Move panicx.Location into its own package.

engine/controller/aggregate/controller.go

@@ -10,6 +10,7 @@ import (
 	"github.com/dogmatiq/testkit/engine/envelope"
 	"github.com/dogmatiq/testkit/engine/fact"
 	"github.com/dogmatiq/testkit/engine/panicx"
+	"github.com/dogmatiq/testkit/internal/location"
 )
 
 // Controller is an implementation of engine.Controller for
@@ -65,7 +66,7 @@ func (c *Controller) Handle(
 			Implementation: c.Config.Handler(),
 			Message:        env.Message,
 			Description:    fmt.Sprintf("routed a command of type %T to an empty instance ID", env.Message),
-			Location:       panicx.LocationOfMethod(c.Config.Handler(), "RouteCommandToInstance"),
+			Location:       location.OfMethod(c.Config.Handler(), "RouteCommandToInstance"),
 		})
 	}
 
@@ -79,7 +80,7 @@ func (c *Controller) Handle(
 			Implementation: c.Config.Handler(),
 			Message:        env.Message,
 			Description:    "returned a nil AggregateRoot",
-			Location:       panicx.LocationOfMethod(c.Config.Handler(), "New"),
+			Location:       location.OfMethod(c.Config.Handler(), "New"),
 		})
 	}
 

engine/controller/aggregate/scope.go

@@ -9,6 +9,7 @@ import (
 	"github.com/dogmatiq/testkit/engine/envelope"
 	"github.com/dogmatiq/testkit/engine/fact"
 	"github.com/dogmatiq/testkit/engine/panicx"
+	"github.com/dogmatiq/testkit/internal/location"
 )
 
 // scope is an implementation of dogma.AggregateCommandScope.
@@ -53,7 +54,7 @@ func (s *scope) RecordEvent(m dogma.Message) {
 			Implementation: s.config.Handler(),
 			Message:        s.command.Message,
 			Description:    fmt.Sprintf("recorded an event of type %T, which is not produced by this handler", m),
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 
@@ -65,7 +66,7 @@ func (s *scope) RecordEvent(m dogma.Message) {
 			Implementation: s.config.Handler(),
 			Message:        s.command.Message,
 			Description:    fmt.Sprintf("recorded an invalid %T event: %s", m, err),
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 

engine/controller/integration/scope.go

@@ -9,6 +9,7 @@ import (
 	"github.com/dogmatiq/testkit/engine/envelope"
 	"github.com/dogmatiq/testkit/engine/fact"
 	"github.com/dogmatiq/testkit/engine/panicx"
+	"github.com/dogmatiq/testkit/internal/location"
 )
 
 // scope is an implementation of dogma.IntegrationCommandScope.
@@ -30,7 +31,7 @@ func (s *scope) RecordEvent(m dogma.Message) {
 			Implementation: s.config.Handler(),
 			Message:        s.command.Message,
 			Description:    fmt.Sprintf("recorded an event of type %T, which is not produced by this handler", m),
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 
@@ -42,7 +43,7 @@ func (s *scope) RecordEvent(m dogma.Message) {
 			Implementation: s.config.Handler(),
 			Message:        s.command.Message,
 			Description:    fmt.Sprintf("recorded an invalid %T event: %s", m, err),
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 

engine/controller/process/controller.go

@@ -12,6 +12,7 @@ import (
 	"github.com/dogmatiq/testkit/engine/envelope"
 	"github.com/dogmatiq/testkit/engine/fact"
 	"github.com/dogmatiq/testkit/engine/panicx"
+	"github.com/dogmatiq/testkit/internal/location"
 )
 
