Initial work

command/inspect_test.go

@@ -94,6 +94,26 @@ Use it at will.
         manifest
         shell-local
 
+`},
+		{[]string{"inspect", "-var=fruit=peach", filepath.Join(testFixture("var-arg"), "fruit_builder.json")}, nil, `Packer Inspect: JSON mode
+Required variables:
+
+  fruit
+
+Optional variables and their defaults:
+
+
+Builders:
+
+  null
+
+Provisioners:
+
+  <No provisioners>
+
+Note: If your build names contain user variables or template
+functions such as 'timestamp', these are processed at build time,
+and therefore only show in their raw form here.
 `},
 	}
 
@@ -107,7 +127,7 @@ Use it at will.
 			}
 			actual := string(bs)
 			if diff := cmp.Diff(tc.expected, actual); diff != "" {
-				t.Fatalf("unexpected ouput %s", diff)
+				t.Fatalf("unexpected output %s", diff)
 			}
 		})
 	}

command/test-fixtures/var-arg/fruit_builder.json

@@ -1,6 +1,6 @@
 {
     "variables": {
-        "fruit": ""
+        "fruit": null
     },
     "builders": [
         {