adding an extra auth test to check computeSharedKey

```
=== RUN   TestComputeSharedKey
--- PASS: TestComputeSharedKey (0.00s)
    authorizer_shared_key_lite_test.go:87: [DEBUG] Test "No Path"
    authorizer_shared_key_lite_test.go:87: [DEBUG] Test "With Path"
PASS
```

azurerm/internal/authorizers/authorizer_shared_key_lite_test.go

@@ -1,6 +1,7 @@
 package authorizers
 
 import (
+	"net/http"
 	"testing"
 )
 
@@ -34,3 +35,69 @@ func TestBuildCanonicalizedStringForSharedKeyLite(t *testing.T) {
 		}
 	}
 }
+
+func TestComputeSharedKey(t *testing.T) {
+	testData := []struct {
+		name        string
+		accountName string
+		method      string
+		url         string
+		headers     map[string]string
+		expected    string
+	}{
+		{
+			name:        "No Path",
+			accountName: "unlikely23exst2acct23wi",
+			method:      "GET",
+			url:         "https://unlikely23exst2acct23wi.queue.core.windows.net?comp=properties&restype=service",
+			headers: map[string]string{
+				"Content-Type": "application/xml; charset=utf-8",
+				"X-Ms-Date":    "Wed, 21 Aug 2019 11:00:25 GMT",
+				"X-Ms-Version": "2018-11-09",
+			},
+			expected: `GET
+
+application/xml; charset=utf-8
+
+x-ms-date:Wed, 21 Aug 2019 11:00:25 GMT
+x-ms-version:2018-11-09
+/unlikely23exst2acct23wi?comp=properties`,
+		},
+		{
+			name:        "With Path",
+			accountName: "unlikely23exst2accti1t0",
+			method:      "GET",
+			url:         "https://unlikely23exst2accti1t0.queue.core.windows.net/?comp=properties&restype=service",
+			headers: map[string]string{
+				"Content-Type": "application/xml; charset=utf-8",
+				"X-Ms-Date":    "Wed, 21 Aug 2019 11:53:48 GMT",
+				"X-Ms-Version": "2018-11-09",
+			},
+			expected: `GET
+
+application/xml; charset=utf-8
+
+x-ms-date:Wed, 21 Aug 2019 11:53:48 GMT
+x-ms-version:2018-11-09
+/unlikely23exst2accti1t0/?comp=properties`,
+		},
+	}
+
+	for _, v := range testData {
+		t.Logf("[DEBUG] Test %q", v.name)
+
+		headers := http.Header{}
+		for hn, hv := range v.headers {
+			headers.Add(hn, hv)
+		}
+
+		actual, err := computeSharedKeyLite(v.method, v.url, v.accountName, headers)
+		if err != nil {
+			t.Fatalf("Error computing shared key: %s", err)
+		}
+
+		if *actual != v.expected {
+			t.Fatalf("Expected %q but got %q", v.expected, *actual)
+		}
+	}
+}