Don't depend on String8 cast to C string

Bug: 295394788
Test: m checkbuild
Change-Id: I5b86ae56250d409a23ab3f2bc72b725bcf6ab23e
diff --git a/libutils/String8_test.cpp b/libutils/String8_test.cpp
index 9c12cb1..e1fd13a 100644
--- a/libutils/String8_test.cpp
+++ b/libutils/String8_test.cpp
@@ -100,19 +100,19 @@
 TEST_F(String8Test, ValidUtf16Conversion) {
     char16_t tmp[] = u"abcdef";
     String8 valid = String8(String16(tmp));
-    EXPECT_STREQ(valid, "abcdef");
+    EXPECT_STREQ(valid.c_str(), "abcdef");
 }
 
 TEST_F(String8Test, append) {
     String8 s;
     EXPECT_EQ(OK, s.append("foo"));
-    EXPECT_STREQ("foo", s);
+    EXPECT_STREQ("foo", s.c_str());
     EXPECT_EQ(OK, s.append("bar"));
-    EXPECT_STREQ("foobar", s);
+    EXPECT_STREQ("foobar", s.c_str());
     EXPECT_EQ(OK, s.append("baz", 0));
-    EXPECT_STREQ("foobar", s);
+    EXPECT_STREQ("foobar", s.c_str());
     EXPECT_EQ(NO_MEMORY, s.append("baz", SIZE_MAX));
-    EXPECT_STREQ("foobar", s);
+    EXPECT_STREQ("foobar", s.c_str());
 }
 
 TEST_F(String8Test, removeAll) {
@@ -123,12 +123,12 @@
 
     // expect to return true and string content should remain unchanged
     EXPECT_TRUE(s.removeAll(""));
-    EXPECT_STREQ("Hello, world!", s);
+    EXPECT_STREQ("Hello, world!", s.c_str());
 
     // expect to return false
     EXPECT_FALSE(s.removeAll("x"));
-    EXPECT_STREQ("Hello, world!", s);
+    EXPECT_STREQ("Hello, world!", s.c_str());
 
     EXPECT_TRUE(s.removeAll("o"));
-    EXPECT_STREQ("Hell, wrld!", s);
+    EXPECT_STREQ("Hell, wrld!", s.c_str());
 }