Add check for invalid sources

Author: VMitov

cmd/casper/context.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net/url"
 	"os"
+	"strings"
 
 	"github.com/miracl/casper"
 	"github.com/miracl/casper/source"
@@ -46,6 +47,10 @@ func (c *context) withSources(sources []string) error {
 		}
 
 		if u.Scheme == "" {
+			if !strings.Contains(s, "=") {
+				return fmt.Errorf("invalid source: %v", s)
+			}
+
 			// default to config
 			u = &url.URL{
 				Scheme:   configScheme,

cmd/casper/main_test.go

@@ -51,13 +51,17 @@ func TestExample(t *testing.T) {
 		out  string // expected output
 		pwd  string // change the directory relative to working dir if set
 		copy bool   // copy the example folder in temporary dir if set
+		err  string // string representation of expected error
 	}{
 		{cmd: "casper fetch", out: outputFile + "\n", pwd: "../../example"},
 		{cmd: "casper diff -key somekey", out: "No changes for key somekey\n", pwd: "../../example"},
 
 		// without config file
 		{cmd: "casper build -t ../../example/template.yaml -s placeholder1=val1 -s placeholder2=val2", out: outputFile},
 
+		// with bad source
+		{cmd: "casper build -t ../../example/template.yaml -s placeholder1=val1 -s source.yaml", out: outputFile, err: "creating context failed: invalid source: source.yaml"},
+
 		// without sources
 		{cmd: "casper build -t ../../example/output.yaml", out: outputFile},
 		{cmd: "casper diff -t ../../example/output.yaml -storage file -file-path ../../example/output.yaml", out: noChanges},
@@ -112,6 +116,15 @@ func TestExample(t *testing.T) {
 				}
 			}()
 
+			if tc.err != "" {
+				app := newApp()
+				err := app.Run(strings.Split(tc.cmd, " "))
+				if err.Error() != tc.err {
+					t.Fatalf("\nunexpected error: %v\n\texpected: %v", err, tc.err)
+				}
+				return
+			}
+
 			if tc.pwd != "" {
 				os.Chdir(tc.pwd)
 			}