 // Controller is an implementation of engine.Controller for
@@ -114,7 +115,7 @@ func (c *Controller) Handle(
 				Implementation: c.Config.Handler(),
 				Message:        env.Message,
 				Description:    "returned a nil ProcessRoot",
-				Location:       panicx.LocationOfMethod(c.Config.Handler(), "New"),
+				Location:       location.OfMethod(c.Config.Handler(), "New"),
 			})
 		}
 	}
@@ -203,7 +204,7 @@ func (c *Controller) routeEvent(
 				Implementation: handler,
 				Message:        env.Message,
 				Description:    fmt.Sprintf("routed an event of type %T to an empty instance ID", env.Message),
-				Location:       panicx.LocationOfMethod(c.Config.Handler(), "RouteEventToInstance"),
+				Location:       location.OfMethod(c.Config.Handler(), "RouteEventToInstance"),
 			})
 		}
 

engine/controller/process/scope.go

@@ -10,6 +10,7 @@ import (
 	"github.com/dogmatiq/testkit/engine/envelope"
 	"github.com/dogmatiq/testkit/engine/fact"
 	"github.com/dogmatiq/testkit/engine/panicx"
+	"github.com/dogmatiq/testkit/internal/location"
 )
 
 // scope is an implementation of dogma.ProcessEventScope and
@@ -63,7 +64,7 @@ func (s *scope) End() {
 			Message:        s.env.Message,
 			Implementation: s.config.Handler(),
 			Description:    "ended a process instance that has not begun",
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 
@@ -88,7 +89,7 @@ func (s *scope) Root() dogma.ProcessRoot {
 			Message:        s.env.Message,
 			Implementation: s.config.Handler(),
 			Description:    "accessed the root of a process instance that has not begun",
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 
@@ -104,7 +105,7 @@ func (s *scope) ExecuteCommand(m dogma.Message) {
 			Implementation: s.config.Handler(),
 			Message:        s.env.Message,
 			Description:    fmt.Sprintf("executed a command of type %T, which is not produced by this handler", m),
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 
@@ -116,7 +117,7 @@ func (s *scope) ExecuteCommand(m dogma.Message) {
 			Message:        s.env.Message,
 			Implementation: s.config.Handler(),
 			Description:    fmt.Sprintf("executed an invalid %T command: %s", m, err),
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 
@@ -128,7 +129,7 @@ func (s *scope) ExecuteCommand(m dogma.Message) {
 			Message:        s.env.Message,
 			Implementation: s.config.Handler(),
 			Description:    fmt.Sprintf("executed a command of type %T on a process instance that has not begun", m),
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 
@@ -167,7 +168,7 @@ func (s *scope) ScheduleTimeout(m dogma.Message, t time.Time) {
 			Implementation: s.config.Handler(),
 			Message:        s.env.Message,
 			Description:    fmt.Sprintf("scheduled a timeout of type %T, which is not produced by this handler", m),
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 
@@ -179,7 +180,7 @@ func (s *scope) ScheduleTimeout(m dogma.Message, t time.Time) {
 			Message:        s.env.Message,
 			Implementation: s.config.Handler(),
 			Description:    fmt.Sprintf("scheduled an invalid %T timeout: %s", m, err),
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 
@@ -191,7 +192,7 @@ func (s *scope) ScheduleTimeout(m dogma.Message, t time.Time) {
 			Message:        s.env.Message,
 			Implementation: s.config.Handler(),
 			Description:    fmt.Sprintf("scheduled a timeout of type %T on a process instance that has not begun", m),
-			Location:       panicx.LocationOfCall(),
+			Location:       location.OfCall(),
 		})
 	}
 

engine/panicx/linenumber_test.go

@@ -10,7 +10,7 @@ package panicx_test
 
 import (
 	"github.com/dogmatiq/dogma"
-	. "github.com/dogmatiq/testkit/engine/panicx"
+	// import padding
 	// import padding
 	// import padding
 	// import padding
@@ -47,11 +47,4 @@ import (
 	// import padding
 )
 
