refactor: break out into functions and draft tests

Signed-off-by: Jesse Simpson <jesse.simpson36@gmail.com>

pkg/engine/engine.go

@@ -360,12 +360,56 @@ func parseTemplateExecErrorString(s string) (TraceableError, bool) {
 
 	// Special case: "template: no template %q associated with template %q"
 	// Matches https://cs.opensource.google/go/go/+/refs/tags/go1.23.6:src/text/template/exec.go;l=191
-	if strings.HasPrefix(remainder, "no template ") {
-		return TraceableError{message: s}, true
+	traceableError, done := parseTemplateNoTemplateError(s, remainder)
+	if done {
+		return traceableError, done
 	}
 
 	// Executing form: "<templateName>: executing \"<funcName>\" at <<location>>: <errMsg>[ template:...]"
 	// Matches https://cs.opensource.google/go/go/+/refs/tags/go1.23.6:src/text/template/exec.go;l=141
+	traceableError, done = parseTemplateExecutingAtErrorType(remainder)
+	if done {
+		return traceableError, done
+	}
+
+	// Simple form: "<templateName>: <errMsg>"
+	// Use LastIndex to avoid splitting colons within line:col info.
+	// Matches https://cs.opensource.google/go/go/+/refs/tags/go1.23.6:src/text/template/exec.go;l=138
+	traceableError, done = parseTemplateSimpleErrorString(remainder)
+	if done {
+		return traceableError, done
+	}
+
+	return TraceableError{}, false
+}
+
+// Special case: "template: no template %q associated with template %q"
+// Matches https://cs.opensource.google/go/go/+/refs/tags/go1.23.6:src/text/template/exec.go;l=191
+func parseTemplateNoTemplateError(s string, remainder string) (TraceableError, bool) {
+	if strings.HasPrefix(remainder, "no template ") {
+		return TraceableError{message: s}, true
+	}
+	return TraceableError{}, false
+}
+
+// Simple form: "<templateName>: <errMsg>"
+// Use LastIndex to avoid splitting colons within line:col info.
+// Matches https://cs.opensource.google/go/go/+/refs/tags/go1.23.6:src/text/template/exec.go;l=138
+func parseTemplateSimpleErrorString(remainder string) (TraceableError, bool) {
+	if sep := strings.LastIndex(remainder, ": "); sep != -1 {
+		templateName := remainder[:sep]
+		errMsg := remainder[sep+2:]
+		if cut := strings.Index(errMsg, " template:"); cut != -1 {
+			errMsg = errMsg[:cut]
+		}
+		return TraceableError{location: templateName, message: errMsg}, true
+	}
+	return TraceableError{}, false
+}
+
+// Executing form: "<templateName>: executing \"<funcName>\" at <<location>>: <errMsg>[ template:...]"
+// Matches https://cs.opensource.google/go/go/+/refs/tags/go1.23.6:src/text/template/exec.go;l=141
+func parseTemplateExecutingAtErrorType(remainder string) (TraceableError, bool) {
 	if idx := strings.Index(remainder, ": executing "); idx != -1 {
 		templateName := remainder[:idx]
 		after := remainder[idx+len(": executing "):]
@@ -404,19 +448,6 @@ func parseTemplateExecErrorString(s string) (TraceableError, bool) {
 			executedFunction: "executing \"" + functionName + "\" at <" + locationName + ">:",
 		}, true
 	}
-
-	// Simple form: "<templateName>: <errMsg>"
-	// Use LastIndex to avoid splitting colons within line:col info.
-	// Matches https://cs.opensource.google/go/go/+/refs/tags/go1.23.6:src/text/template/exec.go;l=138
-	if sep := strings.LastIndex(remainder, ": "); sep != -1 {
-		templateName := remainder[:sep]
-		errMsg := remainder[sep+2:]
-		if cut := strings.Index(errMsg, " template:"); cut != -1 {
-			errMsg = errMsg[:cut]
-		}
-		return TraceableError{location: templateName, message: errMsg}, true
-	}
-
 	return TraceableError{}, false
 }
 

pkg/engine/engine_test.go

@@ -1428,3 +1428,50 @@ func TestRenderCustomTemplateFuncs(t *testing.T) {
 		t.Errorf("Expected %q, got %q", expected, rendered)
 	}
 }
+
+func TestTraceableError_SimpleForm(t *testing.T) {
+	testStrings := []string{
+		"function_not_found/templates/secret.yaml: error calling include",
+	}
+	for _, errString := range testStrings {
+		trace, done := parseTemplateSimpleErrorString(errString)
+		if !done {
+			t.Errorf("Expected parse to pass but did not")
+		}
+		if trace.message != "error calling include" {
+			t.Errorf("Expected %q, got %q", errString, trace.message)
+		}
+	}
+}
+func TestTraceableError_ExecutingForm(t *testing.T) {
+	testStrings := [][]string{
+		{"template: executing \"function_not_found/templates/secret.yaml\" at <include \"name\" .>: ", "function_not_found/templates/secret.yaml"},
+		{"template: executing \"name\" at <include \"common.names.get_name\" .>: ", "name"},
+	}
+	for _, errTuple := range testStrings {
+		errString := errTuple[0]
+		expectedLocation := errTuple[1]
+		trace, done := parseTemplateExecutingAtErrorType(errString)
+		if !done {
+			t.Errorf("Expected parse to pass but did not")
+		}
+		if trace.location != expectedLocation {
+			t.Errorf("Expected %q, got %q", expectedLocation, trace.location)
+		}
+	}
+}
+
+func TestTraceableError_NoTemplateForm(t *testing.T) {
+	testStrings := []string{
+		"no template \"common.names.get_name\" associated with template \"gotpl\"",
+	}
+	for _, errString := range testStrings {
+		trace, done := parseTemplateNoTemplateError(errString, "")
+		if !done {
+			t.Errorf("Expected parse to pass but did not")
+		}
+		if trace.message != errString {
+			t.Errorf("Expected %q, got %q", errString, trace.message)
+		}
+	}
+}