
             pre_tab,
             post_tab,
             tabs,
-        }
+        })
     }
 
     fn from_vec_tab_layout(tab_layout: Vec<TabLayout>) -> Vec<Self> {
diff --git a/zellij-utils/src/input/unit/fixtures/layouts/multiple-tabs-should-panic.yaml b/zellij-utils/src/input/unit/fixtures/layouts/multiple-tabs-should-not-error.yaml
index 653787591..653787591 100644
--- a/zellij-utils/src/input/unit/fixtures/layouts/multiple-tabs-should-panic.yaml
+++ b/zellij-utils/src/input/unit/fixtures/layouts/multiple-tabs-should-not-error.yaml
diff --git a/zellij-utils/src/input/unit/fixtures/layouts/no-tabs-should-panic.yaml b/zellij-utils/src/input/unit/fixtures/layouts/no-tabs-should-error.yaml
index a67b0ff95..a67b0ff95 100644
--- a/zellij-utils/src/input/unit/fixtures/layouts/no-tabs-should-panic.yaml
+++ b/zellij-utils/src/input/unit/fixtures/layouts/no-tabs-should-error.yaml
diff --git a/zellij-utils/src/input/unit/fixtures/layouts/tabs-and-parts-together-should-error.yaml b/zellij-utils/src/input/unit/fixtures/layouts/tabs-and-parts-together-should-error.yaml
new file mode 100644
index 000000000..e7223602d
--- /dev/null
+++ b/zellij-utils/src/input/unit/fixtures/layouts/tabs-and-parts-together-should-error.yaml
@@ -0,0 +1,17 @@
+---
+direction: Horizontal
+parts:
+  - direction: Horizontal
+    tabs:
+      - direction: Vertical
+        parts:
+          - direction: Horizontal
+            split_size:
+              Percent: 50
+    parts:
+      - direction: Vertical
+        split_size:
+          Percent: 50
+      - direction: Vertical
+        split_size:
+          Percent: 50
diff --git a/zellij-utils/src/input/unit/fixtures/layouts/tabs-and-parts-together-should-panic.yaml b/zellij-utils/src/input/unit/fixtures/layouts/tabs-and-parts-together-should-panic.yaml
deleted file mode 100644
index 1ef5a05ee..000000000
--- a/zellij-utils/src/input/unit/fixtures/layouts/tabs-and-parts-together-should-panic.yaml
+++ /dev/null
@@ -1,25 +0,0 @@
----
-direction: Horizontal
-parts:
-  - direction: Horizontal
-    tabs:
-      - direction: Vertical
-        parts:
-          - direction: Horizontal
-            split_size:
-              Percent: 50
-          - direction: Horizontal
-            parts:
-              - direction: Vertical
-                split_size:
-                  Percent: 50
-              - direction: Vertical
-                split_size:
-                  Percent: 50
-        tabs:
-          - direction: Vertical
-            split_size:
-              Percent: 50
-          - direction: Vertical
-            split_size:
-              Percent: 50
diff --git a/zellij-utils/src/input/unit/fixtures/layouts/three-tabs-merged-correctly.yaml b/zellij-utils/src/input/unit/fixtures/layouts/three-tabs-merged-correctly.yaml
new file mode 100644
index 000000000..96e1524d5
--- /dev/null
+++ b/zellij-utils/src/input/unit/fixtures/layouts/three-tabs-merged-correctly.yaml
@@ -0,0 +1,25 @@
+---
+direction: Vertical
+parts:
+  - direction: Horizontal
+    tabs:
+      - direction: Horizontal
+        split_size:
+          Percent: 50
+      - direction: Horizontal
+        split_size:
+          Percent: 50
+        parts:
+          - direction: Horizontal
+            split_size:
+              Percent: 50
+          - direction: Horizontal
+      - direction: Vertical
+        split_size:
+          Percent: 50
+        parts:
+          - direction: Vertical
+            split_size:
+              Percent: 50
+          - direction: Horizontal
+  - direction: Horizontal
diff --git a/zellij-utils/src/input/unit/layout_test.rs b/zellij-utils/src/input/unit/layout_test.rs
index 5d9fda35a..1a90c1ff4 100644
--- a/zellij-utils/src/input/unit/layout_test.rs
+++ b/zellij-utils/src/input/unit/layout_test.rs
@@ -23,7 +23,7 @@ fn default_layout_is_ok() {
 fn default_layout_has_one_tab() {
     let path = default_layout_dir("default.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     assert_eq!(main_layout.tabs.len(), 1);
 }
 