-func doNothing()                     {}
-func panicWithUnexpectedMessage()    { panic(dogma.UnexpectedMessage) }
-func locationOfCallLayer1() Location { return LocationOfCall() }
-func locationOfCallLayer2() Location { return locationOfCallLayer1() }
-
-type locationOfMethodT struct{}
-
-func (locationOfMethodT) Method() {}
+func doPanic() { panic(dogma.UnexpectedMessage) }

engine/panicx/unexpectedbehavior.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/dogmatiq/configkit"
 	"github.com/dogmatiq/dogma"
+	"github.com/dogmatiq/testkit/internal/location"
 )
 
 // UnexpectedBehavior is a panic value that occurs when a handler exhibits some
@@ -33,7 +34,7 @@ type UnexpectedBehavior struct {
 
 	// Location is the engine's best attempt at pinpointing the location of the
 	// unexpected behavior.
-	Location Location
+	Location location.Location
 }
 
 func (x UnexpectedBehavior) String() string {

engine/panicx/unexpectedmessage.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/dogmatiq/configkit"
 	"github.com/dogmatiq/dogma"
+	"github.com/dogmatiq/testkit/internal/location"
 )
 
 // UnexpectedMessage is a panic value that provides more context when a handler
@@ -28,7 +29,7 @@ type UnexpectedMessage struct {
 	Message dogma.Message
 
 	// PanicLocation is the location of the function that panicked, if known.
-	PanicLocation Location
+	PanicLocation location.Location
 }
 
 func (x UnexpectedMessage) String() string {
@@ -66,7 +67,7 @@ func EnrichUnexpectedMessage(
 				Method:         method,
 				Implementation: impl,
 				Message:        m,
-				PanicLocation:  LocationOfPanic(),
+				PanicLocation:  location.OfPanic(),
 			}
 		}
 

engine/panicx/unexpectedmessage_test.go

@@ -96,7 +96,7 @@ var _ = Describe("func EnrichUnexpectedMessage()", func() {
 				"<method>",
 				config.Handler(),
 				MessageA1,
-				panicWithUnexpectedMessage,
+				doPanic,
 			)
 		}).To(PanicWith(
 			MatchAllFields(
@@ -108,9 +108,9 @@ var _ = Describe("func EnrichUnexpectedMessage()", func() {
 					"Message":        Equal(MessageA1),
 					"PanicLocation": MatchAllFields(
 						Fields{
-							"Func": Equal("github.com/dogmatiq/testkit/engine/panicx_test.panicWithUnexpectedMessage"),
+							"Func": Equal("github.com/dogmatiq/testkit/engine/panicx_test.doPanic"),
 							"File": HaveSuffix("/engine/panicx/linenumber_test.go"),
-							"Line": Equal(51),
+							"Line": Equal(50),
 						},
 					),
 				},

internal/location/doc.go

@@ -0,0 +1,3 @@
+// Package location contains utilities for obtaining the function, file and line
+// number of various Go types and values.
+package location

internal/location/ginkgo_test.go

@@ -0,0 +1,15 @@
+package location_test
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/onsi/ginkgo"
+	"github.com/onsi/gomega"
+)
+
+func TestSuite(t *testing.T) {
+	type tag struct{}
+	gomega.RegisterFailHandler(ginkgo.Fail)
+	ginkgo.RunSpecs(t, reflect.TypeOf(tag{}).PkgPath())
+}

internal/location/linenumber_test.go

@@ -0,0 +1,57 @@
+package location_test
+
+// This file contains definitions used within tests that check for specific line
+// numbers. To minimize test disruption edit this file as infrequently as
+// possible.
+//
+// New additions should always be made at the end so that the line numbers of
+// existing definitions do not change. The padding below can be removed as
+// imports statements added.
+
+import (
+	. "github.com/dogmatiq/testkit/internal/location"
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+	// import padding
+)
+
+func doNothing()             {}
+func doPanic()               { panic("<panic>") }
+func ofCallLayer1() Location { return OfCall() }
+func ofCallLayer2() Location { return ofCallLayer1() }
+
+type ofMethodT struct{}
+
+func (ofMethodT) Method() {}