feat: improve handling of repeated parallel test setup (#60)

Signed-off-by: tkrop <[email protected]>

Makefile

@@ -19,7 +19,9 @@ endif
 # request targets, while the single target can be used to define the
 # precondition of custom target.
 .PHONY: $(TARGETS) $(addprefix target/,$(TARGETS))
-$(TARGETS):; $(GOBIN)/go-make $(MAKEFLAGS) $(MAKECMDGOALS);
+$(eval $(lastwords $(MAKECMDGOALS)):;@:)
+$(firstword $(MAKECMDGOALS)):
+	$(GOBIN)/go-make $(MAKEFLAGS) $(MAKECMDGOALS);
 $(addprefix target/,$(TARGETS)): target/%:
 	$(GOBIN)/go-make $(MAKEFLAGS) $*;
 

internal/mock/common_test.go

@@ -200,6 +200,11 @@ var (
 		Params:   []*Param{},
 		Results:  []*Param{{Type: "string"}},
 		Variadic: false,
+	}, {
+		Name:     "Parallel",
+		Params:   []*Param{},
+		Results:  []*Param{},
+		Variadic: false,
 	}, {
 		Name:     "TempDir",
 		Params:   []*Param{},

test/caller_test.go

@@ -94,7 +94,7 @@ var (
 	}()
 	// CallerTestErrorf provides the file with the line number of the `Errorf`
 	// call in testing.
-	CallerTestErrorf = path.Join(SourceDir, "testing.go:180")
+	CallerTestErrorf = path.Join(SourceDir, "testing.go:211")
 	// CallerGomockErrorf provides the file with the line number of the
 	// `Errorf` call in gomock.
 	CallerGomockErrorf = path.Join(SourceDir, "gomock.go:61")

test/testing.go

@@ -40,6 +40,18 @@ const (
 	Parallel = true
 )
 
+// ensureParallel ensures that the test runs test parameter sets in parallel.
+func ensureParallel(t *testing.T) {
+	t.Helper()
+	defer func() {
+		if v := recover(); v != nil &&
+			v != "testing: t.Parallel called multiple times" {
+			panic(v)
+		}
+	}()
+	t.Parallel()
+}
+
 // TODO: consider following convenience methods:
 //
 // // Result is a convenience method that returns the first argument ans swollows
@@ -87,12 +99,31 @@ type Reporter interface {
 // Test is a minimal interface for abstracting test methods that are needed to
 // setup an isolated test environment for GoMock and Testify.
 type Test interface {
+	// Helper declares a test helper function. The method delegates the request
+	// to the parent test context.
 	Helper()
+	// Name provides the test name. The method delegates the request to the
+	// parent test context.
 	Name() string
+	// TempDir creates a new temporary directory for the test. The method
+	// delegates the request to the parent test context.
 	TempDir() string
+	// Errorf handles a failure messages when a test is supposed to continue.
+	// The method either delegates the request to the parent test context or
+	// to the test reporter.
 	Errorf(format string, args ...any)
+	// Fatalf handles a fatal failure messge that immediate aborts of the test
+	// execution. The method either delegates the request to the parent test
+	// context or to the test reporter.
 	Fatalf(format string, args ...any)
+	// FailNow handles fatal failure notifications without log output that
+	// aborts test execution immediately. The method either delegates the
+	// request to the parent test context or to the test reporter.
 	FailNow()
+	// Parallel declares that the test is to be run in parallel with (and only
+	// with) other parallel tests. The method delegates the request to the
+	// parent test context and silently recovers when setting up twice.
+	Parallel()
 }
 
 // Cleanuper defines an interface to add a custom mehtod that is called after
@@ -127,7 +158,7 @@ func NewTester(t Test, expect Expect) *Tester {
 // Parallel delegates request to `testing.T.Parallel()`.
 func (t *Tester) Parallel() {
 	if t, ok := t.t.(*testing.T); ok {
-		t.Parallel()
+		ensureParallel(t)
 	}
 }
 
@@ -391,15 +422,21 @@ func (r *runner[P]) RunSeq(call func(t Test, param P)) Runner[P] {
 	return r.run(call, false)
 }
 
+// parallel ensures that the test runner runs the test parameter sets in
+// parallel.
+func (r *runner[P]) parallel(parallel bool) {
+	if parallel {
+		ensureParallel(r.t)
+	}
+}
+
 // Run runs the test parameter sets either parallel or in sequence.
 func (r *runner[P]) run(
 	call func(t Test, param P), parallel bool,
 ) Runner[P] {
 	switch params := r.params.(type) {
 	case map[string]P:
-		if parallel {
-			r.t.Parallel()
-		}
+		r.parallel(parallel)
 		r.wg.Add(len(params))
 
 		for name, param := range params {
@@ -408,9 +445,7 @@ func (r *runner[P]) run(
 		}
 
 	case []P:
-		if parallel {
-			r.t.Parallel()
-		}
+		r.parallel(parallel)
 		r.wg.Add(len(params))
 
 		for index, param := range params {

test/testing_test.go

@@ -280,3 +280,22 @@ func TestTypePanic(t *testing.T) {
 	test.New[TestParam](t, ParamParam{expect: false}).
 		Run(func(t test.Test, param TestParam) {})
 }
+
+func TestParallel(t *testing.T) {
+	t.Parallel()
+	test.New[ParamParam](t, []ParamParam{{expect: false}}).
+		Run(func(t test.Test, param ParamParam) {
+			t.Parallel()
+		})
+}
+
+func TestParallelDenied(t *testing.T) {
+	t.Setenv("TESTING", "true")
+	defer func() {
+		assert.Equal(t, "testing: t.Parallel called after t.Setenv;"+
+			" cannot set environment variables in parallel tests", recover())
+	}()
+
+	test.New[ParamParam](t, []ParamParam{{expect: false}}).
+		Run(func(t test.Test, param ParamParam) {})
+}