lang: Add per-test config with count maximums

Some of our special tests can only be run once per `go test` invocation.
That is, using the test -count flag will cause a guaranteed failure
since we depend on a global being initialized only once as part of that
test.

This adds a per-test config option so that a user can specify to never
run a particular test more than once. This lets us continue to use the
-count flag with the test suite, without it causing some tests to fail.

lang/interpret_test.go

@@ -22,6 +22,7 @@ package lang
 import (
 	"bytes"
 	"context"
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -62,6 +63,24 @@ const (
 	runGraphviz = false // run graphviz in tests?
 )
 
+var (
+	testMutex   *sync.Mutex     // guards testCounter
+	testCounter map[string]uint // counts how many times each test ran
+)
+
+func init() {
+	testMutex = &sync.Mutex{}
+	testCounter = make(map[string]uint)
+}
+
+// ConfigProperties are some values that are used to specify how each test runs.
+type ConfigProperties struct {
+
+	// MaximumCount specifies how many times this test can run safely in a
+	// single iteration. If zero then this means infinite.
+	MaximumCount uint `json:"maximum-count"`
+}
+
 // TestAstFunc1 is a more advanced version which pulls code from physical dirs.
 func TestAstFunc1(t *testing.T) {
 	const magicError = "# err: "
@@ -169,6 +188,7 @@ func TestAstFunc1(t *testing.T) {
 
 			// copy files out into the test temp directory
 			var testOutput []byte
+			var testConfig []byte
 			found := false
 			for _, file := range archive.Files {
 				if file.Name == "OUTPUT" {
@@ -176,6 +196,10 @@ func TestAstFunc1(t *testing.T) {
 					found = true
 					continue
 				}
+				if file.Name == "CONFIG" {
+					testConfig = file.Data
+					continue
+				}
 
 				name := filepath.Join(tmpdir, file.Name)
 				dir := filepath.Dir(name)
@@ -189,6 +213,29 @@ func TestAstFunc1(t *testing.T) {
 				}
 			}
 
+			var c ConfigProperties // add pointer to get nil if empty
+			if len(testConfig) > 0 {
+				if err := json.Unmarshal(testConfig, &c); err != nil {
+					t.Errorf("err parsing txtar(%s) config: %+v", txtarFile, err)
+					return
+				}
+			}
+			if testing.Verbose() {
+				t.Logf("config: %+v", c)
+			}
+
+			testMutex.Lock()               // global
+			count := testCounter[t.Name()] // global
+			testCounter[t.Name()]++
+			testMutex.Unlock()
+
+			if c.MaximumCount != 0 && count >= c.MaximumCount {
+				if count == c.MaximumCount { // logf once
+					t.Logf("Skipping test after count: %d", count)
+				}
+				return
+			}
+
 			if !found { // skip missing tests
 				return
 			}
@@ -624,6 +671,7 @@ func TestAstFunc2(t *testing.T) {
 
 			// copy files out into the test temp directory
 			var testOutput []byte
+			var testConfig []byte
 			found := false
 			for _, file := range archive.Files {
 				if file.Name == "OUTPUT" {
@@ -631,6 +679,10 @@ func TestAstFunc2(t *testing.T) {
 					found = true
 					continue
 				}
+				if file.Name == "CONFIG" {
+					testConfig = file.Data
+					continue
+				}
 
 				name := filepath.Join(tmpdir, file.Name)
 				dir := filepath.Dir(name)
@@ -644,6 +696,29 @@ func TestAstFunc2(t *testing.T) {
 				}
 			}
 
+			var c ConfigProperties // add pointer to get nil if empty
+			if len(testConfig) > 0 {
+				if err := json.Unmarshal(testConfig, &c); err != nil {
+					t.Errorf("err parsing txtar(%s) config: %+v", txtarFile, err)
+					return
+				}
+			}
+			if testing.Verbose() {
+				t.Logf("config: %+v", c)
+			}
+
+			testMutex.Lock()               // global
+			count := testCounter[t.Name()] // global
+			testCounter[t.Name()]++
+			testMutex.Unlock()
+
+			if c.MaximumCount != 0 && count >= c.MaximumCount {
+				if count == c.MaximumCount { // logf once
+					t.Logf("Skipping test after count: %d", count)
+				}
+				return
+			}
+
 			if !found { // skip missing tests
 				return
 			}
@@ -1404,6 +1479,7 @@ func TestAstFunc3(t *testing.T) {
 
 			// copy files out into the test temp directory
 			var testOutput []byte
+			var testConfig []byte
 			found := false
 			for _, file := range archive.Files {
 				if file.Name == "OUTPUT" {
@@ -1411,6 +1487,10 @@ func TestAstFunc3(t *testing.T) {
 					found = true
 					continue
 				}
+				if file.Name == "CONFIG" {
+					testConfig = file.Data
+					continue
+				}
 
 				name := filepath.Join(tmpdir, file.Name)
 				dir := filepath.Dir(name)
@@ -1424,6 +1504,29 @@ func TestAstFunc3(t *testing.T) {
 				}
 			}
 
+			var c ConfigProperties // add pointer to get nil if empty
+			if len(testConfig) > 0 {
+				if err := json.Unmarshal(testConfig, &c); err != nil {
+					t.Errorf("err parsing txtar(%s) config: %+v", txtarFile, err)
+					return
+				}
+			}
+			if testing.Verbose() {
+				t.Logf("config: %+v", c)
+			}
+
+			testMutex.Lock()               // global
+			count := testCounter[t.Name()] // global
+			testCounter[t.Name()]++
+			testMutex.Unlock()
+
+			if c.MaximumCount != 0 && count >= c.MaximumCount {
+				if count == c.MaximumCount { // logf once
+					t.Logf("Skipping test after count: %d", count)
+				}
+				return
+			}
+
 			if !found { // skip missing tests
 				return
 			}