Return package-specific error messagesformat-errors-and-use-error-values

Instead of passing errors through to clients, wrap them with a
"browserenv" error message to add context.

Add new error types that can be matched against.

1 files changed, 76 insertions, 0 deletions

diff --git a/error.go b/error.go
new file mode 100644
index 0000000..d90d1b8
--- /dev/null
+++ b/error.go
@@ -0,0 +1,76 @@
+package browserenv
+
+import "fmt"
+
+const errorPrefix = "browserenv: "
+
+// CopyError represents a failure to copy data.
+type CopyError struct {
+	err error
+}
+
+func (e *CopyError) Error() string {
+	return fmt.Sprintf(errorPrefix+"can't copy from reader: %v", e.err)
+}
+
+func (e *CopyError) Unwrap() error { return e.err }
+
+// ExecError results from executing an external command.
+type ExecError struct {
+	command string
+	err     error
+}
+
+func (e *ExecError) Error() string {
+	return fmt.Sprintf(
+		errorPrefix+"failed to run BROWSER command %q: %v",
+		e.command,
+		e.err,
+	)
+}
+
+func (e *ExecError) Unwrap() error { return e.err }
+
+// ExecZeroError results from executing an external command that produces an
+// error with an exit code of 0.
+type ExecZeroError struct {
+	command string
+	err     error
+}
+
+func (e *ExecZeroError) Error() string {
+	return fmt.Sprintf(
+		errorPrefix+"error running command %q: %v",
+		e.command,
+		e.err,
+	)
+}
+
+func (e *ExecZeroError) Unwrap() error { return e.err }
+
+// PathResolutionError means the given path couldn't be resolved.
+type PathResolutionError struct {
+	path string
+	err  error
+}
+
+func (e *PathResolutionError) Error() string {
+	return fmt.Sprintf(
+		errorPrefix+"can't resolve path for %q: %v",
+		e.path,
+		e.err,
+	)
+}
+
+func (e *PathResolutionError) Unwrap() error { return e.err }
+
+// TempFileError corresponds to an error while creating a temporary file.
+type TempFileError struct {
+	err error
+}
+
+func (e *TempFileError) Error() string {
+	return fmt.Sprintf(errorPrefix+"can't create temporary file: %v", e.err)
+}
+
+func (e *TempFileError) Unwrap() error { return e.err }