Add tests for logger pass

tests/various/logger_error.ys

@@ -0,0 +1,6 @@
+logger -werror "is implicitly declared." -expect error "is implicitly declared." 1
+read_verilog << EOF
+module top(...);
+	assign b = w;
+endmodule
+EOF

tests/various/logger_nowarning.ys

@@ -0,0 +1,6 @@
+logger -expect-no-warnings -nowarn "is implicitly declared."
+read_verilog << EOF
+module top(...);
+	assign b = w;
+endmodule
+EOF

tests/various/logger_warn.ys

@@ -0,0 +1,6 @@
+logger -warn "Successfully finished Verilog frontend." -expect warning "Successfully finished Verilog frontend." 1
+read_verilog << EOF
+module top(...);
+	assign b = w;
+endmodule
+EOF

tests/various/logger_warning.ys

@@ -0,0 +1,6 @@
+logger -expect warning "is implicitly declared." 2
+read_verilog << EOF
+module top(...);
+	assign b = w;
+endmodule
+EOF