@@ -31,7 +31,7 @@ fn default_layout_has_one_tab() {
 fn default_layout_has_one_pre_tab() {
     let path = default_layout_dir("default.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     assert_eq!(main_layout.pre_tab.parts.len(), 1);
 }
 
@@ -39,7 +39,7 @@ fn default_layout_has_one_pre_tab() {
 fn default_layout_has_one_post_tab() {
     let path = default_layout_dir("default.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     assert_eq!(main_layout.post_tab.len(), 1);
 }
 
@@ -47,7 +47,7 @@ fn default_layout_has_one_post_tab() {
 fn default_layout_merged_correctly() {
     let path = default_layout_dir("default.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     let tab_layout = main_layout.construct_tab_layout(Some(main_layout.tabs[0].clone()));
     let merged_layout = Layout {
         direction: Direction::Horizontal,
@@ -85,7 +85,7 @@ fn default_layout_merged_correctly() {
 fn default_layout_new_tab_correct() {
     let path = default_layout_dir("default.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     let tab_layout = main_layout.construct_tab_layout(None);
     let merged_layout = Layout {
         direction: Direction::Horizontal,
@@ -137,7 +137,7 @@ fn default_disable_status_layout_is_ok() {
 fn default_disable_status_layout_has_one_tab() {
     let path = default_layout_dir("disable-status-bar.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     assert_eq!(main_layout.tabs.len(), 1);
 }
 
@@ -145,7 +145,7 @@ fn default_disable_status_layout_has_one_tab() {
 fn default_disable_status_layout_has_one_pre_tab() {
     let path = default_layout_dir("disable-status-bar.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     assert_eq!(main_layout.pre_tab.parts.len(), 1);
 }
 
@@ -153,7 +153,7 @@ fn default_disable_status_layout_has_one_pre_tab() {
 fn default_disable_status_layout_has_no_post_tab() {
     let path = default_layout_dir("disable-status-bar.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     assert!(main_layout.post_tab.is_empty());
 }
 
@@ -168,7 +168,7 @@ fn three_panes_with_tab_is_ok() {
 fn three_panes_with_tab_has_one_tab() {
     let path = layout_test_dir("three-panes-with-tab.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout().unwrap();
     assert_eq!(main_layout.tabs.len(), 1);
 }
 
@@ -176,7 +176,7 @@ fn three_panes_with_tab_has_one_tab() {
 fn three_panes_with_tab_no_post_tab() {
     let path = layout_test_dir("three-panes-with-tab.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout().unwrap();
     assert!(main_layout.post_tab.is_empty());
 }
 
@@ -184,7 +184,7 @@ fn three_panes_with_tab_no_post_tab() {
 fn three_panes_with_tab_no_pre_tab() {
     let path = layout_test_dir("three-panes-with-tab.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout().unwrap();
     assert!(main_layout.pre_tab.parts.is_empty());
 }
 
@@ -192,7 +192,7 @@ fn three_panes_with_tab_no_pre_tab() {
 fn three_panes_with_tab_merged_correctly() {
     let path = layout_test_dir("three-panes-with-tab.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     let tab_layout = main_layout.construct_tab_layout(Some(main_layout.tabs[0].clone()));
     let merged_layout = Layout {
         direction: Direction::Horizontal,
@@ -244,7 +244,7 @@ fn three_panes_with_tab_merged_correctly() {
 fn three_panes_with_tab_new_tab_is_correct() {
     let path = layout_test_dir("three-panes-with-tab.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     let tab_layout = main_layout.construct_tab_layout(None);
     let merged_layout = Layout {
         direction: Direction::Horizontal,
@@ -273,7 +273,7 @@ fn three_panes_with_tab_and_default_plugins_is_ok() {
 fn three_panes_with_tab_and_default_plugins_has_one_tab() {
     let path = layout_test_dir("three-panes-with-tab-and-default-plugins.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout().unwrap();
     assert_eq!(main_layout.tabs.len(), 1);
 }
 
