test: add AccessTokenFetcher tests

src/Fetcher/AccessTokenFetcher.php

@@ -119,6 +119,10 @@ public function getProjectId(callable $_ = null) {
      * @return string The signature for the given string.
      */
     public function signBlob($stringToSign, $forceOpenssl = false) {
+        if (!$this->source->supportsCapability(Credentials::CAN_GENERATE_SIGNATURE)) {
+            throw new \BadMethodCallException(\get_class($this->source) . " does not support generating signatures");
+        }
+
         return $this->source->generateSignature($stringToSign)->getSignature();
     }
 

tests/Unit/Fetcher/AccessTokenFetcherTest.php

@@ -0,0 +1,150 @@
+<?php declare(strict_types=1);
+
+namespace ericnorris\GCPAuthContrib\Tests\Unit\Credentials;
+
+use PHPUnit\Framework\TestCase;
+
+use ericnorris\GCPAuthContrib\Contracts\Credentials;
+use ericnorris\GCPAuthContrib\Fetcher\AccessTokenFetcher;
+use ericnorris\GCPAuthContrib\Response\FetchAccessTokenResponse;
+
+
+final class AccessTokenFetcherTest extends TestCase {
+
+    private const EXAMPLE_SCOPES_01 = [
+        "https://www.googleapis.com/auth/cloud-platform",
+    ];
+
+    private const TOKEN_STRING = "token-string";
+    private const EXPIRES_AT   = 1234;
+
+
+    public function setUp(): void {
+        $this->mockCredentials = $this->createMock(Credentials::class);
+
+        $this->sut = new AccessTokenFetcher($this->mockCredentials, self::EXAMPLE_SCOPES_01);
+    }
+
+    public function testFetchesAuthToken(): void {
+        $this->assertNull($this->sut->getLastReceivedToken());
+
+        $accessTokenResponse = new FetchAccessTokenResponse(self::TOKEN_STRING, self::EXPIRES_AT, "", "Bearer");
+
+        $this->mockCredentials
+            ->expects($this->once())
+            ->method("fetchAccessToken")
+            ->with(self::EXAMPLE_SCOPES_01)
+            ->willReturn($accessTokenResponse);
+
+        $want = [
+            "access_token" => self::TOKEN_STRING,
+            "expires_at"   => self::EXPIRES_AT,
+        ];
+
+        $got = $this->sut->fetchAuthToken();
+
+        $this->assertEquals($want, $got);
+
+        $got = $this->sut->getLastReceivedToken();
+
+        $this->assertEquals($want, $got);
+    }
+
+    public function testGetsClientName(): void {
+        $this->mockCredentials
+            ->expects($this->once())
+            ->method("fetchServiceAccountEmail")
+            ->willReturn($want = "some-email");
+
+        $got = $this->sut->getClientName();
+
+        $this->assertSame($want, $got);
+    }
+
+    public function testGetsProjectID(): void {
+        $this->mockCredentials
+            ->expects($this->any())
+            ->method("supportsCapability")
+            ->will($this->returnCallback(function(string $capability) {
+                switch ($capability) {
+                    case Credentials::CAN_FETCH_PROJECT_ID:
+                        return true;
+
+                    default:
+                        return false;
+                }
+            }));
+
+        $this->mockCredentials
+            ->expects($this->once())
+            ->method("fetchProjectID")
+            ->willReturn($want = "some-project");
+
+        $got = $this->sut->getProjectId();
+
+        $this->assertSame($want, $got);
+    }
+
+    public function testReturnsNullForGetProjectID(): void {
+        $this->mockCredentials
+            ->expects($this->any())
+            ->method("supportsCapability")
+            ->will($this->returnCallback(function(string $capability) {
+                switch ($capability) {
+                    default:
+                        return false;
+                }
+            }));
+
+        $this->mockCredentials
+            ->expects($this->never())
+            ->method("fetchProjectID")
+            ->willReturn("shouldn't be called");
+
+        $got = $this->sut->getProjectId();
+
+        $this->assertNull($got);
+    }
+
+    public function testSignsBlob(): void {
+        $this->mockCredentials
+            ->expects($this->any())
+            ->method("supportsCapability")
+            ->will($this->returnCallback(function(string $capability) {
+                switch ($capability) {
+                    case Credentials::CAN_GENERATE_SIGNATURE:
+                        return true;
+
+                    default:
+                        return false;
+                }
+            }));
+
+        $this->mockCredentials
+            ->expects($this->once())
+            ->method("generateSignature");
+
+        $this->sut->signBlob("toSign");
+    }
+
+    public function testThrowsExceptionForSignBlob(): void {
+        $this->mockCredentials
+            ->expects($this->any())
+            ->method("supportsCapability")
+            ->will($this->returnCallback(function(string $capability) {
+                switch ($capability) {
+                    default:
+                        return false;
+                }
+            }));
+
+        $this->mockCredentials
+            ->expects($this->never())
+            ->method("generateSignature");
+
+        $this->expectException(\BadMethodCallException::class);
+
+        $this->sut->signBlob("toSign");
+    }
+
+}