Test: Add tests for command.go

conflict/command.go

@@ -8,12 +8,16 @@ import (
 	"syscall"
 )
 
-// RunCommand runs the given command with arguments and returns the output
+var execCommand = exec.Command
+var cwdEnvFlag = "GO_MOCK_PROCESS_DIRECTORY="
+
+// run runs the given command with arguments and returns the output
 // Refer to https://stackoverflow.com/questions/10385551/get-exit-code-go
 func run(name string, dir string, args ...string) (stdout string, stderr string, exitCode int) {
 	var outbuf, errbuf bytes.Buffer
-	cmd := exec.Command(name, args...)
+	cmd := execCommand(name, args...)
 	cmd.Dir = dir
+	cmd.Env = append(cmd.Env, cwdEnvFlag+dir)
 	cmd.Stdout = &outbuf
 	cmd.Stderr = &errbuf
 
@@ -59,8 +63,6 @@ func TopLevelPath(cwd string) (string, error) {
 
 	if len(stderr) != 0 {
 		return "", errors.New(stderr)
-	} else if len(stdout) == 0 {
-		return "", errors.New(stderr)
 	}
 
 	return string(strings.Split(stdout, "\n")[0]), nil

conflict/command_test.go

@@ -1,16 +1,94 @@
 package conflict
 
 import (
+	"fmt"
+	"os"
+	"os/exec"
 	"testing"
 )
 
+var mockValidDirectory = "/"
+var mockInvalidDirectory = "/hello/world"
+
 var commands = []struct {
 	command string
+	path    string
 	ok      bool
 }{
-	{"time", true},
-	{"foobar", false},
+	{"time", mockValidDirectory, true},
+	{"ls", mockValidDirectory, true},
+	{"less", mockInvalidDirectory, false},
+}
+
+func TestHelperProcess(t *testing.T) {
+	if os.Getenv("GO_WANT_HELPER_PROCESS") != "1" {
+		return
+	}
+
+	cwd := os.Getenv(cwdEnvFlag)
+
+	if cwd == mockInvalidDirectory {
+		fmt.Fprintf(os.Stderr, "Mock exec: Command tragically failed")
+		os.Exit(1)
+	} else {
+		fmt.Fprintf(os.Stdout, "Mock exec: Command succeeded")
+		os.Exit(0)
+	}
+}
+
+// Allows us to mock exec.Command, thanks to
+// https://npf.io/2015/06/testing-exec-command/
+func mockExecCommand(command string, args ...string) *exec.Cmd {
+	cs := []string{"-test.run=TestHelperProcess", "--", command}
+	cs = append(cs, args...)
+	cmd := exec.Command(os.Args[0], cs...)
+	cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1"}
+	return cmd
 }
 
 func TestRun(t *testing.T) {
+	execCommand = mockExecCommand
+	defer func() { execCommand = exec.Command }()
+
+	for _, test := range commands {
+		stdout, stderr, exitCode := run(test.command, test.path)
+
+		if test.ok && exitCode != 0 {
+			t.Errorf("run failed: got %s with exit code %d, expected no errors", stderr, exitCode)
+		} else if !(test.ok) && exitCode == 0 {
+			t.Errorf("run failed: got %s with exit code %d, expected errors", stdout, exitCode)
+		}
+	}
+}
+
+func TestTopLevelPath(t *testing.T) {
+	execCommand = mockExecCommand
+	defer func() { execCommand = exec.Command }()
+
+	tests := []string{mockValidDirectory, mockInvalidDirectory}
+	for _, test := range tests {
+		out, err := TopLevelPath(test)
+
+		if test == mockValidDirectory && err != nil {
+			t.Errorf("TopLevelPath failed: got %s, expected no errors", err.Error())
+		} else if test == mockInvalidDirectory && err == nil {
+			t.Errorf("TopLevelPath failed: got %s, expected errors", out)
+		}
+	}
+}
+
+func TestMarkerLocations(t *testing.T) {
+	execCommand = mockExecCommand
+	defer func() { execCommand = exec.Command }()
+
+	tests := []string{mockValidDirectory, mockInvalidDirectory}
+	for _, test := range tests {
+		out, err := MarkerLocations(test)
+
+		if test == mockValidDirectory && err != nil {
+			t.Errorf("TopLevelPath failed: got %s, expected no errors", err.Error())
+		} else if test == mockInvalidDirectory && err == nil {
+			t.Errorf("TopLevelPath failed: got %s, expected errors", out)
+		}
+	}
 }