@@ -281,7 +281,7 @@ fn three_panes_with_tab_and_default_plugins_has_one_tab() {
 fn three_panes_with_tab_and_default_plugins_one_post_tab() {
     let path = layout_test_dir("three-panes-with-tab-and-default-plugins.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout().unwrap();
     assert_eq!(main_layout.post_tab.len(), 1);
 }
 
@@ -289,7 +289,7 @@ fn three_panes_with_tab_and_default_plugins_one_post_tab() {
 fn three_panes_with_tab_and_default_plugins_has_pre_tab() {
     let path = layout_test_dir("three-panes-with-tab-and-default-plugins.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout().unwrap();
     assert!(!main_layout.pre_tab.parts.is_empty());
 }
 
@@ -297,7 +297,7 @@ fn three_panes_with_tab_and_default_plugins_has_pre_tab() {
 fn three_panes_with_tab_and_default_plugins_merged_correctly() {
     let path = layout_test_dir("three-panes-with-tab-and-default-plugins.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     let tab_layout = main_layout.construct_tab_layout(Some(main_layout.tabs[0].clone()));
     let merged_layout = Layout {
         direction: Direction::Horizontal,
@@ -365,7 +365,7 @@ fn three_panes_with_tab_and_default_plugins_merged_correctly() {
 fn three_panes_with_tab_and_default_plugins_new_tab_is_correct() {
     let path = layout_test_dir("three-panes-with-tab-and-default-plugins.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     let tab_layout = main_layout.construct_tab_layout(None);
     let merged_layout = Layout {
         direction: Direction::Horizontal,
@@ -410,7 +410,7 @@ fn deeply_nested_tab_is_ok() {
 fn deeply_nested_tab_has_one_tab() {
     let path = layout_test_dir("deeply-nested-tab-layout.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout().unwrap();
     assert_eq!(main_layout.tabs.len(), 1);
 }
 
@@ -418,7 +418,7 @@ fn deeply_nested_tab_has_one_tab() {
 fn deeply_nested_tab_three_post_tab() {
     let path = layout_test_dir("deeply-nested-tab-layout.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout().unwrap();
     assert_eq!(main_layout.post_tab.len(), 3);
 }
 
@@ -426,7 +426,7 @@ fn deeply_nested_tab_three_post_tab() {
 fn deeply_nested_tab_has_many_pre_tab() {
     let path = layout_test_dir("deeply-nested-tab-layout.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout().unwrap();
     assert!(!main_layout.pre_tab.parts.is_empty());
 }
 
@@ -434,7 +434,7 @@ fn deeply_nested_tab_has_many_pre_tab() {
 fn deeply_nested_tab_merged_correctly() {
     let path = layout_test_dir("deeply-nested-tab-layout.yaml".into());
     let layout = Layout::new(&path);
-    let main_layout = layout.as_ref().unwrap().construct_main_layout();
+    let main_layout = layout.as_ref().unwrap().construct_main_layout().unwrap();
     let tab_layout = main_layout.construct_tab_layout(Some(main_layout.tabs[0].clone()));
     let merged_layout = Layout {
         direction: Direction::Horizontal,
@@ -519,17 +519,172 @@ fn deeply_nested_tab_merged_correctly() {
 }
 
 #[test]
-#[should_panic]
-// TODO Make error out of this
-fn no_tabs_specified_should_panic() {
-    let path = layout_test_dir("no-tabs-should-panic.yaml".into());
+fn no_tabs_specified_should_err() {
+    let path = layout_test_dir("no-tabs-should-error.yaml".into());
     let layout = Layout::new(&path);
-    let _main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout();
+    assert!(main_layout.is_err());
 }
 
 #[test]
-fn multiple_tabs_specified_should_not_panic() {
-    let path = layout_test_dir("multiple-tabs-should-panic.yaml".into());
+fn tabs_and_parts_specified_together_should_should_err() {
+    let path = layout_test_dir("tabs-and-parts-together-should-error.yaml".into());
     let layout = Layout::new(&path);
-    let _main_layout = layout.unwrap().construct_main_layout();
+    let main_layout = layout.unwrap().construct_main_layout();
+    assert!(main_layout.is_err());
+}
+
+#[test]
+fn multiple_tabs_specified_should_not_err() {
+    let path = layout_test_dir("multiple-tabs-should-not-error.yaml".into());
+    let layout = Layout::new(&path);
+    let main_layout = layout.unwrap().construct_main_layout();
+    assert!(main_layout.is_ok())
+}