fix(tomcat): propagate os.Stat errors and always remove ROOT.xml on non-root context_path

- os.Stat unexpected errors (non-IsNotExist) now returned as failures instead
  of silently treating the context XML as already existing
- ROOT.xml removal now happens regardless of whether context XML was generated
  or already existed from external config, so non-root context_path always
  removes a stale ROOT.xml
- Unit test added (TDD) for external-config + non-root ROOT.xml removal

Author: stokpop

src/java/containers/tomcat.go

@@ -593,7 +593,11 @@ func (t *TomcatContainer) Finalize() error {
 			return fmt.Errorf("failed to create context directory: %w", err)
 		}
 
-		if _, statErr := os.Stat(contextXMLPath); os.IsNotExist(statErr) {
+		_, statErr := os.Stat(contextXMLPath)
+		if statErr != nil && !os.IsNotExist(statErr) {
+			return fmt.Errorf("failed to check context XML %s: %w", contextXMLName, statErr)
+		}
+		if os.IsNotExist(statErr) {
 			appContextXML := filepath.Join(buildDir, "META-INF", "context.xml")
 			var contextContent string
 
@@ -616,16 +620,15 @@ func (t *TomcatContainer) Finalize() error {
 			if err := os.WriteFile(contextXMLPath, []byte(contextContent), 0644); err != nil {
 				return fmt.Errorf("failed to write %s: %w", contextXMLName, err)
 			}
-
-			if contextXMLName != "ROOT.xml" {
-				rootXMLPath := filepath.Join(t.tomcatDir(), "conf", "Catalina", "localhost", "ROOT.xml")
-				if err := os.Remove(rootXMLPath); err != nil && !os.IsNotExist(err) {
-					return fmt.Errorf("failed to remove ROOT.xml: %w", err)
-				}
-			}
 		} else {
 			t.context.Log.Info("Context XML %s already exists (e.g. from external config), skipping generation", contextXMLName)
 		}
+		if contextXMLName != "ROOT.xml" {
+			rootXMLPath := filepath.Join(t.tomcatDir(), "conf", "Catalina", "localhost", "ROOT.xml")
+			if err := os.Remove(rootXMLPath); err != nil && !os.IsNotExist(err) {
+				return fmt.Errorf("failed to remove ROOT.xml: %w", err)
+			}
+		}
 	} else {
 		warMatches, err := filepath.Glob(filepath.Join(buildDir, "*.war"))
 		if err == nil && len(warMatches) == 1 {
@@ -637,21 +640,24 @@ func (t *TomcatContainer) Finalize() error {
 				return fmt.Errorf("failed to create context directory: %w", err)
 			}
 
-			if _, statErr := os.Stat(contextXMLPath); os.IsNotExist(statErr) {
+			_, statErr := os.Stat(contextXMLPath)
+			if statErr != nil && !os.IsNotExist(statErr) {
+				return fmt.Errorf("failed to check context XML %s: %w", contextXMLName, statErr)
+			}
+			if os.IsNotExist(statErr) {
 				if err := os.WriteFile(contextXMLPath, []byte(contextContent), 0644); err != nil {
 					return fmt.Errorf("failed to write %s: %w", contextXMLName, err)
 				}
-
-				if contextXMLName != "ROOT.xml" {
-					rootXMLPath := filepath.Join(t.tomcatDir(), "conf", "Catalina", "localhost", "ROOT.xml")
-					if err := os.Remove(rootXMLPath); err != nil && !os.IsNotExist(err) {
-						return fmt.Errorf("failed to remove ROOT.xml: %w", err)
-					}
-				}
 				t.context.Log.Info("Created %s with docBase pointing to %s", contextXMLName, warFilename)
 			} else {
 				t.context.Log.Info("Context XML %s already exists (e.g. from external config), skipping generation", contextXMLName)
 			}
+			if contextXMLName != "ROOT.xml" {
+				rootXMLPath := filepath.Join(t.tomcatDir(), "conf", "Catalina", "localhost", "ROOT.xml")
+				if err := os.Remove(rootXMLPath); err != nil && !os.IsNotExist(err) {
+					return fmt.Errorf("failed to remove ROOT.xml: %w", err)
+				}
+			}
 		} else if len(warMatches) > 1 {
 			t.context.Log.Warning("Multiple WAR files found in build directory; context_path not applied")
 		}

src/java/containers/tomcat_test.go

@@ -279,6 +279,28 @@ var _ = Describe("Tomcat Container", func() {
 			Expect(string(content)).To(Equal(preExistingContent))
 		})
 
+		It("removes ROOT.xml even when non-root context XML already exists (external config)", func() {
+			os.Setenv("JBP_CONFIG_TOMCAT", `{tomcat: {context_path: /my/path}}`)
+			defer os.Unsetenv("JBP_CONFIG_TOMCAT")
+
+			tomcatDir := filepath.Join(depsDir, "0", "tomcat")
+			contextDir := filepath.Join(tomcatDir, "conf", "Catalina", "localhost")
+			Expect(os.MkdirAll(contextDir, 0755)).To(Succeed())
+			externalContent := "<Context docBase=\"/external/path\"/>"
+			contextXML := filepath.Join(contextDir, "my#path.xml")
+			Expect(os.WriteFile(contextXML, []byte(externalContent), 0644)).To(Succeed())
+			rootXML := filepath.Join(contextDir, "ROOT.xml")
+			Expect(os.WriteFile(rootXML, []byte("<Context/>"), 0644)).To(Succeed())
+
+			err := container.Finalize()
+			Expect(err).NotTo(HaveOccurred())
+
+			content, readErr := os.ReadFile(contextXML)
+			Expect(readErr).NotTo(HaveOccurred())
+			Expect(string(content)).To(Equal(externalContent))
+			Expect(rootXML).NotTo(BeAnExistingFile())
+		})
+
 		Context("with packaged WAR (no WEB-INF)", func() {
 			BeforeEach(func() {
 				Expect(os.RemoveAll(filepath.Join(buildDir, "WEB-INF"))).To(Succeed())