diff --git a/internal/processor/script-expr_test.go b/internal/processor/script-expr_test.go
index 8294741..8c9d482 100644
--- a/internal/processor/script-expr_test.go
+++ b/internal/processor/script-expr_test.go
@@ -4,9 +4,83 @@ import (
 	"testing"
 
 	"github.com/expr-lang/expr"
+	"github.com/jwetzell/showbridge-go/internal/config"
 	"github.com/jwetzell/showbridge-go/internal/processor"
 )
 
+func TestScriptExprFromRegistry(t *testing.T) {
+	registration, ok := processor.ProcessorRegistry["script.expr"]
+	if !ok {
+		t.Fatalf("script.expr processor not registered")
+	}
+
+	processorInstance, err := registration.New(config.ProcessorConfig{
+		Type: "script.expr",
+		Params: map[string]any{
+			"expression": "foo + bar",
+		},
+	})
+	if err != nil {
+		t.Fatalf("failed to create script.expr processor: %s", err)
+	}
+
+	if processorInstance.Type() != "script.expr" {
+		t.Fatalf("script.expr processor has wrong type: %s", processorInstance.Type())
+	}
+}
+
+func TestScriptExprNoProgram(t *testing.T) {
+	registration, ok := processor.ProcessorRegistry["script.expr"]
+	if !ok {
+		t.Fatalf("script.expr processor not registered")
+	}
+
+	_, err := registration.New(config.ProcessorConfig{
+		Type:   "script.expr",
+		Params: map[string]any{},
+	})
+
+	if err == nil {
+		t.Fatalf("script.expr processor should have thrown an error when creating")
+	}
+}
+
+func TestScriptExprBadConfigWrongExpressionType(t *testing.T) {
+	registration, ok := processor.ProcessorRegistry["script.expr"]
+	if !ok {
+		t.Fatalf("script.expr processor not registered")
+	}
+
+	_, err := registration.New(config.ProcessorConfig{
+		Type: "script.expr",
+		Params: map[string]any{
+			"expression": 12345,
+		},
+	})
+
+	if err == nil {
+		t.Fatalf("script.expr processor should have thrown an error when creating with non-string expression")
+	}
+}
+
+func TestScriptExprBadConfigNonCompilingExpression(t *testing.T) {
+	registration, ok := processor.ProcessorRegistry["script.expr"]
+	if !ok {
+		t.Fatalf("script.expr processor not registered")
+	}
+
+	_, err := registration.New(config.ProcessorConfig{
+		Type: "script.expr",
+		Params: map[string]any{
+			"expression": "foo + ",
+		},
+	})
+
+	if err == nil {
+		t.Fatalf("script.expr processor should have thrown an error when creating with non-compiling expression")
+	}
+}
+
 func TestGoodScriptExpr(t *testing.T) {
 	tests := []struct {
 		program  string
@@ -56,3 +130,42 @@ func TestGoodScriptExpr(t *testing.T) {
 		})
 	}
 }
+
+func TestBadScriptExpr(t *testing.T) {
+	tests := []struct {
+		program     string
+		name        string
+		payload     map[string]any
+		errorString string
+	}{
+		{
+			name:    "accessing missing field",
+			program: "foo + bar",
+			payload: map[string]any{
+				"foo": 1,
+			},
+			errorString: "invalid operation: int + <nil> (1:5)\n | foo + bar\n | ....^",
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			program, err := expr.Compile(test.program)
+			if err != nil {
+				t.Fatalf("script.expr failed to compile program: %s", err)
+			}
+
+			exprProcessor := &processor.ScriptExpr{Program: program}
+
+			got, err := exprProcessor.Process(t.Context(), test.payload)
+
+			if err == nil {
+				t.Fatalf("script.expr expected to fail but succeeded, got: %v", got)
+
+			}
+			if err.Error() != test.errorString {
+				t.Fatalf("script.expr got error '%s', expected '%s'", err.Error(), test.errorString)
+			}
+		})
+	}
+}