Make ragg optional in tests (#951)

Author: lionel-

crates/amalthea/src/fixtures/dummy_frontend.rs

@@ -464,6 +464,31 @@ impl DummyFrontend {
             eprintln!("---");
         }
     }
+
+    pub fn is_installed(&self, package: &str) -> bool {
+        let code = format!(".ps.is_installed('{package}')");
+        self.send_execute_request(&code, ExecuteRequestOptions::default());
+        self.recv_iopub_busy();
+
+        let input = self.recv_iopub_execute_input();
+        assert_eq!(input.code, code);
+
+        let result = self.recv_iopub_execute_result();
+
+        let out = if result == "[1] TRUE" {
+            true
+        } else if result == "[1] FALSE" {
+            false
+        } else {
+            panic!("Expected `TRUE` or `FALSE`, got '{result}'.");
+        };
+
+        self.recv_iopub_idle();
+
+        assert_eq!(self.recv_shell_execute_reply(), input.execution_count);
+
+        out
+    }
 }
 
 impl Default for ExecuteRequestOptions {

crates/ark/tests/plots.rs

@@ -170,7 +170,12 @@ fn test_graphics_device_initialization() {
 fn test_ragg_is_used_by_default() {
     let frontend = DummyArkFrontend::lock();
 
-    // We install ragg on CI and expect developers to have it locally
+    if !frontend.is_installed("ragg") {
+        report_skipped("test_ragg_is_used_by_default", "ragg");
+        return;
+    }
+
+    // We install ragg on CI, but developers may not have it locally
     let code = ".ps.internal(use_ragg())";
     frontend.send_execute_request(code, ExecuteRequestOptions::default());
     frontend.recv_iopub_busy();
@@ -186,6 +191,11 @@ fn test_inability_to_load_ragg_falls_back_to_base_graphics() {
     // https://github.com/posit-dev/ark/issues/917
     let frontend = DummyArkFrontend::lock();
 
+    if !frontend.is_installed("ragg") {
+        report_skipped("test_ragg_is_used_by_default", "ragg");
+        return;
+    }
+
     // Mock `loadNamespace()` with a version that will fail on ragg
     let code = r#"
 oldLoadNamespace <- base::loadNamespace
@@ -228,3 +238,7 @@ lockBinding("loadNamespace", .BaseNamespaceEnv)
     frontend.recv_iopub_idle();
     assert_eq!(frontend.recv_shell_execute_reply(), input.execution_count);
 }
+
+fn report_skipped(f: &str, pkg: &str) {
+    println!("Skipping `{f}()`. {pkg} is not installed.");
+}

crates/ark/tests/rstudioapi.rs

@@ -77,28 +77,7 @@ fn set_var(key: &str, value: &str, frontend: &DummyArkFrontend) {
 }
 
 fn has_rstudioapi(frontend: &DummyArkFrontend) -> bool {
-    let code = ".ps.is_installed('rstudioapi')";
-    frontend.send_execute_request(code, ExecuteRequestOptions::default());
-    frontend.recv_iopub_busy();
-
-    let input = frontend.recv_iopub_execute_input();
-    assert_eq!(input.code, code);
-
-    let result = frontend.recv_iopub_execute_result();
-
-    let out = if result == "[1] TRUE" {
-        true
-    } else if result == "[1] FALSE" {
-        false
-    } else {
-        panic!("Expected `TRUE` or `FALSE`, got '{result}'.");
-    };
-
-    frontend.recv_iopub_idle();
-
-    assert_eq!(frontend.recv_shell_execute_reply(), input.execution_count);
-
-    out
+    frontend.is_installed("rstudioapi")
 }
 
 fn report_skipped(f: &str) {