[Support] Unable to init GTK with unit tests

[shanmukhateja]

Description

I am trying to add unit tests to my project and my tests keep failing.

Code

#[cfg(test)]
mod tests {
    use gtk::Builder;
    use libmystudio::notebook::cache::NotebookTabCache;
    use tempfile::tempdir;

    use crate::ui::notebook::{
        editor::{get_editor_by_path, get_editor_instance},
        nbmain::{create_notebook_tab, get_notebook},
    };

    use super::set_text_on_editor;

    fn before_each() -> (Builder, tempfile::TempDir, std::path::PathBuf) {
        gtk_test::gtk::init().unwrap();

        // Load UI from glade file
        let glade_src = include_str!("../../../res/ui/main_window.glade");
        let builder: Builder = Builder::from_string(glade_src);

        // Init Notebook UI for testing
        crate::ui::notebook::init(&builder);

        // Create mock file 
        let root_dir = tempdir();
        assert!(root_dir.is_ok());
        let root_dir = root_dir.unwrap();

        let temp_file = root_dir.path().join("index.js");

        (builder, root_dir, temp_file)

    }

    #[test]
    fn get_editor_by_path_test() {
        // init Gtk
        let (builder, root_dir, temp_file) = before_each();
        
        // mock Notebook page
        let notebook = get_notebook().unwrap();
        let mock_editor = get_editor_instance();
        let tab_position = create_notebook_tab(notebook, mock_editor, "title", "icon_name");

        // mock Notebook cache entry
        let mock_cache = NotebookTabCache {
            file_path: temp_file.to_str().unwrap().into(),
            icon_name: "file".into(),
            position: tab_position,
        };
        NotebookTabCache::insert(mock_cache.clone());

        // Verify if editor is available
        let editor = get_editor_by_path(mock_cache.file_path);
        assert!(editor.is_some());
    }

    #[test]
    fn set_text_on_editor_test() {

        // Init
        let (_builder, _root_dir, temp_file_pathbuf) = before_each();
        let temp_file_str = temp_file_pathbuf.to_str().map(|f| f.to_string());

        let mock_editor = get_editor_instance();

        // all params are provided
        set_text_on_editor(Some(mock_editor), temp_file_str.clone(), Some("console.log(1);".into()));
        
        // editor is None
        // set_text_on_editor(None, temp_file_str, Some("console.log(1);".into()));

    }
}

Actual Output

➜  mystudio-ide git:(unit-tests) ✗ cargo test -p mystudio-ide --bin mystudio-ide
   Compiling mystudio-ide v0.1.3 (/home/suryateja/Projects/mystudio-ide/mystudio-ide)
warning: unused variable: `builder`
   --> mystudio-ide/src/ui/notebook/editor.rs:151:14
    |
151 |         let (builder, root_dir, temp_file) = before_each();
    |              ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_builder`
    |
    = note: `#[warn(unused_variables)]` on by default

warning: unused variable: `root_dir`
   --> mystudio-ide/src/ui/notebook/editor.rs:151:23
    |
151 |         let (builder, root_dir, temp_file) = before_each();
    |                       ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_root_dir`

warning: `mystudio-ide` (bin "mystudio-ide" test) generated 2 warnings
    Finished test [unoptimized + debuginfo] target(s) in 8.29s
     Running unittests src/main.rs (target/debug/deps/mystudio_ide-b03e5f831783b6a6)

running 3 tests
test ui::action_row::handler::tests::save_file_changes_test ... ok
test ui::notebook::editor::tests::get_editor_by_path_test ... FAILED
test ui::notebook::editor::tests::set_text_on_editor_test ... FAILED

failures:

---- ui::notebook::editor::tests::get_editor_by_path_test stdout ----
thread 'ui::notebook::editor::tests::get_editor_by_path_test' panicked at 'called `Result::unwrap()` on an `Err` value: BoolError { message: "Failed to acquire default main context", filename: "/home/suryateja/.cargo/registry/src/github.com-1ecc6299db9ec823/gtk-0.15.4/src/rt.rs", function: "gtk::rt", line: 129 }', mystudio-ide/src/ui/notebook/editor.rs:128:31
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

---- ui::notebook::editor::tests::set_text_on_editor_test stdout ----
thread 'ui::notebook::editor::tests::set_text_on_editor_test' panicked at 'called `Option::unwrap()` on a `None` value', mystudio-ide/src/ui/statusbar/line_indicator.rs:162:36


failures:
    ui::notebook::editor::tests::get_editor_by_path_test
    ui::notebook::editor::tests::set_text_on_editor_test

test result: FAILED. 1 passed; 2 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.15s

error: test failed, to rerun pass '-p mystudio-ide --bin mystudio-ide'

Please advise.